333pg333

Just thought I'd throw this out there to see what previous experiences others have had.
Sean swapped over everything from the Grey car to the 'new' Black car. All the hardware and interior. One thing that we kept was the radiator from the '86 car
that is now the 'new' car.
So we go to the track and within a very few laps the car overheated radically. Up into the Red zone which it's never done before.


Things we tried:

-Removed the Thermostat to increase the amount of water in the system initially which should have slowed the heating process down. Didn't work.
-Removed the a/c condenser to free up passage to the radiator. As I have a large fmic the radiator would be getting a blocked flow, however we have had this before without overheating issues.
-Created ducting from the Vented nose panel down into the much more open radiator surface. Still overheating within 2-3 laps of a short course.

So the only things that have changed is that we previously have been running E85 for all of last year...but had run pump on previous years without high heat issues.
Also have changed the Vitesse software to the newer V Flex but without checking with John we believe that if anything the ign curve would be more advanced than what it was before so
overheating through retardation is highly unlikely.

The only other thing to consider is if the crash has had an effect on some part of the cooling system that only manifests itself under track conditions. It was very warm over the last few days here, but I would think
that if there was anything malfunctioning that even driving on the road would show some signs of overheating in this weather. Sean thinks it could be possibly the impellor being able to spin at certain rpms / load
but perhaps it's slipping or freewheeling when on the track?

Anything else you guys can think of please feel free to suggest. Just may help us speed up the process of solving it.

TexasBlake

Are you losing coolant too, or does the system remain full and still causing an overheating issue?

Personally, I would not remove the thermostat. Replace with a lower temp one..... maybe. But I wouldn't remove it.

333pg333

We run a second expansion tank setup so the coolant goes into that and then comes back to the primary one when it cools down. We also tried a 1.5bar cap.

Removing the thermostat was just something to try when at the track.

carlege

Im having a little trouble understanding the radiator status. You swapt everything from your grey car to the Black car (new) but didnt swap the radiator.

You sure the radiator isnt blocked or the system is bled properly?

333pg333

Yep that's right. Basically everything bar the radiator. We just had such a tight timeframe to do the swap and still make the meeting. Guess it could be blocked but then wouldn't it be overheating all the time then?

carlege

I would swap the radiator (not sure if it was salvageable) and go from there. It seems to be the only piece that is suspect

TexasBlake

Both fans coming on?

That's something often overlooked.

Tom M'Guinn

Sounds like the coolant is not circulating. I'd put the t-stat back in to make sure the bypass is closed, and check to make sure the t-belt is tensioned and not glazed. Don't know of any way to check if the impeller is slipping on its shaft without removing the pump, but suppose that's possible too. And, of course, keep an eye open for other signs of a bad head gasket (overheating only on boost always makes me wonder about the ol HG.)

333pg333

Both fans are coming on but not at a high speed from what I can tell.

Also as a side note the brakes had long travel after many times bleeding properly. Again, all the hardware
was swapped over inc M/C. This car doesn't have ABS but I don't think that has anything to do with it.
Glad to say that the PFCs really worked well in terms of bite, but it was hard with the long travel and then suddenly finding aggressive bite and with no ABS. Very hard to modulate without locking.

Duke

Hmm I agree that it sounds like the coolant isn't circulating.
The fans shouldn't affect the temps that much when moving. I would start with changing to another radiator first.

DeWolf

Pat,

I must have missed something....did you crunch the 944?

Scott

333pg333

Coolant seems to be circulating based on all the hoses getting hot. If there was a blockage or thermostat not opening we'd have some hoses way hotter than others, no? We've got both radiators. We'll do some comparitive tests and see what happens. It has to be something simple. Hope there's a plastic bag stuck in the present one!


Scott, yes unfortunately the Grey car was in an accident. It might re surface at a later date but for now we're in a '86 with the hardware from the '89. Living on in spirit for the moment.

Van

Are you getting "air" (steam) at the bleeder location after driving? I bet you are - and that points to head gasket blow-by...

gt37vgt

throw a can of that radiator flush stuff in dump it our try again..
do you have all the bat wing and trailing defuser installed? . are the seals at the back of the bonnet in tact?
pop the sun roof and run the heater up on to the windscreen be sure that its gets hot as the gauge goes up .
If your heater still works with the thermostat removed your raditaor is blocked

fast951

Are you using the factory temp gauge or a external one? Did you verify that the temperature is as hot as the display indicates?
I'm sure you have checked the followings, but I'll ask anyway:
- Did you bleed the cooling system and get all the air out of it?
- Did you measure the water temps on the IN & OUT of the radiator?
- How much boost were you running on pump gas?

I'm thinking either a internally clogged radiator, or a restriction in the flow.