Engine over-cooling
Discussion
BeastMaster said:
Mine is exactly the same.
During the very cold months I insert a blanking panel in the middle of the rad, which covers a portion of each fan to cut down the cold air blast. This allows the temp to be similar to summer months and increases the heater output. In traffic the temp is the same as summer, less air is sucked through the rad but it is colder.
Very high performance cars have this type of thing auto operated, mainly to decrease drag, did think of making a mechanical operator, or even an electrical system running off water temp, but sticking a blanking piece in seemed much more TVR.
Andy.
Thanks Andy, glad to hear it's not just me. I actually trial fitted a piece of thick cardboard in the centre, thinking that it would allow each fan to pull through as you said. It pinged into the slot between the body and the bottom of the rad and then snapped into place behind the air filter. Then I thought about the mess it would make if I drove in the rain ! So now, I'm thinking thin perspex or something similar.During the very cold months I insert a blanking panel in the middle of the rad, which covers a portion of each fan to cut down the cold air blast. This allows the temp to be similar to summer months and increases the heater output. In traffic the temp is the same as summer, less air is sucked through the rad but it is colder.
Very high performance cars have this type of thing auto operated, mainly to decrease drag, did think of making a mechanical operator, or even an electrical system running off water temp, but sticking a blanking piece in seemed much more TVR.
Andy.
taylormj4 said:
Bobfather, I understand what you're saying and agree that the gauge could be sited poorly and exhibit those conditions but my point is this: if the gauge is reading incorrectly low and the coolant is actually at a much higher temperature, why does the temperature of the air output from the heater go cooler when the gauge drops ? Surely if the coolant was actually hot (as you suggest), the heater output would remain high. My experience is that the heater output temperature (which is linked to coolant temperature) matches the temperature gauge. That suggests the gauge is reading correctly.
Very simple answer. The heater matrix on full heat increases the temperature of air flowing through it by a set amount, say it adds 20degC.
If the outside air is 22degC, the heated air will be 22 + 20 so the hot air into the car will be 42degC.
If the outside air is 5degC, the heated air will be 5 + 20 so the hot air into the car will be 25degC.
I was reading a thread in a US Jag forum the other week and it was discussing what a thermostat actually does.
It got quite heated as the main contributor was suggesting that the stat is only there to heat up the coolant on start up.
Once at operating temperature it was always open. The design of the cooling system kept the engine temp within operating parameters. It was quite interesting reading the arguments . I would suggest it could be true depending on the ambient air temp where the car is being driven.
Our cars generate enough heat for this to be true over here.
I have always had a 74 degree stat . 10 years now and I always have a hot heater . Gauge always low this time of year.
It got quite heated as the main contributor was suggesting that the stat is only there to heat up the coolant on start up.
Once at operating temperature it was always open. The design of the cooling system kept the engine temp within operating parameters. It was quite interesting reading the arguments . I would suggest it could be true depending on the ambient air temp where the car is being driven.
Our cars generate enough heat for this to be true over here.
I have always had a 74 degree stat . 10 years now and I always have a hot heater . Gauge always low this time of year.
Just to add to this, I run an 88 degree thermostat which contrary to the scepticism of many TVR owners I've proven works perfectly with no overheating issues whatsoever, even in very hot summer traffic.
I run a Canems engine management system which shows the true coolant temperature and is used by the ECU itself to manage fuelling and other outputs such as radiator fan operation ect, the temperature is taken from the original 14CUX coolant temp sensor.
What I see on my laptop is the same as the ECU sees and is an extremely accurate reading, with the 88 degree thermostat the coolant never exceeds an absolute maximum temperature of 92 degrees when idling in traffic on the hottest summer day but in all other climates the coolant temperature is very effectively managed at 88 degrees when the engine is idling.
When driving coolant temperature will drop below the 88 degree figure, the amount varies ]on ambient temperature. In summer I typically see between 83-85 degrees at cruising speeds, in the winter this can drop to 80 degrees. So the truth is in my case running an 88 degree thermostat all I see is 3-5 degree drop in coolant temperature between summer and winter.
