Correct Thermostat/ Cooling system help
Discussion
New to ownership and enjoying my 4.0litre but a few niggles to sort
Having identified that the thermostat is failed open or missing I have had a new one supplied by the reputable David Gerald who obviously I trust to know his stuff. It is 82°
I want just to be sure that this is correct or that the other elements of my system we working ok prior to fitting.
The thing I have noticed is that my fans come on at around 75° indicated on the gauge with the car stationary.... So will this work in harmony with an 82° thermostat?
either
because the temperatures are sensed in different places,
Or
Do I need a different thermostat with a lower opening temperature
Or
Do I need to/ can I adjust the temperature at which the fans are triggered?
As an aside but not my main query at the moment...
I have had a new radiator recently and also note that the design of this system is a little odd with the expansion tank very low down it is always full having ("burped") the car with a top up via the separate swirl pot o satisfy myself of getting the air out of the system. Possibly as my thermostat seems open this doesn't help retain a volume of water higher up.
Any experience or advice or explanation greatly received
Thanks
Having identified that the thermostat is failed open or missing I have had a new one supplied by the reputable David Gerald who obviously I trust to know his stuff. It is 82°
I want just to be sure that this is correct or that the other elements of my system we working ok prior to fitting.
The thing I have noticed is that my fans come on at around 75° indicated on the gauge with the car stationary.... So will this work in harmony with an 82° thermostat?
either
because the temperatures are sensed in different places,
Or
Do I need a different thermostat with a lower opening temperature
Or
Do I need to/ can I adjust the temperature at which the fans are triggered?
As an aside but not my main query at the moment...
I have had a new radiator recently and also note that the design of this system is a little odd with the expansion tank very low down it is always full having ("burped") the car with a top up via the separate swirl pot o satisfy myself of getting the air out of the system. Possibly as my thermostat seems open this doesn't help retain a volume of water higher up.
Any experience or advice or explanation greatly received
Thanks
BJ8MGCTVR said:
New to ownership and enjoying my 4.0litre but a few niggles to sort
Having identified that the thermostat is failed open or missing I have had a new one supplied by the reputable David Gerald who obviously I trust to know his stuff. It is 82°
I want just to be sure that this is correct or that the other elements of my system we working ok prior to fitting.
The thing I have noticed is that my fans come on at around 75° indicated on the gauge with the car stationary.... So will this work in harmony with an 82° thermostat?
either
because the temperatures are sensed in different places,
Or
Do I need a different thermostat with a lower opening temperature
Or
Do I need to/ can I adjust the temperature at which the fans are triggered?
As an aside but not my main query at the moment...
I have had a new radiator recently and also note that the design of this system is a little odd with the expansion tank very low down it is always full having ("burped") the car with a top up via the separate swirl pot o satisfy myself of getting the air out of the system. Possibly as my thermostat seems open this doesn't help retain a volume of water higher up.
Any experience or advice or explanation greatly received
Thanks
Welcome aboard mate.Having identified that the thermostat is failed open or missing I have had a new one supplied by the reputable David Gerald who obviously I trust to know his stuff. It is 82°
I want just to be sure that this is correct or that the other elements of my system we working ok prior to fitting.
The thing I have noticed is that my fans come on at around 75° indicated on the gauge with the car stationary.... So will this work in harmony with an 82° thermostat?
either
because the temperatures are sensed in different places,
Or
Do I need a different thermostat with a lower opening temperature
Or
Do I need to/ can I adjust the temperature at which the fans are triggered?
As an aside but not my main query at the moment...
I have had a new radiator recently and also note that the design of this system is a little odd with the expansion tank very low down it is always full having ("burped") the car with a top up via the separate swirl pot o satisfy myself of getting the air out of the system. Possibly as my thermostat seems open this doesn't help retain a volume of water higher up.
Any experience or advice or explanation greatly received
Thanks
Your cooling system should be filled via the Header tank
Then topped up via the expansion tank
The expansion tank could be mounted on your inner wing but should have a cap similar to this one. You should only fill the expansion tank HALF full to allow for expansion of the coolant, any more than that and the coolant will be dumped on the floor when it gets hot.
The temperature shown on the gauge in the car is an indication only and cannot be trusted as an accurate measure of coolant temperature.
The best way to test what temperature your fans kick in is to use a handheld infra red thermometer and measure the temperature at/near the otter switch when the fans cut in.
Hope this helps
Ged
Welcome.
Definitely sounds like something isn't reading the temperature correctly. It could be that the fan sensor is turning the fans on too early (p[resume it's the standard temp switch and not controlled by an aftermarket ecu?) or your Temperature gauge is reading wrong?
