The V8 Owners Forum -

Hi all,

I’ve had a good trawl over the pervious threads but still not totally sure about my coolant temps. Basically I have no issue with cooling at idle/in traffic etc, the car is easily kept cool by the elec fan. I have it set at 85°C and it stays bang on that value (fan cycles in and out no probs).

What I’m interested to know is whether I’m overcooling when cruising and at higher speeds with low load.
My gauge reads no more than 70°C during this sort of driving. I know the gauge isn’t going to be deadly accurate, but based on the correlation between the cooling fan switch setting and the gauge reading I don’t think it’s a long way out.

I can’t remember what thermostat I have in it but pretty sure it’s not as low as 70°C (can you even get them that low?), but do you think I should investigate how to increase the lower coolant temp value above 70°C?

I’m looking for a 50:50 balance regarding performance and mpg, so basically I’m after a temp to give a good compromise and certainly one which isn’t going to cause any other side effects either.

Cheers guys.
Gary.

Sounds like the thermostat is stuck open and not closing so getting to much coolant flow through the rad when crusing?

Tom.

SuperV8 wrote:Sounds like the thermostat is stuck open and not closing so getting to much coolant flow through the rad when crusing?

Tom.

Deffo worth fitting a new stat for the sake of a few quid.

Cheers Denis

Yeah I think I will stick a new stat in to be sure. I had thought it might be a stuck stat or just that with temp gauge error and some oil/sump cooling it was dropping a little bit below the stat closing temp...

What temp stat would you recommend I get chaps?

mk1storm wrote:Hi all,

I’ve had a good trawl over the pervious threads but still not totally sure about my coolant temps. Basically I have no issue with cooling at idle/in traffic etc, the car is easily kept cool by the elec fan. I have it set at 85°C and it stays bang on that value (fan cycles in and out no probs).

What I’m interested to know is whether I’m overcooling when cruising and at higher speeds with low load.
My gauge reads no more than 70°C during this sort of driving. I know the gauge isn’t going to be deadly accurate, but based on the correlation between the cooling fan switch setting and the gauge reading I don’t think it’s a long way out.

I can’t remember what thermostat I have in it but pretty sure it’s not as low as 70°C (can you even get them that low?), but do you think I should investigate how to increase the lower coolant temp value above 70°C?

I’m looking for a 50:50 balance regarding performance and mpg, so basically I’m after a temp to give a good compromise and certainly one which isn’t going to cause any other side effects either.

Cheers guys.
Gary.

Hello Storm, A wide open stuck thermostat might be your problem, BUT, if because you are getting some degree control around the 70 degree mark then you may well have a low thermostat in there. Ive heard that 70 deg stats are available for the RV8.

That may also explain why the temperature rises to 85 at idle before the leccy fan kicks in.

Reason being, (if the viscous is missing) there is no cooling function at all when the car is stationary so the stat just stats wide open..

You have not said if its Efi or carb?

If Efi then IMO 70 degrees is much too low a running temp as the system runs best at or just above 90 degrees. The fuelling would be too rich and fuel consumption - pants..

For carbs perhaps 85 degrees is a better temp, but for either - 70 deg is too low.

If you would care to read this web page, which could almost have been written especially to answer your questions,

http://www.vintagemodelairplane.com/pag ... emp01.html

you'll see whats happening. There is some more reading material here:

http://www.vintagemodelairplane.com/pag ... ing01.html

I think the PDF there-in being pertinent to your situation.

Thanks for the feedback guys. From reading that material I think I'll get a 82°C stat, put that in and see what happens.... If it solves things then great, if not then I'll look into things a little more. I may raise my cooling fan cut-in temp a little if I add this stat in.
Cheers guys!

Problem solved.... was indeed a stuck open stat... simples!

Thanks guys.