This isn't really as much of a drop as you might expect, while my 88 degree thermostat is certainly helping here it's not the full story. We have all experienced the drop in heater performance during the winter, but is it really all a drop in heater performance or is there something else at play? What's often overlooked is the Chimaera is quite a leaky old thing, I'm not talking water (although water ingress can be an issue too), I'm referring to air ingress from the outside into the cabin at speed.
This air blast enters the car and during the winter considerably cools the temperature of the cabin, the heater is producing more of less the same heat output but it has to fight the effects of a much cooler cabin. A Chimaera heater is actually verrry efficient but in my experience the air blast vs heater fight only ends in what I'd call "acceptable" cabin temperatures at speed in very cold weather.
If you want to reduce this chilly wind blast and up your cabin temps firstly its worth fitting an 88 degree thermostat, then blank off the lower third of your radiator with a sheet of corrugated plastic, finally block off the two 'Ned The Dog Bite' air scoops immediately below the indicators.
These two air scoops are where 70% of the chilly air blast entering the cabin originates from, air enters these openings and travels through the void formed between the front wings and the inner wheel arches, its a ram air effect and is there by design to give you fresh air circulation in the cabin. It works well and you wouldn't want to be without it in most situations, but on really cold days it really only serves to lower cabin temps below what you might like even though the heater is very effective.
Block these two ram air ventilation openings in the winter and you'll find your cabin temps rise considerably, the car will remain adequately ventilated as the car still leaks in air from other areas but it will make things more comfortable when driving the car in the winter.
Hope this helps?
Dave.
I run a Canems engine management system which shows the true coolant temperature and is used by the ECU itself to manage fuelling and other outputs such as radiator fan operation ect, the temperature is taken from the original 14CUX coolant temp sensor.
What I see on my laptop is the same as the ECU sees and is an extremely accurate reading, with the 88 degree thermostat the coolant never exceeds an absolute maximum temperature of 92 degrees when idling in traffic on the hottest summer day but in all other climates the coolant temperature is very effectively managed at 88 degrees when the engine is idling.
When driving coolant temperature will drop below the 88 degree figure, the amount varies ]on ambient temperature. In summer I typically see between 83-85 degrees at cruising speeds, in the winter this can drop to 80 degrees. So the truth is in my case running an 88 degree thermostat all I see is 3-5 degree drop in coolant temperature between summer and winter.
This isn't really as much of a drop as you might expect, while my 88 degree thermostat is certainly helping here it's not the full story. We have all experienced the drop in heater performance during the winter, but is it really all a drop in heater performance or is there something else at play? What's often overlooked is the Chimaera is quite a leaky old thing, I'm not talking water (although water ingress can be an issue too), I'm referring to air ingress from the outside into the cabin at speed.
This air blast enters the car and during the winter considerably cools the temperature of the cabin, the heater is producing more of less the same heat output but it has to fight the effects of a much cooler cabin. A Chimaera heater is actually verrry efficient but in my experience the air blast vs heater fight only ends in what I'd call "acceptable" cabin temperatures at speed in very cold weather.
If you want to reduce this chilly wind blast and up your cabin temps firstly its worth fitting an 88 degree thermostat, then blank off the lower third of your radiator with a sheet of corrugated plastic, finally block off the two 'Ned The Dog Bite' air scoops immediately below the indicators.
These two air scoops are where 70% of the chilly air blast entering the cabin originates from, air enters these openings and travels through the void formed between the front wings and the inner wheel arches, its a ram air effect and is there by design to give you fresh air circulation in the cabin. It works well and you wouldn't want to be without it in most situations, but on really cold days it really only serves to lower cabin temps below what you might like even though the heater is very effective.
Block these two ram air ventilation openings in the winter and you'll find your cabin temps rise considerably, the car will remain adequately ventilated as the car still leaks in air from other areas but it will make things more comfortable when driving the car in the winter.
