Normal Running Temperatures
Discussion
I dont want to doubt the information in the bible, but is the normal temp running round town correct at 95deg max?
When warm the temp goes over this briefly whilst in traffic, when back moving again, the temp drops back to 70 to 80deg.
This appears to be a major issue with these cars, where should I start?
Both fans are working, although I have not checked what temp they cut in at.
Water level is ok.
I suppose the next step would be to check the Radiator for blockages.
PS my cars a 4.0 96 Chimaera
Thanks in advance.
Chris
When warm the temp goes over this briefly whilst in traffic, when back moving again, the temp drops back to 70 to 80deg.
This appears to be a major issue with these cars, where should I start?
Both fans are working, although I have not checked what temp they cut in at.
Water level is ok.
I suppose the next step would be to check the Radiator for blockages.
PS my cars a 4.0 96 Chimaera
Thanks in advance.
Chris
Mine runs really low when cruising 50 - 60,
when on it it goes to maybe 70 max (with lots air flow), when in traffic first fans come on around 80,
second at <90 - and come back to 80+ if hot day. Mine very really gets above 90. and comes down very fast once on the move again. I have had the whole cooling system changed at 30k service (should have been done at 36k - but i'd prefer it done at ever 6k - worth it I think.)
Jon 98 500 Chimera
when on it it goes to maybe 70 max (with lots air flow), when in traffic first fans come on around 80,
second at <90 - and come back to 80+ if hot day. Mine very really gets above 90. and comes down very fast once on the move again. I have had the whole cooling system changed at 30k service (should have been done at 36k - but i'd prefer it done at ever 6k - worth it I think.)
Jon 98 500 Chimera
quote:
...When warm the temp goes over this (95) briefly whilst in traffic temp drops back to 70 to 80deg.
Chris,
Mine did almost exactly the same as yours (up untill today...)
Both fans stopped working at the same time leaving me with a slightly too hot car and about ten seconds of steam from the header tank. (Note that I was in traffic and had not been hammering the car at all).
I regularly drive in traffic and this is the first time the fans didn't come on.
Rooted around, checked fuses, reseated relays but to no avail.
Where is the temp. sender and can it fail? Anyone?
(In the interim, I have ordered the 2-speed fan setup from www.mod-wise.com ) (Oh yes, and the bible but it has not arrived yet).
Harrigan
After posting this (wrong order really 
) I did a search on other listings, there is loads of info to read on a boring sat night, been out all day with the hood down though, so should not complain!
So first thing in the morning, is to go & check the system for air locks rather than blockages, starting with the swirl tank, then the radiator, fingers crossed till then??
Harrigan
If I still have an engine at the end of this week, might see you at Chatsworth.
Thanks all
Chris
) I did a search on other listings, there is loads of info to read on a boring sat night, been out all day with the hood down though, so should not complain! So first thing in the morning, is to go & check the system for air locks rather than blockages, starting with the swirl tank, then the radiator, fingers crossed till then??
Harrigan
If I still have an engine at the end of this week, might see you at Chatsworth.
Thanks all
Chris
quote:
I dont want to doubt the information in the bible, but is the normal temp running round town correct at 95deg max?
When warm the temp goes over this briefly whilst in traffic, when back moving again, the temp drops back to 70 to 80deg.
This appears to be a major issue with these cars, where should I start?
Both fans are working, although I have not checked what temp they cut in at.
Water level is ok.
I suppose the next step would be to check the Radiator for blockages.
PS my cars a 4.0 96 Chimaera
I think your car could well be normal. The bible says 90-95 in traffic. 80 when crusiing. Sounds pretty normal to me. Also bear in mind that the guages are not that accurate and providing the fans switch in at around 85-95 degrees all should be well.
The thing that is the most important is... a fan override switch so that you know if the otter switch has tripped and can override it if something goes wrong.
If it ain't broke don't fix it. If you run the car cooler than this, the ECU does not go into its adaptive mode and adjust its settings for your car so instead of running on the best settings (usually) the car just gets the default.
Steve
www.tvrbooks.co.uk
Pretty sure my car has 2 speed fans - one comes on then if in constant traffic and the temp is still going up (i.e. hot day) the other seems to come in, then temps always go down to sensible levels. Any doubts, I'd get the whole system drained and properly filled (I still use main dealer - with plenty of anti-freeze to keep the boiling temp down). My ideal is crap until warm, i.e. flying from 0-1000 until warm - this must be to do with the not to suffisticated! brain on the ECU.
quote:
Pretty sure my car has 2 speed fans -
If you have a Rover V8 engined car then you haven't unless someone has fitted a Mod-Wise kit or similar. The ECU does not control the fans, a simple thermostatic switch does that. The Cerbera and later cars do take care of the fan switching though.
steve
www.tvrbooks.co.uk
Todays observations
Slight leak from top of radiator, fixed with radweld until radiator repairs replacement is possible. Looking at the front of the rad, it looks like its been driven through a gravel trap without the front grill on, at some stage in its life, maybe not that bad, but it was my first impression.
