Duff thermostat?

[A900ss]

Just picked up my first TVR this evening, a 450 Chimaera (photos tomorrow).

It was 130 miles away and mostly motorway. Car drove like a dream and all was good apart from water temperature.

It was cold this evening but at an 80mph cruise the water temp was only 60 degrees. As soon as I come off the motorway onto normal roads and around town in went upto about 75 degrees. The heater was throwing out loads of heat.

Feels like a thermostat that is stuck open to me but would like your thoughs?

If it is the thermostat, what is the replacement of choice?

Thanks

[paul2000]

i have a grith 500 i don, t think you have much if any thing to worry about

[jojackson4]

The heaters are very good
Look for chimpofdarkness stat mod on here

[BountyHunter]

A900ss said:

It was cold this evening but at an 80mph cruise the water temp was only 60 degrees. As soon as I come off the motorway onto normal roads and around town in went upto about 75 degrees. The heater was throwing out loads of heat.

Feels like a thermostat that is stuck open to me but would like your thoughs?

those are classis stuck/missing stat symptoms.

its not unheard of for brand new ones to not work so dont forget to check it before fitting (though even thats no guarantee - the brand new one I fitted to the 24v S worked on testing and then failed after just a few days)

[TV8]

I expect it is just the gauge misreading.

Switch the car on from cold and feel the pipe away from the stat. If it gets warm quickly and slowly increases in temperature, then your stat is open. If it takes a reasonable period of time to get warm, then gets hot very quickly, it's working fine.

[Mr Supercharged]

The temperature gauge is so inaccurate it's unreal! My advice is to make sure you don't have an airlock anywhere, check the level in the radiator looking through the bleed screw, the level in the swirl tank in front of the engine (this should be full to the top) and the level in the tank mounted on the inner offside wing which should be about half full. If all of these are ok, I would borrow an ECU mate from someone, this can be plugged into the 14CUX and will let you see what the ECU Temperature sender is reading. You can then compare this against your gauge and this will prove my point. If you are still unhappy, I would suggest fitting the lower temperature 74 degree thermostat by racetech direct:

http://www.racetechdirect.co.uk/tvr-car-part-e2027...

http://www.racetechdirect.co.uk/tvr-car-part-e422a...

very good, just used myself

[BountyHunter]

innacurate guage or not - it still sounds like its getting much colder on a run.

for the sake of a tenner or so id personally just change the stat regardless.

Edited by BountyHunter on Friday 1st March 23:10

[A900ss]

BountyHunter said:

innacurate guage or not - it still sounds like its getting much colder on a run.

for the sake of a tenner or so id personally just change the stat regardless.

Edited by BountyHunter on Friday 1st March 23:10

I agree with the above. Although the heater was great even when on the motorway and only showing 60 degrees, it was noticeable that the heater got warmer when the temp gauge went up to 75 degrees.

[Dodsy]

If your heater was great on the motorway the stat is probably fine. The dash gauge is not accurate. My stat failed / weeks ago and i didnt get warm air for 10 miles , after 25 motorway miles it was warm ish and the dash gauge was barely above the stopper.

[ChimpOnGas]

A900ss said:

BountyHunter said:

innacurate guage or not - it still sounds like its getting much colder on a run.

for the sake of a tenner or so id personally just change the stat regardless.

Edited by BountyHunter on Friday 1st March 23:10

I agree with the above. Although the heater was great even when on the motorway and only showing 60 degrees, it was noticeable that the heater got warmer when the temp gauge went up to 75 degrees.

They all do this A900ss, your problem is not the thermostat.

In fact you do not actually have a problem at all, well other than your gauge under reading at speed.

Like I say they all do this.

It's because of how TVR chose to fit the sender, when the matched sender came from the gauge manufacturer TVR realised the thread did not match the hole for the temp sender in the Range Rover inlet manifold.

So they made an adapter, this adapter & the new position TVR chose to place it is the reason your gauge reads low at speed.

This is due to to the sender not getting proper water flow over its entire body, the sender is cooled by the faster moving cold air, as you increase your speed the gauge starts to read low.

The truth is your coolant temperature is fine & there is absolutely nothing wrong with your thermostat whatsoever.

You can tell this because your heater is working correctly, even with the heater working correctly there will always be a small increase in cabin temperature as you slow because cold external air is no longer being forced into the passenger compartment.

To resolve the "low reading gauge at speed" issue you need to do the Range Rover temp sender mod, this simply utilises the much better positioned Range Rover temp gauge sender with your TVR gauge.

To trim the Range Rover sender to the gauge you simply need to fit a tiny resistor, the value of this resistor may vary slightly from car to car but typically ends up around the 170 ohm mark.

I recommend you buy a 0-500 ohm variable resistor to allow you to trim its value perfectly, you can use your radiator fans as an indicator, they should come on at 85 degrees, so simply tune the variable resistor so the gauge reads 85 just at the point the fans kick in.

Now watch your newly trimmed gauge, it should read 91/92 ish as the fans go off, the system should then cycle to give you an average idle temp of just over 85 degrees.

On the move is where you are going to see the difference though, your gauge will now show the correct 80 degrees even at speed on the coldest day.

So you see it's just a sender to gauge matching exercise, & taking the reading from the far better positioned Range Rover temp sender.

The best thing of all is you don't even need to buy the Range Rover sender, have a close look & you will see its in your manifold already, in fact it's been sat there doing nothing since the day your car left the TVR factory.

More about this easy, cheap & rewarding little modification here:

http://www.pistonheads.com/gassing/topic.asp?t=118...

[David Beer]

http://pistonheads.co.uk/gassing/topic.asp?h=0&amp...

[Julesprivate]

There is definitely some truth in the 'they all do that sir' observations and the RR mod is a good one.


At speed on the motorway quite a bit of fresh air can find its way into the cabin making the heater seem less efficient, plus there is a pretty big radiator up front getting a lot of very cold air shoved through it, it sometimes feels a little too efficient on cold days. Combining those things means you will get less warmth into the cabin.

I suspect the thermostat is probably OK, but it might be worth changing as you have just bought the car so don't know how long it has been in there, or indeed if there is one in there at all (the PO of my S had removed the stat from that before I bought it!)

I'd be inclined to do the RR mod.... I plan on doing it to mine sometime in the near future as my gauge works precisely as you describe..

Hey look you have an excuse to tinker already LOL

[A900ss]

Jules,

As I got the car for a good price, I am strongly tempted to just book it into Neil Garners for a major service anyway. Save me the job of doing it!!!!!

Alternatively, do it myself and then get the front stonechips resprayed.....

Dithering again.....

[jojackson4]

Do it your self and save your cash for paint

[Taffer]

Holy thread resurrection maybe, but didn't think it worth creating another on a similar topic.

My recently acquired Chim 400 has been fine until a recent road trip to the Isle Of Wight. In slow moving traffic (<30mph) the temperature has steadily climbed above 90C, with eventual loss of oil pressure and stuttering/cutting out. Above 50mph, temp. reduces to 70-75C and oil pressure is fine (I drove home from Pembroke to Glasgow with no issues until off the motorway near my house). Now, within 10 mins of driving at slow speeds the temp. is rising above 90C so unless I get on a NSL road or motorway quickly, it's not a happy bunny at all.

The radiator fans both come on above 90C so otter switch seems OK, swirl pot is full and expansion tank is 1/3 full when cold. Am I right in thinking this is most likely a wonky thermostat or could it be something else?