Hope this helps?
Dave.
taylormj4 said:
Thanks Andy, glad to hear it's not just me. I actually trial fitted a piece of thick cardboard in the centre, thinking that it would allow each fan to pull through as you said. It pinged into the slot between the body and the bottom of the rad and then snapped into place behind the air filter. Then I thought about the mess it would make if I drove in the rain ! So now, I'm thinking thin perspex or something similar.
just as a sense check - I assume you don't have an oil cooler - if you do you need to cover it up in the winter as the oil gets over cooled - my oil was at 40 degrees which is not good!. I actually use the piece of card over the oil cooler in front of the rad all winter and it doesnt disintegrate even in rain. a nice shiny cornflakes packet works really well and looks great. (-:My final point on this is the Chimaera with a 74 degree thermostat will run at more or less the same temperature as my Chimaera with it's 88 degree thermostat. The difference will be how long it takes for each car to reach operating temperature, this is because running temperature is governed by the cooling system (rad, water pump, coolant capacity) not the thermostat.
You could run a Chimaera with no thermostat at all and it would still eventually reach the typical 80 degree/ish running temperature when the car is on the move and settle there, it would just take ages to get to 80 degrees. Also keep in mind the TVR gauge is not the most accurate instrument in the world and where TVR put the sender is plane daft, the two combined mean what you see on the gauge is more of an indication of an approximate temp than a genuinely accurate reading.
My advice to anyone feeling the chill is to put some corrugated plastic over the cooler lower third of their rad and block those holes under the indicators to reduce the wind blast, holes that channel super cooled air down the wings and is forced into the cabin. People need to understand a thermostat is just a device to aid faster warm up, fitting a lower value thermostat does not reduce the running temperature of your engine and it most definitely will not fix a cooling issue, a lower value thermostat just opens sooner so it'll take longer for the coolant to reach its fixed operating temperature.
There is no difference between a fully open 74 degree thermostat and a fully open 88 degree thermostat or even no thermostat at all, its all the same, what really counts is the design of the cooling system and how well it's been maintained. Oh and the temperature of the air that passes through you rad will make difference too, that's why adding some restriction to this air with a sheet of cardboard or better still corrugated plastic can really help a lot.
But it's the cold air blasting its way inside the car that's the real enemy of a nice cosy cabin during these winter months.
You could run a Chimaera with no thermostat at all and it would still eventually reach the typical 80 degree/ish running temperature when the car is on the move and settle there, it would just take ages to get to 80 degrees. Also keep in mind the TVR gauge is not the most accurate instrument in the world and where TVR put the sender is plane daft, the two combined mean what you see on the gauge is more of an indication of an approximate temp than a genuinely accurate reading.
My advice to anyone feeling the chill is to put some corrugated plastic over the cooler lower third of their rad and block those holes under the indicators to reduce the wind blast, holes that channel super cooled air down the wings and is forced into the cabin. People need to understand a thermostat is just a device to aid faster warm up, fitting a lower value thermostat does not reduce the running temperature of your engine and it most definitely will not fix a cooling issue, a lower value thermostat just opens sooner so it'll take longer for the coolant to reach its fixed operating temperature.
There is no difference between a fully open 74 degree thermostat and a fully open 88 degree thermostat or even no thermostat at all, its all the same, what really counts is the design of the cooling system and how well it's been maintained. Oh and the temperature of the air that passes through you rad will make difference too, that's why adding some restriction to this air with a sheet of cardboard or better still corrugated plastic can really help a lot.
But it's the cold air blasting its way inside the car that's the real enemy of a nice cosy cabin during these winter months.
ChimpOnGas said:
My final point on this is the Chimaera with a 74 degree thermostat will run at more or less the same temperature as my Chimaera with it's 88 degree thermostat. The difference will be how long it takes for each car to reach operating temperature, this is because running temperature is governed by the cooling system (rad, water pump, coolant capacity) not the thermostat.
