MachSchnell

OK, after feeling like I had totally solved my overheating issue with a nice flush and fill, I checked my water level this morning to find the overflow tank virtually dry. So, I freaked, filled it, and planned on taking it down for a leakdown today (put off until tomorrow)...after spending too much time reading rennlist posts at work on the subject, I'm totally confused as I have only 1 or 2 of the symptoms that would indicate HG failure...list as follows:

Pros:
Coolant is disappearing to nowhere - I can't find any indication of external leaks...this is obviously the biggest reason I'm thinking HG

Slight yellow sludge in oil fill tube (however, having read some of the posts on the subject, I DO take very short trips to work - under 3 miles total/day)

What I suspect to be slightly higher water pressure even when cold (not huge, but definitely more than I would expect opening the cap when cold

Some bubbling (but it did fade after short time running car with cap off reservoir) of coolant as it returned to tank while running engine at a steady 3000rpms...this condition did seem to go away as the coolant level would drop as throttle was engaged, and tank was topped off

Cons:
No froth on oil dipstick - as above, a little sludge in the filler, but none in the oil that I can find

No white smoke at all...in fact, no smoke at all..to me, this is the biggest question mark, as I can't even get white smoke under full boost (not the smartest thing to do, I know, but I had to check)

The only other things I could think of were possibly:

Head lift requiring retorquing of head? (But wouldn't it smoke?)

Elec Water Pump is dead...possible but unlikely leak at speed but not idle?

Oil cooler/filter connection (no indications from what I read on the 924/44/51/68 lists, no oil in coolant that I can detect)

If anybody has suggestions, or could quantify their experience with HG issues as they relate to some of my symptoms, I would greatly appreciate it so I have a bit more ammo when taking it to the shop tomorrow.

Car is 89, 79k miles, Autothority II and 3" test pipe

Mucho grassy ***

Jason

IanM

I dunno...that coolant has to be going somewhere!! If it's not getting into your oil, then it pretty much has to be getting into your combustion chamber(s). Try taking out your spark plugs and see if one or more of them are clean and shiny (ie. water in cylinder). And try to shine a light down the sparkplug holes, and see if the tops of any pistons are clean and shiny, as opposed to the normal black and crusty. Good luck.

MachSchnell

Crap, I was thinking that I was going to do that, and in the rush of getting home and actually being able to post, I forgot. I'll be doing that soon, but if anyone has other suggestions, I'd love to hear them!

Jason

B Hayes

Are you getting a puddle under your car after it has been sitting for a while? Similar thing happened to me in my high mileage 86 951 (196k). My coolant level would drop and I had no idea where, but there was a little puddle under the car. I found a crack in the cooling hose that runs in front of the turbo (not visible by looking... it runs vertical in car)and it only opened as the pressure built after shutdown. I was lucky to find it as the crack in the hose did not shoot coolant all over the engine compartment. It is worth a shot.... I ended up pulling my cylinder head to find it(and replaced all the hoses), but it was not needed in my case. The hoses around the turbo take a beating....and it may be worth a shot to check.

MachSchnell

I wish! I'd be delighted to find a puddle...unfortunately, I've found that my car has no major leaks...there's (as expected) a bit of oil buildup on the undertray, but other than that it's pretty dry under there. On a less optimistic note, I've also realized that Porsche uses some sort of non-standard spark plug sizes, and unfortunately mine doesn't work...anybody have a suggestion/recommendation for the appropraite craftsman or comparable part to get these suckers out?

Jason

Dave951M

There are only a couple of spark plug sizes, I think either a 7/8, 13/16 or 15/16 will fit.

I think your headgasket is blown. When you check your plugs you'll probably find at least one, maybe two are super clean and shiny. Classic symptom of a blown headgasket, not an unusual failure mode either. The most difficult to determine is a hg blown only as compression across #2 and 3. There is no oil/coolant mixing and no loss of coolant or oil, or either in the exhaust. It usually manifests by rough running, can be diagnosed by a compression/leakdown check. Good luck.

Dave

MachSchnell

Well, I guess I'll just have to be antsy and apprehensive until tomorrow, none of the parts stores around here are open so I'm stuck without a matching spark wrench. I'm just lamenting the fact that I haven't had the car 2 weeks and now I'm staring full HG replacement (having belts and water pump done while he's in there even though they were done within the past 3k miles)

Damn I wish I had a garage to work in!

Keep your fingers crossed for me, pray it's some sort of stupid thing I overlooked...or at least that the motor holds out until I have a viable place to work on it.

Jason

Steve Lavigne

[quote]Originally posted by JasonECW:
<strong>Well, I guess I'll just have to be antsy and apprehensive until tomorrow, none of the parts stores around here are open so I'm stuck without a matching spark wrench.</strong><hr></blockquote>

There should be a spark plug wrench in the toolkit.

MachSchnell

*smacking head*

Damn, I wish I was smart. Course if I was smart I probably wouldn't have bought a car with 80k miles prone to HG failures with nearly retarded maintenance costs ;o)

Here's to stupidity and fun cars!

Jason

Sloth

We had a situation with a 3L 951 track car where coolant was being lost. There was no smoke out the back and no puddles. The engine would just run hot and lose fluid to somewhere. Upon removal of the head, the HG was in decent shape. However, one of the headstuds had come loose in the block and could not take more than 7-10ft lbs of torque (compared to the prescribed 50lbs). We think that this may have been the cause.

HTH. <img src="graemlins/bigok.gif" border="0" alt="[thumbsup]" />

Brian Morris

You can lose coolant out the overflow tank if the water system becomes pressurized from a lifting head or a blown HG. This usually only happens under high boost. The cylinder pressure escapes past the HG into the water jacket, pressurizes the water system, and blows the coolant out the overflow tank. No white smoke, no coolant in oil (or not much).

A common trick is to reroute your overflow hose into a clear soda bottle to see what you catch.

--Brian Morris
89 951

Wormhole

[quote] Some bubbling (but it did fade after short time running car with cap off reservoir) of coolant as it returned to tank while running engine at a steady 3000rpms...this condition did seem to go away as the coolant level would drop as throttle was engaged, and tank was topped off <hr></blockquote>

Sounds like the system was not properly bled.
There may have been air still trapped in the system.

John

951Tom

If the oil cooler seals have never been done, that would be my first guess since you have no visible leaks. 79K miles & 13 years is a lot for 2 little rubber o-rings in a turbo car AND next to the headers. Your symptoms sound exactly like mine. I was losing coolant and had no milk-shake gunk anywhere accept for a little under the oil cap. The seal kit was low $$$ too...around $30.

MachSchnell

Diagnosis: Grim!

Well after nearly wetting myself with joy when my mechanic called and told me the leak-down came back A-OK with under 5% across all 4 cyls, I was crushed when he called back after pressurizing the cooling system to find that the head gasket had blown IN of all things...apparently the coolant loss was due to a small leak on decompression/intake stroke, which was minor enough to create no smoke, so that under heavy driving there was virtually no loss, but at idle (which I was doing an awful lot of lately, since the turbo H20 pump died) it was pulling it in just a hair, and losing coolant slowly. Thus no water in oil other than minor blowby water, no oil in water, and generally no major symptoms. Unfortunately, this will cost me a pretty penny, but at least I'll have new belts and water pump if they don't look great when the front upper cover is off, and a widefire. It's also a bit comforting to know that the HG held up to the 15psi fine, just that we suspect an air bubble in the coolant may have superheated causing the blowout. Bummer, but hell, sh*t happens. Just wanted to let everyone know the problem, and I guess warn that the symptoms may not be there, but the problem might.

Jason