Tom M'Guinn

Does your cooling system overflow and/or develop air in the system despite multiple attempts to vent it? And have they pressure tested it. I'd be hesitant to pay for a HG job based on the car simply running warmer and that one test.

Markoneus

Yeah, no more air in the system, and no overflow in the coolant system, just a slowly rising level of pressure that hovers just below red. I wonder, too, if there's still another explanation. But every other theory I throw at them they say isn't the problem...

boerge

Did you change the radiator switch?

Markoneus

Yes, Radiator switch was replaced 3-4 months ago when another mechanic noticed the fan wasn't running when the car was at a stop, only at highway speeds.

Tom M'Guinn

The switch cannot distinguish between idling in the garage and cruising at freeway speeds -- it can only sense temperature. The car runs cooler on the freeway because lots of air is moving though the radiator at 70mph or the like. There is also no practical way for your mechanic to know if the fans are on or off when the car is moving down the freeway -- he will just see the temps getting cooler from all the airflow through the radiator.

You do not have classic 944 head gasket symptoms based on your various posts. It's certainly possible your HG is leaking, but normally you will get a pressurized cooling system and eventual air pockets and overflow, and your mechanic's diagnostics do not seem well informed. I would get a second opinion before letting this mechanic change the head gasket. Radiators become less efficient over the years, and can get externally (leaves/bugs) or internally (calcium from tap water, goo from antifreeze) blocked. Waterpump pulleys can slip on their shaft and/or belts can slip on the pulley. Temp gauges/sensors can be out of calibration. Waterpump internal bypass gaskets can fail and bypass coolant inside the pump, etc., etc.

Markoneus

Update: so, they tried something new, and measured the hydrocarbons in the coolant at cold start, and THEN it was high. 150 ppm when cold, dipping down to 115 when hot (presumably because when engine was hot, the gasket expanded and sealed up a bit. But yes: they were confident now it was the head gasket.

I authorized the procedure, and upon opening it up, sure enough, the gasket was blown between cylinders 1 & 2. (They kept the gasket to show me.) The gasket was about 65k old, but more than 10 years, and prob more like 12. So, all in all, not unexpected that it would blow, esp since this engine is pretty heavily modded and putting down 290 rwp, not stock 217. Sad to have to pay for this big of an operation when it would have been preferable to just do a thermostat, but it is what it is. Hopefully this is the last big bill for a while...

lart951

of coursed it was the head gasket, at first when you said a metal gasket sandwiched between cardboard i thought it was a MLS head gasket which is practically indestructible, but then you said it was a wildfire and I thought oh no Yosemite, j/k. Now seriously the widefire is a myth, it doesn't offer more protection than stock unless you have a o-ringed head and block. If your mechanic suggest widefire you know he doesn't know nothing about 951's. Second changing the blown gasket WON"T solve your issue, first you need to find out what cause the blown gasket, 65k miles is not a lot of miles.

My friend I have seen many guys coming to this board and ignore the advice of guys who built, fix and dealt with 944 on daily basis. They come back and said "well my mechanic said this and that " and they fail, one the most prominent was LFA951, we advice that guy to change mechanics but he was a DB and ignored the warnings, he ended up selling his car as scrap.

Things you need to check

Tuning, is your car properly tuned, are you running proper air fuel ratios?
do you have wide band 02 sensor? an aftermarket boost gauge?

Can you answer those questions?

Tom M'Guinn

If they give you the gasket back, take a few pics and post them up. My fingers are crossed that your car is all fixed up and running well, but I'm not sure how to interpret someone saying the gasket blew "between cylinders 1 & 2." On the normal turbo motor (unlike the later 104mm motors) the cylinders are free standing tubes inside the block and each is sealed entirely separately with no common sealing points in between -- so not sure what it means to say it blew between two cylinders. Hopefully just a choice of words thing. A picture would be worth a thousand words though... The ultimate test will be when the cars is back together to see if it now runs cool. Did you have the valves refreshed while it was apart? 65k is a bit early for that, but if the head was off anyway...

Scott H

I don't have anything to add except that every time I come into this thread I get this song stuck in my head:

lart951

Love that song

Tom M'Guinn

Any update? Did the new gasket fix the problem?

Markoneus

Yep, finally got the car back. And yes, it was the head gasket. They kept it for me, and showed me where it failed--in the 2nd cylinder, facing the first. Pic below. It wasn't a big failure, or a split in the ring, but it had failed enough so pressure was escaping (where my finger is) into the coolant area, pressurizing it, causing it to run hot.

But the other problem is that it was NOT a WideFire gasket, it was just a stock one. So perhaps it's no wonder that it failed, with all the extra boost the car was now generating. I'm about to call the guy who installed it (Blair Talbot in NH) if he can explain why he swears he put in a WideFire but it was actually just stock. I don't know if he just remembered it wrong, or actually lied. but I have no idea why he wouldn't have put in a beefier gasket, esp since it's only $40 more or so, out of $2500 job, so no real incentive to cheat the customer there. But yes, the car's temp problem is completely solved w/ the new WideFire gasket, the gauge sits rock-solid just above the lower 1/3 marker and rarely budges. It even felt a bit stronger, too, which the guys attributed to it now having new valve guides put in. (the head was went to a machine shop, but they said the head & valves were in great shop, but the guides were shot. They suspected they might have been the original guides, too, even though Blair insisted he replaced those, too.) So, not trying to nec. trash Blair's rep, but I'm a bit miffed for now, and will report back after I've spoken to him. My dad (who did all the work w/ him) always spoke highly of the guy, so want to give him a chance to explain it.

Only other note is that the guys told me not to really max out the engine on that first 500 miles or so, let everything settle before trying to see if it still gets 17 lbs boost and they've put all the parts back together correctly. It now has 1000 miles on it since the new gasket, and I put my foot into it a little deeper, but I got a weird high-pitched/ whirring sound from the turbo (I think) at about 5000 rpm that sounded wrong/ never heard before, but there was too much traffic for me to try to get there again and replicate it. A bit worried not everything w/ the aftermarket turbo & wastegate etc got put back together correctly again. (theories?) More soon.

hosrom_951

I see what you did there

Had that issue with widefires before