You could run a Chimaera with no thermostat at all and it would still eventually reach the typical 80 degree/ish running temperature when the car is on the move and settle there, it would just take ages to get to 80 degrees. Also keep in mind the TVR gauge is not the most accurate instrument in the world and where TVR put the sender is plane daft, the two combined mean what you see on the gauge is more of an indication of an approximate temp than a genuinely accurate reading.
My advice to anyone feeling the chill is to put some corrugated plastic over the cooler lower third of their rad and block those holes under the indicators to reduce the wind blast, holes that channel super cooled air down the wings and is forced into the cabin. People need to understand a thermostat is just a device to aid faster warm up, fitting a lower value thermostat does not reduce the running temperature of your engine and it most definitely will not fix a cooling issue, a lower value thermostat just opens sooner so it'll take longer for the coolant to reach its fixed operating temperature.
There is no difference between a fully open 74 degree thermostat and a fully open 88 degree thermostat or even no thermostat at all, its all the same, what really counts is the design of the cooling system and how well it's been maintained. Oh and the temperature of the air that passes through you rad will make difference too, that's why adding some restriction to this air with a sheet of cardboard or better still corrugated plastic can really help a lot.
Agree with that Chimp on gas, the choice of stat was not my request but fitted by a reputable specialist whilst the cooling system was being overhauled, I'd have done it myself but I didn't have the time.You could run a Chimaera with no thermostat at all and it would still eventually reach the typical 80 degree/ish running temperature when the car is on the move and settle there, it would just take ages to get to 80 degrees. Also keep in mind the TVR gauge is not the most accurate instrument in the world and where TVR put the sender is plane daft, the two combined mean what you see on the gauge is more of an indication of an approximate temp than a genuinely accurate reading.
My advice to anyone feeling the chill is to put some corrugated plastic over the cooler lower third of their rad and block those holes under the indicators to reduce the wind blast, holes that channel super cooled air down the wings and is forced into the cabin. People need to understand a thermostat is just a device to aid faster warm up, fitting a lower value thermostat does not reduce the running temperature of your engine and it most definitely will not fix a cooling issue, a lower value thermostat just opens sooner so it'll take longer for the coolant to reach its fixed operating temperature.
There is no difference between a fully open 74 degree thermostat and a fully open 88 degree thermostat or even no thermostat at all, its all the same, what really counts is the design of the cooling system and how well it's been maintained. Oh and the temperature of the air that passes through you rad will make difference too, that's why adding some restriction to this air with a sheet of cardboard or better still corrugated plastic can really help a lot.
I'm fairly well versed in stats being in P and H for 26 years and the only advantage I can see is the earlier dispersal of heat that may help if your car has a tendency to overheat quickly in traffic...that's assuming you get out of it fairly quickly! Once the TVR is fully warmed and up around 90 degrees it's going to make little to no difference whether your stat is 74/75/82 or 88. Only when you are back on a fast run and temperatures drop will it stay open a longer or shorter duration as the coolant temp drops dependant on the stat rating.
All in the eye of the beholder.
The truth is you should always run the hottest thermostat you can prove causes no issues in the Summer and one of a value that exactly matches the highest natural operating temperature the cooling system is designed to reach at idle on a hot day with the rad fans running.
And here's why!
Taking the thermostat out of the equation for a moment and after much testing and monitoring of true coolant temps displayed via my Canems software I can confidently say my Chimaera (which in this respect is no different from any other) has a mean running temperature controlled by the overall design and capacity of the cooling system of 83 degrees.
This is 83 degrees at a minimum sustained road speed of 15mph and above so with the rad fans off, indeed if you never had to slow below 15mph you wouldn't even need rad fans as the coolant system would just get on with it's job of maintaining the 83 degrees perfectly well without. Idle conditions where there is no natural air flow through the rad is of course a very different story, under these conditions the rad fans are there to simulate that 15mph of air flow when road speed is below 15mph.
