RV8 Cooling

[philip600]

Hi Agian,
My RV8 was running at 92/94 degrees when driving which I thought was a bit too hot. It would soon creep up when in traffic etc & fans would need to be switched on.
After reading posts on here it appears that most recommend a 74degree stat so I swapped my 82 degree one at the weekend.
Went out tonight for good run to Scarborough & it is now running at 60/62 degrees according to the guage & is not happy ! misfiring etc. ( It is bl**dy cold out there tonight ! )
Stopped on way home & partially blocked rad off with cardboard & temp up to 80/82degrees, engine was alot happier.
So I was thinking of making something to partially block off rad that could easily be removed when ( if ) the weather gets hotter but wondered if you can buy a valve to fit in the top rad hose that could be controlled from the dash when driving ( like the valve to the heater ) then I could adjust it whilst driving depending on temperature & how I'm driving ?
Is this feasable & if so has anyone done this ?
Your thoughts would be appreciated
Regards Phil.

[philip600]

P.S. Forgot to say the new stat is the TVR type which has larger bore than standard. ( Still suprised how much differance it has made to running temp though ) Phil

[chedz]

Hi Phil, I've got a 74 degree stat in my Rv8 and it runs at 80 degrees in all weathers. Sounds like something is stuck open or your gauge could be wrong. I used one of the IR heat sensor guns to measure the temp of my inlet manifold and it varies quite a lot. Perhaps the stat is working but the gauge is reading too low? I don't think having to keep putting things in front of the rad is a very practical solution long term. What sort of inlet manifold do you have?

cheers

Graham

[philip600]

Hi Chedz,
The engine is running EFi not carbs so just normal RR inlets.
I did wonder about the gauge but withing 1/4 mile of partially blocking rad the engine was running superb again ( gauge now at 80/82 ) so I suspect the gauge is about right but the enging was over cooling. I would agree it would not be ideal to have to keep removing or re-fitting a shield to the front of the rad which is why I wondered about controlling the flow to the rad with an adjustable valve.
I could try a 76/78 stat but would rather have it where it can be run very cool if needed ( i.e. track days ) but restricted for normal driving.
I may be barking up the wrong tree but I'm a heating engineer by trade & it makes sense in my mind to have a valve to adjust the flow to the rad ?
Phil.

[Sidecarbod]

If your running the Rover EFI system then you are going to have to run it over 80 degrees (maybe 78 ). The reason is that the mixture enrichent does not switch off until the engine is above this temp.

I'm not sure whether blocking the rad or changing the stat is the best way to go. I guess if you can find a stat that allows your engine to run just above 80 then that would be fine.

I suspect that your gauge is accurate, your engine was running quite cool and the misfiring was due to the rich mixture.

If you are running a 3.5 lump then you can run them a bit hotter than the larger lumps without fear of cracking the block. I believe the 3.9 and to a lesser extent the 4.6 blocks were the ones the suffered if ran too hot. (I think that the "service" 3.5 blocks were a bit dodgy but I'm 100% sure on that as its been a while since I read my book on RV8's !).

At least stats are cheap so you could buy a few and mess about with them!

Isn't your valve idea just basically what a stat does?


Pete

[TINKA]

I wonder if there was something wrong with your old stat as I always used to run my old 3.9 RV8 with an 82 deg stat and never had the slightest of problems. There are other consequences to running the engine under temp for any length of time such as accelerated wear so I would not leave it running like this for very long.

[philip600]

Thanks for replies.

Yes Pete, the stat does do what a valve would but you cannot control the stat ?
I think I'll take your advice & fit a new 82 degree stat & run it to see what happens.
Will let you know what I find.
Regards Phil.

[philip600]

Hi again,
Fitted new 82 degree stat tonight & went out for run.
Temperature gauge still 60 when driving ( it's definately too cool because the heater is not as hot as it was & I can put my hand on the radiator even after a few miles. )
If I leave it ticking over it will get upto 90 degrees ( heater nice & hot )but withing 1/2mile of setting off again the temp drops back down to about 60 ?
Question is why ? any ideas ?
This only started when I swopped thermostat to lower temp one !
I also noticed that one of the plugs for a sensor on the inlet manifold was broken ( wire clip that holds it on is missing & plastic broken ) so I have put some tape round as temporary measure.
There are two together, I think the one thats broken ( slightly larger ) is the thermotime sensor ? & the other the coolant sensor, does this sound correct ?
Any help would be much appreciated.
Regards Phil.

[jonny m]

I had a similar problem when I took out a faulty stat and did without for a while.

when air passed through the rad, it cooled ALL the water in the system regardless of water/engine temp.

When I stopped, it rose, though this was due to fans wired wrong and an air lock - been advised to drill a 2mm hole in the top of the stat to help relase air when filling.

Fitted new standard stat (82deg) and runs fine now...well sort of, leaky heater matrix so bypassed and with less water in system fans on a bit more often - works OK though.

Can't see why need a lower temp stat. 82deg worked OK when in SD1, and less weight in a Cobra, so why change ?

Jon

[philip600]

Hi Jon,
I changed it because I thought it ran a bit hot ( 92ish ) but when fitted with 74 degree stat it ran too cool ( 62ish ) so fitted new 82 degree stat same as before & it's still runs too cool now ? I'm 99% sure the temp gauge is correct because as I've said the heater is not as hot as it was & I can put my hand on the rad after a good run.
Can anyone advise if it's possible that one of the sensors has gone faulty & the engine is running too rich ( hence misfiring ) & this is why engine temp is low ? is this possible ?
What is the thermo-time sensor for ?
Thought someone might have an idea
Phil.