Running cold on the motorway... Thermostat..?

[450Nick]

I seem to have a bit of a cold running problem at the moment with my Chim. I have a supercharger kit and performance mods, as well as an act ally rad so it should run hot if anything... It runs up temp nice and quick and stays there at low speed running, but in this cold weather on the motorway, the temp is dropping right down to 60/70 degrees... Does this mean that the thermostat is stuck open and the cooling system is working too well..? I'm hoping it just needs a new stat...

[MGJohn]

450Nick said:

I seem to have a bit of a cold running problem at the moment with my Chim. I have a supercharger kit and performance mods, as well as an act ally rad so it should run hot if anything... It runs up temp nice and quick and stays there at low speed running, but in this cold weather on the motorway, the temp is dropping right down to 60/70 degrees... Does this mean that the thermostat is stuck open and the cooling system is working too well..? I'm hoping it just needs a new stat...

Those I would regard as classic signs of a Thermostat wearing or worn out slow to close or not close fully. A good test for me with any petrol engine is to come down a long decline ( plenty of those in the nearby Cotswolds where I live ) on a closed throttle. In my cars that would soon see the temperature gauge needle drop down towards cold.

This time of year with lower temperatures soon reveals a worn thermostat. Both the PRT ( Pressure Relief Remote Thermostat ) in my MG ZT and the one in my son's 213,000 mile Rover 620ti do exactly as you and I have described.

I have replaced the PRT in my MG ZT and now have a nice warm car again.

[Sardonicus]

If your still using the TVR fitted sensor location then the extension is getting cooled and is not your true engine temp. in other words is to far away from the engine coolant and telling porkies being forward facing and away from any heat soak/sponging when moving hardly surprising really.

[jamienshelly]

Merry christmas all
This is happening to ours, but temp is staying at 70 on a run, I have a large bore stat and the heater is lovely when in traffic but when on the move and the gauge reading 70, it is getting cool inside (especially with the roof off) I believe its a 72 degree stat, so sounds about right. I may have to use an 84 in cold months and the 72 in the summer.
I think my diagnosis and stat specs are right

[Sardonicus]

Jamie probably 75 and 82 is stock TVR, I have only ever used a Wahler 75 and suits my warmer use, car generally drives at about 80 consistantly when moving when ambients are warm/hot, I also don't use the stock temp sensor location.

[TVRJAS]

I had temperature running issues about 6 months ago when on longer trips the gauge would drop to 55-60 and loose my warm air from heater.

TVR Power installed an 82 deg thermostat and now on long trips sits at 70 but have nice warm air through the vents.

[Sardonicus]

TVRJAS said:

I had temperature running issues about 6 months ago when on longer trips the gauge would drop to 55-60 and loose my warm air from heater.

Now that's the kind of activity you would expect from a failed stat alright.

[TVRJAS]

Sardonicus said:

TVRJAS said:

I had temperature running issues about 6 months ago when on longer trips the gauge would drop to 55-60 and loose my warm air from heater.

Now that's the kind of activity you would expect from a failed stat alright.

Just dug the bill out and it was actually in April.

If i came to standing traffic the gauge would rise to the point of the fans cutting in just over the 100 mark and hot air could be felt through the vents.

Within minutes of being on the move again i could visually see the gauge dropping to below 60 and the hot air would drop with it.

Since the 82 deg has been fitted it's never once dropped below 70 after it's warmed up,and now get the hot gear knob feeling that i used to get when first buying the car.

[jamienshelly]

Not sure what make the stat is but it as the high flow/large bore one from the 'clever' parts supplier.
I think that the lower opening of the stat is keeping the coolant at that temp when on the motorways and the like, I think i will try a higher temp one and see how it fairs in the warmer weather.
I have just had a light bulb moment, could it be i dont have a splitter on the front and the air flow around the engine is providing extra cooling?
Just a punt but it may be worth visiting B&Q and fitting one