Now with that clear we can now return to the subject of thermostats, the first thing we need to understand is the true function and purpose of the thermostat, lets look at what a thermostat is & isn't to debunk the myths:
WHAT A THERMOSTAT ISN'T
1. 83 degrees
2. Reaching 83 degrees as quickly as possible
Irrespective of summer or winter driving anything you can do to get to the magic 83 degrees as quickly as possible is a very good thing because the engine will come off it's cold start fuelling map faster which saves fuel, reduces emissions and because you'll be into closed loop sooner the engine will run smoother sooner. Getting to the magic 83 degrees sooner also means the cabin will warm faster so in these chilly conditions it will be a much more comfortable place to be.
There are only benefits to faster warm up, modern cars go one step further, rather than just using a traditional thermostat the highly inefficient mechanical water pump that pumps away irrespective of coolant temperature is replaced with a thermostatically controlled electric water pump that actually does little or no pumping during the warm up phase, this significantly reduces warm up time so offers big benefits as already described.
Back to the Chimaera with is old school mechanical water pump and thermostat, now we know the objective is to reach the magic 83 degrees as quickly as possible and the only purpose of the thermostat is to help in achieving this objective we should clearly choose a thermostat value that helps us get to the 83 degrees as quickly as possible without restricting the ability for the overall design and capacity of the cooling system to maintain the natural mean running temperature of 83 degrees its been carefully designed to achieve.
With the function and purpose of the thermostat now properly understood it stands to reason the value of your chosen thermostat should at the very least match the magic 83 degrees and why anyone would fit a thermostat of a lower value than 83 degrees is absolutely beyond me
Fitting a thermostat that is fully open below the engine's natural mean running temperature of 83 degrees is just daft. Lets be 100% clear here, fitting a thermostat of a lower value than 83 degrees offers absolutely no benefits whatsoever, all it will do is waste fuel and ensure you and your engine are kept colder for longer as it slowly works its way to reach the 83 degrees, which eventually it has to... because 83 degrees is what the coolant system is designed to deliver.
Taking all this a step further I have conclusively proved a thermostat that is fully open at 88 degrees works best, it clearly allows faster engine warm up delivering all the benefits associated with that, it also has no impact on the upper coolant temps because all Chimaeras tend to sit around 88 degrees on the hottest summer day idling in traffic, the cooling system helped by the rad fans makes sure of that and with my thermostat fully open at 88 degrees it's actually doing nothing to make the coolant temp go any higher, how could it?
Also keep in mind what's as equally important to the fully open 88 degree figure is the temperature my 88 degree thermostat starts to open, this 'start to open' figure is higher than the lower value thermostats but is still way below the fully open figure, my 88 degree thermostat is also 98% fully open by around the magic 83 degrees figure. Thermostats don't snap open and close instantly, the process is controlled and gradual, if you actually study the 'start to open' figure of the lower value thermostats you'll soon see why they are such a bad idea.
For a Chimaera, as an absolute bare minimum you should always use a thermostat that's fully open at 83 degrees, the use of a thermostat of a lower value than the natural running temperature of the engine's coolant system is as I've proved and carefully explained above... completely pointless!. The truth is for maximum engine efficiency the target fully open temp rating of a thermostat should exactly match the highest natural operating temperature the cooling system is designed to reach at idle on a hot day with the rad fans running.
And in the case of a Chimaera that figure is 88 degrees...
Thems the facts boys
And here's why!
Taking the thermostat out of the equation for a moment and after much testing and monitoring of true coolant temps displayed via my Canems software I can confidently say my Chimaera (which in this respect is no different from any other) has a mean running temperature controlled by the overall design and capacity of the cooling system of 83 degrees.
This is 83 degrees at a minimum sustained road speed of 15mph and above so with the rad fans off, indeed if you never had to slow below 15mph you wouldn't even need rad fans as the coolant system would just get on with it's job of maintaining the 83 degrees perfectly well without. Idle conditions where there is no natural air flow through the rad is of course a very different story, under these conditions the rad fans are there to simulate that 15mph of air flow when road speed is below 15mph.