The thermostat you've been given is a stock opening at 82 degrees, and even the lower temp operating fan control switch should be coming in at 92 degrees and shutting off at 87. Stock kicks in at 95 and shuts off at 88 degrees.
http://www.racetechdirect.co.uk/tvr-sensors-switch...
I know these units can fail, but only heard of them not cutting the fans in, or at a hotter temp, rather than cutting in early.
I'm sure someone with way more knowledge than me will chip in to help.
What is it that makes you think the thermostat isn't opening? I would have thought the engine would overheat very quickly, and the fans would not come on at all?
I had issues with a lower temp thermostat being fitted, in colder weather on the motorway the temp would sit at 60 degress and the heater would be pretty cool, and in hot summer traffic the temp would rise to between 100-110 degrees before the fans cut in (albeit with a knackered leaky old stock rad)
I went with a stock 82 degrees thermostat, replaced the rad with an alloy one and went for the lower fan cut in switch at 92 degrees cut in.
The result is a nice toasty heater in winter with needle on the gauge never going below 82 degrees, and sitting in heavy traffic, the gauge never goes beyond a smidge over 90 degrees before the fans cut in and out maintaining the temp.
Since the change over, I've never had a problem.
Regarding the constant burping, I would have thought the pressure cap on the expansion tank should stop the leakage, even in it's sitting a bit low (do you have any pics so the guy's on here can comment?)
Have you checked all the hoses for a slight leak. I had some corrosion on the top pipe of the swirl pot. It wasn't leaking fluid, but was letting air into the system as the alloy had furred up under the rubber hose.
Easily sorted by removing the hose and carefully removing the build up around the pipe.
Lastly, silly question, but are you topping up the coolant via the brass nut at the top of the swirl pot?
Hope this helps
Definitely sounds like something isn't reading the temperature correctly. It could be that the fan sensor is turning the fans on too early (p[resume it's the standard temp switch and not controlled by an aftermarket ecu?) or your Temperature gauge is reading wrong?
The thermostat you've been given is a stock opening at 82 degrees, and even the lower temp operating fan control switch should be coming in at 92 degrees and shutting off at 87. Stock kicks in at 95 and shuts off at 88 degrees.
http://www.racetechdirect.co.uk/tvr-sensors-switch...
I know these units can fail, but only heard of them not cutting the fans in, or at a hotter temp, rather than cutting in early.
I'm sure someone with way more knowledge than me will chip in to help.
What is it that makes you think the thermostat isn't opening? I would have thought the engine would overheat very quickly, and the fans would not come on at all?
I had issues with a lower temp thermostat being fitted, in colder weather on the motorway the temp would sit at 60 degress and the heater would be pretty cool, and in hot summer traffic the temp would rise to between 100-110 degrees before the fans cut in (albeit with a knackered leaky old stock rad)
I went with a stock 82 degrees thermostat, replaced the rad with an alloy one and went for the lower fan cut in switch at 92 degrees cut in.
The result is a nice toasty heater in winter with needle on the gauge never going below 82 degrees, and sitting in heavy traffic, the gauge never goes beyond a smidge over 90 degrees before the fans cut in and out maintaining the temp.
Since the change over, I've never had a problem.
Regarding the constant burping, I would have thought the pressure cap on the expansion tank should stop the leakage, even in it's sitting a bit low (do you have any pics so the guy's on here can comment?)
Have you checked all the hoses for a slight leak. I had some corrosion on the top pipe of the swirl pot. It wasn't leaking fluid, but was letting air into the system as the alloy had furred up under the rubber hose.
Easily sorted by removing the hose and carefully removing the build up around the pipe.
Lastly, silly question, but are you topping up the coolant via the brass nut at the top of the swirl pot?
Hope this helps
BJ8MGCTVR said:
New to ownership and enjoying my 4.0litre but a few niggles to sort
Having identified that the thermostat is failed open or missing I have had a new one supplied by the reputable David Gerald who obviously I trust to know his stuff. It is 82°
I want just to be sure that this is correct or that the other elements of my system we working ok prior to fitting.
The thing I have noticed is that my fans come on at around 75° indicated on the gauge with the car stationary.... So will this work in harmony with an 82° thermostat?
either
because the temperatures are sensed in different places,
Or
Do I need a different thermostat with a lower opening temperature
Or
Do I need to/ can I adjust the temperature at which the fans are triggered?
As an aside but not my main query at the moment...
I have had a new radiator recently and also note that the design of this system is a little odd with the expansion tank very low down it is always full having ("burped") the car with a top up via the separate swirl pot o satisfy myself of getting the air out of the system. Possibly as my thermostat seems open this doesn't help retain a volume of water higher up.
Any experience or advice or explanation greatly received
Thanks
Having identified that the thermostat is failed open or missing I have had a new one supplied by the reputable David Gerald who obviously I trust to know his stuff. It is 82°
I want just to be sure that this is correct or that the other elements of my system we working ok prior to fitting.