Fans cut in at about 82deg, temp continues to climb & they do cut back out whilst the temp is over 82deg, I would have thought that they would have stayed on till it was below 82deg again. They only stop for about a minute, should this happen? Temp seems to be much more stable today. Steve, you could be right, I might just be getting paranoid. Still not sure about the fans cutting out whilst over 82deg though.
Hope we have a cool summer!!
Slight leak from top of radiator, fixed with radweld until radiator repairs replacement is possible. Looking at the front of the rad, it looks like its been driven through a gravel trap without the front grill on, at some stage in its life, maybe not that bad, but it was my first impression.
Fans cut in at about 82deg, temp continues to climb & they do cut back out whilst the temp is over 82deg, I would have thought that they would have stayed on till it was below 82deg again. They only stop for about a minute, should this happen? Temp seems to be much more stable today. Steve, you could be right, I might just be getting paranoid. Still not sure about the fans cutting out whilst over 82deg though.
Hope we have a cool summer!!
Out today in mine, just cruising around 4-50mphish, glanced at the temp gauge and it was nearly 90, so it can get up there even if moving along as normal.
Mind you, once on the A1 and doing a bit over the NSL
swiftly came down to 75ish where it happily remains on a normal British day (ie, not hot) 
Mind you, once on the A1 and doing a bit over the NSL
swiftly came down to 75ish where it happily remains on a normal British day (ie, not hot) Unless you've had a lower temp otter switch fitted, I'd be surpised if the temp really was as low as 82 to cut in the fans. As Steve says, take what the coolant temperature guage says with a large pinch of salt. The absolute numbers don't mean or matter too much. More important is to be able to spot when you're getting readings outside your car's normal range for the conditions.
Also, when you blast up the motorway the coolant does indeed drop back to about 70. But don't assume the engine is cool, coz if you look at the oil temp it will show the engine is blazing away. You certainly won't be at risk of boiling off the coolant, but if your cooling system were suddenly to fail, you have got bugger all time to stop.
There are two opposing processes happening. There is a heat exchanger between the engine and the coolant that heats the coolant, and a heat exchanger between the coolant and the air that cools the coolant (the radiator, of course). The rate of flow of heat in any exchanger is a function of (a) the efficiency of the heat exchanger and (b) the absolute difference in temp across the exchanger.
Now, the radiator's efficiency improves enormously with speed, so the coolant can loose heat without needing a massive temp difference between the coolant and the air when you are on the move. BUT the efficiency of the engine to coolant exchange is pretty much constant. So when the engine is working hard and therefore needs to loose a lot of excess heat, it can only do so by increasing the temperature difference between the coolant and itself.
Basically this means that if you are driving quickly enough that the radiator is working well, then the coolant temp guage tells you bugger all about the temperature of the engine. It can show a steady 70C, and when rolling along at 50mph, the engine will be running cool too. But if you are crusing at 90mph, the coolant will still be at 70C, but the oil temp may well be 100+C.
Also, when you blast up the motorway the coolant does indeed drop back to about 70. But don't assume the engine is cool, coz if you look at the oil temp it will show the engine is blazing away. You certainly won't be at risk of boiling off the coolant, but if your cooling system were suddenly to fail, you have got bugger all time to stop.
There are two opposing processes happening. There is a heat exchanger between the engine and the coolant that heats the coolant, and a heat exchanger between the coolant and the air that cools the coolant (the radiator, of course). The rate of flow of heat in any exchanger is a function of (a) the efficiency of the heat exchanger and (b) the absolute difference in temp across the exchanger.
Now, the radiator's efficiency improves enormously with speed, so the coolant can loose heat without needing a massive temp difference between the coolant and the air when you are on the move. BUT the efficiency of the engine to coolant exchange is pretty much constant. So when the engine is working hard and therefore needs to loose a lot of excess heat, it can only do so by increasing the temperature difference between the coolant and itself.
Basically this means that if you are driving quickly enough that the radiator is working well, then the coolant temp guage tells you bugger all about the temperature of the engine. It can show a steady 70C, and when rolling along at 50mph, the engine will be running cool too. But if you are crusing at 90mph, the coolant will still be at 70C, but the oil temp may well be 100+C.