Now with that clear we can now return to the subject of thermostats, the first thing we need to understand is the true function and purpose of the thermostat, lets look at what a thermostat is & isn't to debunk the myths:
WHAT A THERMOSTAT ISN'T
- A solution for an engine that overheats..
- A method of reducing the mean running coolant temperature which is actually controlled by the overall design and capacity of the cooling system..
- A device to help the engine coolant reach it's mean running temperature controlled by the overall design and capacity of the cooling system which in the case of the Chimaera is 83 degrees, and to reach this magic 83 degrees as quickly as possible..
1. 83 degrees
2. Reaching 83 degrees as quickly as possible
Irrespective of summer or winter driving anything you can do to get to the magic 83 degrees as quickly as possible is a very good thing because the engine will come off it's cold start fuelling map faster which saves fuel, reduces emissions and because you'll be into closed loop sooner the engine will run smoother sooner. Getting to the magic 83 degrees sooner also means the cabin will warm faster so in these chilly conditions it will be a much more comfortable place to be.
There are only benefits to faster warm up, modern cars go one step further, rather than just using a traditional thermostat the highly inefficient mechanical water pump that pumps away irrespective of coolant temperature is replaced with a thermostatically controlled electric water pump that actually does little or no pumping during the warm up phase, this significantly reduces warm up time so offers big benefits as already described.
Back to the Chimaera with is old school mechanical water pump and thermostat, now we know the objective is to reach the magic 83 degrees as quickly as possible and the only purpose of the thermostat is to help in achieving this objective we should clearly choose a thermostat value that helps us get to the 83 degrees as quickly as possible without restricting the ability for the overall design and capacity of the cooling system to maintain the natural mean running temperature of 83 degrees its been carefully designed to achieve.
With the function and purpose of the thermostat now properly understood it stands to reason the value of your chosen thermostat should at the very least match the magic 83 degrees and why anyone would fit a thermostat of a lower value than 83 degrees is absolutely beyond me
Fitting a thermostat that is fully open below the engine's natural mean running temperature of 83 degrees is just daft. Lets be 100% clear here, fitting a thermostat of a lower value than 83 degrees offers absolutely no benefits whatsoever, all it will do is waste fuel and ensure you and your engine are kept colder for longer as it slowly works its way to reach the 83 degrees, which eventually it has to... because 83 degrees is what the coolant system is designed to deliver.
Taking all this a step further I have conclusively proved a thermostat that is fully open at 88 degrees works best, it clearly allows faster engine warm up delivering all the benefits associated with that, it also has no impact on the upper coolant temps because all Chimaeras tend to sit around 88 degrees on the hottest summer day idling in traffic, the cooling system helped by the rad fans makes sure of that and with my thermostat fully open at 88 degrees it's actually doing nothing to make the coolant temp go any higher, how could it?
Also keep in mind what's as equally important to the fully open 88 degree figure is the temperature my 88 degree thermostat starts to open, this 'start to open' figure is higher than the lower value thermostats but is still way below the fully open figure, my 88 degree thermostat is also 98% fully open by around the magic 83 degrees figure. Thermostats don't snap open and close instantly, the process is controlled and gradual, if you actually study the 'start to open' figure of the lower value thermostats you'll soon see why they are such a bad idea.
For a Chimaera, as an absolute bare minimum you should always use a thermostat that's fully open at 83 degrees, the use of a thermostat of a lower value than the natural running temperature of the engine's coolant system is as I've proved and carefully explained above... completely pointless!. The truth is for maximum engine efficiency the target fully open temp rating of a thermostat should exactly match the highest natural operating temperature the cooling system is designed to reach at idle on a hot day with the rad fans running.
And in the case of a Chimaera that figure is 88 degrees...
Thems the facts boys
Is there an accurate(ish)way of checking what temp stat is fitted without removing it?
Obviously you can check a stat is working by feeling the hose temp getting hot suddenly when it opens, but anyway of gauging the temp ?