The thing I have noticed is that my fans come on at around 75° indicated on the gauge with the car stationary.... So will this work in harmony with an 82° thermostat?
either
because the temperatures are sensed in different places,
Or
Do I need a different thermostat with a lower opening temperature
Or
Do I need to/ can I adjust the temperature at which the fans are triggered?
As an aside but not my main query at the moment...
I have had a new radiator recently and also note that the design of this system is a little odd with the expansion tank very low down it is always full having ("burped") the car with a top up via the separate swirl pot o satisfy myself of getting the air out of the system. Possibly as my thermostat seems open this doesn't help retain a volume of water higher up.
Any experience or advice or explanation greatly received
Thanks
Edited by PJ57 on Wednesday 29th April 12:04
Ged beat me too it with my slow arse typing 
Thanks for the quick replies.
I now feel confident to change the thermostat and then see how it works.
To be clear diagnosis of thermostat stuck open ie doesn't heat up beyond 50-60° driving motorway speeds on cold mornings ever due to cooling effect over new radiator and an open cooling circuit.
However when stationary it will heat up to around 70 indicated.
When it's more like 20 outside air temp and cars already been driven it sits happily around 70° even on the move.
Then when stopping temp rises a little without the air flow and then fans kick in at about mid 70's
Possibly have a small leak from the where the hose connects to the top of the swirl pot (one with the brass stopper) which is where i topped up. Incidentally this pipe always feels empty when I first approach the car. The expansion tank (lower one near radiator) is always brimming even when cold (obviously can't open it when hot)
I now feel confident to change the thermostat and then see how it works.
To be clear diagnosis of thermostat stuck open ie doesn't heat up beyond 50-60° driving motorway speeds on cold mornings ever due to cooling effect over new radiator and an open cooling circuit.
However when stationary it will heat up to around 70 indicated.
When it's more like 20 outside air temp and cars already been driven it sits happily around 70° even on the move.
Then when stopping temp rises a little without the air flow and then fans kick in at about mid 70's
Possibly have a small leak from the where the hose connects to the top of the swirl pot (one with the brass stopper) which is where i topped up. Incidentally this pipe always feels empty when I first approach the car. The expansion tank (lower one near radiator) is always brimming even when cold (obviously can't open it when hot)
BJ8MGCTVR said:
Thanks for the quick replies.
I now feel confident to change the thermostat and then see how it works.
To be clear diagnosis of thermostat stuck open ie doesn't heat up beyond 50-60° driving motorway speeds on cold mornings ever due to cooling effect over new radiator and an open cooling circuit.
However when stationary it will heat up to around 70 indicated.
When it's more like 20 outside air temp and cars already been driven it sits happily around 70° even on the move.
Then when stopping temp rises a little without the air flow and then fans kick in at about mid 70's
Possibly have a small leak from the where the hose connects to the top of the swirl pot (one with the brass stopper) which is where i topped up. Incidentally this pipe always feels empty when I first approach the car. The expansion tank (lower one near radiator) is always brimming even when cold (obviously can't open it when hot)
Your indicated temperatures don't sound anything out of the ordinary. I now feel confident to change the thermostat and then see how it works.
To be clear diagnosis of thermostat stuck open ie doesn't heat up beyond 50-60° driving motorway speeds on cold mornings ever due to cooling effect over new radiator and an open cooling circuit.
However when stationary it will heat up to around 70 indicated.
When it's more like 20 outside air temp and cars already been driven it sits happily around 70° even on the move.
Then when stopping temp rises a little without the air flow and then fans kick in at about mid 70's
Possibly have a small leak from the where the hose connects to the top of the swirl pot (one with the brass stopper) which is where i topped up. Incidentally this pipe always feels empty when I first approach the car. The expansion tank (lower one near radiator) is always brimming even when cold (obviously can't open it when hot)
Do you mean the large hose from the thermostat housing to the Header tank or the small hose from the Header tank to the Expansion tank?
Either way, the leak needs sorting out.
Once done, just check the temperature at/near the otter switch when the fans cut in. Is your otter switch in the base of the Header tank or in the upper Left corner of the rear face of the Radiator?
There is a possibility that it's because the gauge temp sensor can get cooled by airflow when at motorway speeds, giving a false low reading. Just had the stat replaced in mine and gauge temp still plummets at speed.
Best way to check stat is start engine from cold and feel rad pipes - should be stone cold (apart from near the manifolds!) until engine reaches temp. Heater should be producing warm air well before rad gets anything.
Best way to check stat is start engine from cold and feel rad pipes - should be stone cold (apart from near the manifolds!) until engine reaches temp. Heater should be producing warm air well before rad gets anything.
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