Fantastic day out, drove out to Henley, Marlow etcetera, saw a bunch of other TVR's, most acknowledged my 
In terms of normal running temperatures, steady cruising at just over (
) 70 results in a steady temperature of 80 degrees. Fans still not cutting in...
I suspect the otter switch. Haven't tested the fans by shorting out the wires to the switch yet, nervous about the 12v PD I measured across them...
Nothing to touch the TVR experience, heat and all...
H
In terms of normal running temperatures, steady cruising at just over (
) 70 results in a steady temperature of 80 degrees. Fans still not cutting in... I suspect the otter switch. Haven't tested the fans by shorting out the wires to the switch yet, nervous about the 12v PD I measured across them...
Nothing to touch the TVR experience, heat and all...
H
quote:
12V is fine
But the otter switch only switchws the fan relays so the current is veru low indeed. If in any doubt, use a low value fuse (1-3 AMP) to short out the connection.
The otter switch needs to be working correctly even if you have the Mod-Wise 2-stage system because without it you never get the full fan air flow and without that the car will eventually overheat anyway.
My own priority would be:
Get the otter switch working correctly.
Fit a fan override with tell tale LED (Mod-Wise do one of those).
Consider a 2 stage circuit.
Steve
www.tvrbooks.co.uk
Oh pants
. No chance of damage there then.
I remember a happy time at school when a teacher accidently shorted a car battery through a two foot piece of copper wire and then turned back to the class.
Step 1: Wire droops
Step 2: Insulation blown off forming perfect mushroom cloud
Step 3: Wire glows bright pink
Step 4: "Err, sir, uhm, your desk is on fire"
Step 5: Teacher tries to unplug connectors with bare hands ... silly.
. No chance of damage there then. I remember a happy time at school when a teacher accidently shorted a car battery through a two foot piece of copper wire and then turned back to the class.
Step 1: Wire droops
Step 2: Insulation blown off forming perfect mushroom cloud
Step 3: Wire glows bright pink
Step 4: "Err, sir, uhm, your desk is on fire"
Step 5: Teacher tries to unplug connectors with bare hands ... silly.
During my trials with cooling mods i was amazed what speed you have to be doing to keep the temp from creeping up. If you are doing 70 mph and begin to slow down, the cooling of the rad becomes less effective, as we know. Without an air splitter, its 55mph when the temp begins to rise. With an air splitter you can go down to 40-45 and the rad is effective.
However with half speed fans going,you can go down to 30mph with the same cooling as doing 55mph.Of course this was not tested using the temp guage, that really is only to give an idea of the high and lows.
Iam sure the Chimera is better as the rad sits up rather than slopping forward.
However with half speed fans going,you can go down to 30mph with the same cooling as doing 55mph.Of course this was not tested using the temp guage, that really is only to give an idea of the high and lows.
Iam sure the Chimera is better as the rad sits up rather than slopping forward.
The temperature indications on my 500 have taken a real dive. In normal operation, the temp used to sit quite comfortably in the 80-95 bracket, with the fans kicking in at about 90. I have no reason to believe that the actual running temps have changed and the fans still operate as expected sitting in traffic etc but the gauge has taken to under-reading by about 40 degrees across the board. I don't think I have seen the temp above 55 all week and the fans operate at about 52!!!
I am assuming that I am faced with a gauge or temp sensor problem. Where do I start looking? Can the gauge be removed from the front of the dash or is it a dashboard out job?
I am assuming that I am faced with a gauge or temp sensor problem. Where do I start looking? Can the gauge be removed from the front of the dash or is it a dashboard out job?
Dashboard off to get the gauge out. If it's like mine it will be held in place by being pulled back into the dash with a u-shaped brace bolted to the back of the gauge.
However, my guess would be that your temperature sender is on the blink. The gauge just contains a couple of resistors to match the windings to the sender ... so simple its unlikely to fail.
A question for anyone out there who knows about auto electrics ... how is the temp guage winding designed??? It looks to me that the meter itself has three terminals. There appear to be two seperate coils that share a common terminal. Both have to be energised to get the needle to move. What is going on with that?
However, my guess would be that your temperature sender is on the blink. The gauge just contains a couple of resistors to match the windings to the sender ... so simple its unlikely to fail.
A question for anyone out there who knows about auto electrics ... how is the temp guage winding designed??? It looks to me that the meter itself has three terminals. There appear to be two seperate coils that share a common terminal. Both have to be energised to get the needle to move. What is going on with that?
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