Would rover gauge reading when hose starts to get hot be accurate (just thinking about delay in feeling temp change on the hose)
Obviously you can check a stat is working by feeling the hose temp getting hot suddenly when it opens, but anyway of gauging the temp ?
Would rover gauge reading when hose starts to get hot be accurate (just thinking about delay in feeling temp change on the hose)
Edited by WokingWedger on Thursday 1st December 12:38
bobfather said:
Very simple answer.
The heater matrix on full heat increases the temperature of air flowing through it by a set amount, say it adds 20degC.
If the outside air is 22degC, the heated air will be 22 + 20 so the hot air into the car will be 42degC.
If the outside air is 5degC, the heated air will be 5 + 20 so the hot air into the car will be 25degC.
Interesting, but the air termperature doesn't change much on a single day on a short journey.The heater matrix on full heat increases the temperature of air flowing through it by a set amount, say it adds 20degC.
If the outside air is 22degC, the heated air will be 22 + 20 so the hot air into the car will be 42degC.
If the outside air is 5degC, the heated air will be 5 + 20 so the hot air into the car will be 25degC.
So, again, if you are sitting in traffic and the temp gauge is reading say 70C, the air output of the heater is hot. Then when you get up to say 40mph, the temp gauge drops to 55C, the heater output drops to warm. That cannot be attributed to ambient air temp changes.
You are saying that the gauge is wrong and the coolant hasn't actually dropped in temp, it's just the gauge.
What I am saying is, the coolant temperature has dropped, so the gauge is correct and does reflect what is happening with the coolant temperature.
I agree that the gauge may not quite be calibrated correctly so say 55 is actual 60 and 90 is actually 95 but it's not far out.
I think the comments from others on the thermostat opening temp is probably the answer here and the noe fitted is too low.
Powers fitted an 82 degree stat when they built my engine. The fans are under ECU control and the temp has never gone above an indicated 95 even on a hot day sitting in traffic.
In this recent cold weather it indicates 70 degrees on the motorway (in the outside lane of course where its cooler
)
In this recent cold weather it indicates 70 degrees on the motorway (in the outside lane of course where its cooler
)I had the same problem with mine, thought the thermostat was stuck open. I opened it up and voila - no thermostat! I stuck a new one in and it's been fine ever since. It still drops a bit in coller weather but doesn't go straight down into the blue like it did before when moving.
Jase.
Jase.
I'd change the sender if I were you and see what happens. Otherwise I'd change the thermostat. If it were me I'd either get a genuine Rover item or at the very least from a reputable cooling brand like BEHR, Wahler, Waxstat or Calorstat. I've had a number of pattern thermostats give me more trouble than they are worth (i.e, cooling more than what I removed!).
I'd also get a good thermostat gasket. Alot will not seal around the thermostat itself meaning water will seep past the thermostat into the radiator without allowing the water to warm
. Modern gauges are damped but with the right 'stat an old car shouldn't have it's gauge moving about all over the place either I even have two older cars as proof (if not more).
-MGB GT:
I fitted a QH stat when doing a coolant flush and then fitted a Smiths Capillary dual gauge. Once it warmed up the gauge barely moved any more than 3-5 degrees over 82 degrees C, whether it was hot or cold.
-Triumph Stag:
I fitted the correct footed thermostat into it (by Calorstat) and that barely move above in the weather conditions either.
That car had amazing heaters, and in the summer with the new 'rad it didn't overheat.
-Mini 998:
That I thought was damped, but it was a tiny gauge! That gauge never moved once it warmed up!
-Mazda MX-5 Mk1 1.6:
With a genuine Mazda 'stat that gauge looked just like a modern gauge ; it never moved.
