mikey_audiogeek

Maybe base ignition curve is OK but getting too much ignition retard caused by false triggering of the KLR? That can cause overheating. EGT would show this.

333pg333

I would think if anything the ign curve would be advanced from base with the V Flex?

I'm also being told that my car was blowing some smoke. Not Black or Blue apparently.

gt37vgt

Never take the thermo stat out as the thermo stat blocks the bypass port when it opens with out it it will always by pass.
also a small hole drilled in the thermostat helps bleed the air in that area if not the thermo stat can be stiting in an air pocket .

mikey_audiogeek

I had a freewheeling pump impeller that showed some symptoms beforehand. Combined with a faulty instrument earth that coincidentally caused the temp gauge to "spike", it was a biatch to troubleshoot. The hose check did confirm the problem though. Went from fine to failed within 3 days of road use. Luckily didn't cause any motor damage.

Hope you make progress soon Patrick, sounds like you don't need any more grief! Keep at it.

Best regards,
Mike

333pg333

Taking the t-stat out was just something to try at the track to increase the amount of water being utilised at one time. Also some track guys run like this too...but I'm guessing we'll reinstall one.

Thanks Mike, but this is a doddle compared to other issues in the past so we'll find it and deal with it. Always frustrating to have to find this out when you've paid for 2 days at the track which is over 2 hours away though!! Seems to happen every year at this place. Did a h/g there last year, and the year before broke the CV bolts and had to get towed all the way home after 10 laps running in a new engine.
Happy Dayz!!

gt37vgt

with out the thermostat less water goes through the rad and more reticulates when the plunger in the thermostat moves in it blocks the bypass port ..
do you have the extension on the batwing ? that extends back to the cross meber?
944 challenge guys report cars boiling without this peice .. ..

333pg333

I thought the job that the t-stat did was block off the water from the radiator until it reached a certain temp. By removing it, it would include all the coolant in the system from the get go?

I'm not sure I've seen this extension piece to the Batwing Adam? Got any pics? Thing is, here I am running .6 to 1.1. bar and overheating a lot when I've run 1.5 bar through there on E85 before with no problems.

Dubai944

If you don't find any blockage in the radiator do a leakdown test on all cylinders with the bleeder valve open and coolant topped up. If there are any HG sealing issues you should get water bubbling out the hole. Doesn't have to be a catastrophic HG failure to still cause a problem.

Duke

The plastic under tray between the bat wing and the crossmember, don't you have it?
It's not uncommon they end up in the lost & found corner of non 944-familiar workshops..

Luis de Prat

On the stock 951, there's a plastic extension AND an aluminum tray that bolts into the crossmember.

333pg333

I've seen underneath my car so many times but in my mind's eye I just can't picture this extension to the Batwing. Perhaps I have it and think it's all part of the same thing?

Having said that, if I don't have it now, I never have. So that doesn't explain contributing to my overheating.
Sean will get a better idea over the next few days and we'll post back.

Car looks pretty sharp actually. I liken it to one of Darth's escape modules lol.

jerome951

I've run without these many times on hot track days without a problem. Yes, they should help a little, but absense of them shouldn't cause a car to overheat in 3 laps.

As others have suggested, sounds like a head gasket going bad.

Chris White

A couple of comments –
Frist – as mentioned before (and this is good advice to all!) Get the infrared thermometer – it’s a very valuable tool, especially at the track! You can check the temps all over the radiator and identify clogged areas, you can check temps in and out of the engine and rad to look for temp drops. And then you can check the temps of your calipers to see how well the brake cooling is working. I used to get the calipers on my wife’s Audi S4 up to 420 f!).
You can get these for $60 in the states!

Second – slipping impeller on the water pump is quite possible. Everything looks good on the outside…

Third – clogged radiators is also quite possible as well as a really crappy cooling system – see picture below for nightmares! Note – please don’t look if you are eating / drinking anything right now….it might make you spew on your computer!

Lastly – good to hear you are back at the track!

fast951

Assuming the MAP sensor was installed and connected to the DME, I would say boost is fine so is the ignition. If the MAP sensor was disconnected, the DME will sense it and will go into limp mode. You will know it when it does (the engine will be very lazy).

I would concentrate on the cooling system.

Van

The way the 944 coolant system works, there are 2 distinct coolant loops (one to the engine and one to the radiator). The the thermostat moves, it opens one loop, but closes the other.

When the t-stat is removed, the pumped coolant will take "the path of least resistance" - which frequently increases the flow through the radiator, but decreases the flow into the block.