-Porsche 944 S2:
With a First Line thermostat put in when the engine was swapped the gauge was all over the place! With a genuine Porker 'stat (at a massive £3 more and a BEHR item ; it look far better made as well!) gauge didn't really move. OK, it went from 84 degrees to around 93, but that was about it. No the massive peaks people here mention./
I'd also get a good thermostat gasket. Alot will not seal around the thermostat itself meaning water will seep past the thermostat into the radiator without allowing the water to warm
QBee said:
Have you not noticed how your Audi, BMW, Mercedes, Saab, Lexus, whatever goes up to 90 degrees almost straight away and stays exactly there whether it be 3 degrees or 30 outside, and motorway or traffic jam?
A 21st century car's temperature gauge has only got three positions - off, fine or f
ked.
It's only purpose is to tell you that much.
Disagree with that to a large extent A 21st century car's temperature gauge has only got three positions - off, fine or f
ked. It's only purpose is to tell you that much.
. Modern gauges are damped but with the right 'stat an old car shouldn't have it's gauge moving about all over the place either I even have two older cars as proof (if not more).-MGB GT:
I fitted a QH stat when doing a coolant flush and then fitted a Smiths Capillary dual gauge. Once it warmed up the gauge barely moved any more than 3-5 degrees over 82 degrees C, whether it was hot or cold.
-Triumph Stag:
I fitted the correct footed thermostat into it (by Calorstat) and that barely move above in the weather conditions either.
That car had amazing heaters, and in the summer with the new 'rad it didn't overheat.
-Mini 998:
That I thought was damped, but it was a tiny gauge! That gauge never moved once it warmed up!
-Mazda MX-5 Mk1 1.6:
With a genuine Mazda 'stat that gauge looked just like a modern gauge ; it never moved.
-Porsche 944 S2:
With a First Line thermostat put in when the engine was swapped the gauge was all over the place! With a genuine Porker 'stat (at a massive £3 more and a BEHR item ; it look far better made as well!) gauge didn't really move. OK, it went from 84 degrees to around 93, but that was about it. No the massive peaks people here mention./
Edited by SebringMan on Thursday 1st December 14:13
WokingWedger said:
Is there an accurate(ish)way of checking what temp stat is fitted without removing it?
Obviously you can check a stat is working by feeling the hose temp getting hot suddenly when it opens, but anyway of gauging the temp ?
Would rover gauge reading when hose starts to get hot be accurate (just thinking about delay in feeling temp change on the hose)
Thoughts ?Obviously you can check a stat is working by feeling the hose temp getting hot suddenly when it opens, but anyway of gauging the temp ?
Would rover gauge reading when hose starts to get hot be accurate (just thinking about delay in feeling temp change on the hose)
Edited by WokingWedger on Thursday 1st December 12:38
Taylormj4
Maybe it's a case of your thermostat sticking open, or not being there at all!
As others have said, the thermostat is there to help get your engine up to temp ASAP.
But suppose it is always open. Then the car would generally take longer to warm up.
As you drive along on these cold winter days the cold air flow through the radiator will cool the engine water temp down as the thermostaat will not shut the flow of water to the radiator. Thus making the whole water system cooler.
As you said your temp gauge is working and showing the drop in water temp, the air feels cooler from the heater, etc..
But when in traffic the engine water temp would rise to the temp that the otter switch would turn on the fans. The fans would draw cool air through the radiator cooling the water until the otter switch turned them off. The thermostat will always be open in these conditions.
Maybe it's a case of your thermostat sticking open, or not being there at all!
As others have said, the thermostat is there to help get your engine up to temp ASAP.
But suppose it is always open. Then the car would generally take longer to warm up.
As you drive along on these cold winter days the cold air flow through the radiator will cool the engine water temp down as the thermostaat will not shut the flow of water to the radiator. Thus making the whole water system cooler.
As you said your temp gauge is working and showing the drop in water temp, the air feels cooler from the heater, etc..
But when in traffic the engine water temp would rise to the temp that the otter switch would turn on the fans. The fans would draw cool air through the radiator cooling the water until the otter switch turned them off. The thermostat will always be open in these conditions.
Gassing Station | Chimaera | Top of Page | What's New | My Stuff