[mefforddk]

So I was coming up I5 Thursday and I noticed that while in some top and go traffic that my car's temperature was at the 11:00 position and and holding. No big deal since that is within the normal margins. Once I started moving again the temp dropped to nominal (8:00 pos). Then the next morning anytime I came to a stop the temp immediately rose to 11:00 pos and would drop to nominal once I started again. When I checked the coolant tank the water appeared to be blackish in color versus a typuical murky green. I checked the oil stick for signs of water, but no issue there. I fear that I have a head gasket that has blown and water is leaking into the coolant. I plan on analyzing more this morning. Any thoughts out there?



Keith Mefford

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[sp4149]

Keith,

Before I determined I had a head gasket failure, the coolant tank had been stained so badly with a blackish grunge that I thought the coolant was at normal levels when the tank as actually empty. I overheated in a parking lot due to lack of coolant. probably warping the head slightly; the head was resurfaced when the head gasket was replaced. It took a lot of effoprt and cleaner to get the grunge out of the coolant tank. I never saw traces of water in the oil. but when I saw the cloud of steam out of tail pipe when I started it up; the conclusion was inescapable. I had similar symptoms to yours of fluctuating temp gages when driving and not, etc..., no coolant leaks on the ground, but periodic coolant losses.

There are past discussions of my head gaskets travails on 968.net.forums.



On the bright side, you appear to have diagnosed the problem far sooner than I did, and may not need head resurfacing. BTW my head gasket failed at 78K.



-sp4149

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[sp4149]

When our 968 overheated it was on I5 at Carlsbad. Maybe the problem is driving on I5. <img src="/forum/images/smilies/968/rolleyes.gif" class="smilie" alt="" /> -sp4149

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[mefforddk]

What is the black grunge from? I have had periodic coolant losses also, but not much. I'll look for steam coming out of the exhaust as well. My car has 112K miles on it so far.



Keith

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[sp4149]

I assumed it was oil or carbon blowing from the cylinder into the coolant passages, floating to the top of the coolant and collecting in the tank. After the head gasket replacement, it hasn't returned. I probably started the car 10 or 15 different times over a couple of weeks before I saw the steam cloud, it lasted about 15 seconds then disappeared. The car was towed to a shop a couple of days later. And I believe the failure was between the 3rd and 4th cylinders. At your mileage you might considering renewing the head, in addition to the resurfacing of the head on our engine, 9 of 16 valves were replaced, variocam was fine.



-sp4149

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[968 Cab]

Sounds like you have oil in the coolant tank. Pull the dipstick and the yellow oil fill cap and look for thick "chocolate milkshake" - that's a sign of water in the oil. Same with the coolant cap when it is cold. If you dont have the milkshake on the dipstick or oil filler cap, but have it on the coolant cap, it's probably the oil cooler seals that are leaking and getting oil into the coolant.



In either case, you gotta fix it - oil seals can be a DIY project - there are a few kits out there.



Clean out the coolant tank by removing it from the car and using lots of Dawn detergent / hot water flushing cycles. It works.

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[mefforddk]

I checked the dipstick and the oil looks fine. So you think that the oil cooler seals are leaking into the coolant line. Hmm. I have noticed a small oil leak around one of the fittings on the oil cooler. Maybe I should try and rebuild that first before I tear the top end down. Sure is a lot quicker and cheaper.



Keith Mefford

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[flash]

many shops now have an analyzer than can determine if you have any contaminants in the coolant, and what they are - costs about 100 bucks - did it on the jeep back when i suspected a head gasket leak

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[sp4149]

While you might have an oil cooler leak, I don't think it explains the cooling symptoms or loss of coolant. If your head gasket is just starting to go you may not have a lot of coolant forced into the cylinders, however if the engine is brought to operating temp and then shutoff overnight the next morning you may find coolant on one of the plugs. Not as precise as a test, or as quick, but it is cheap.

On another post, another owner felt pretty strongly that coolant loss while running indicated a head gasket failure while coolant loss after stopping was due to coolant fan switch failure (or a relay) shutting the fans down when the engine was turned off. On the 968 I wasn't losing any coolant after stopping (it wasn't overflowing) but on the 944 it dumped the reservoir after stopping. If you aren't dumping the coolant thru the overflow, or leaking thru a bad waterpump seal or hose, burning coolant is the remaining likely possibility. I'm now kind of sensitive to loss of coolant problems with these cars; I don't think the oil cooler seal problem would explain the loss of coolant. It is possible you have two problems.

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[mefforddk]

I'm sure some coolant dumped on the 5 because I could smell the distinct odor. That is what actually alerted me to look at the gauge and noticed it was running above nominal. I also noticed a small wet spot underneath the car once I pulled in the driverway the first time this occured. Good point about the coolant loss, I am not sure where I am lossing it though. But I see no signs of water in my oil.



I think what could be happening is that I have been loosing very small amounts of coolant over time and then I hit a point when the car low on coolant, then ran hot and boiled some out of the coolant tank. However, this is the first time I have had the blackish water appear in the coolant tank, so it is at the point that either the oil cooler or head gasket is leaking enough to blow stuff back through the coolant system.

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[sp4149]

I could smell the coolant too, I just couldn't find any on the ground.

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[sp4149]

[quote name='mefforddk' date='Aug 27 2006, 12:34 PM']I'm sure some coolant dumped on the 5 because I could smell the distinct odor.  That is what actually alerted me to look at the gauge and noticed it was running above nominal.  I also noticed a small wet spot underneath the car once I pulled in the driverway the first time this occured.  Good point about the coolant loss, I am not sure where I am lossing it though.  But I see no signs of water in my oil. 



I think what could be happening is that I have been loosing very small amounts of coolant over time and then I hit a point when the car low on coolant, then ran hot and boiled some out of the coolant tank.  However, this is the first time I have had the blackish water appear in the coolant tank, so it is at the point that either the oil cooler or head gasket is leaking enough to blow stuff back through the coolant system.

[right][post="25627"]<{POST_SNAPBACK}>[/post][/right][/quote]

Keith,

Have you made any progress on the overheating/coolant loss?



-sp4149

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[Tom in Austin]

One simple thing that will lead to temperature swings on the gauge is air in the system. Might be worth eliminating that as a possibility by gently backing off the bleeder bolt with the engine at operating temp and seeing if you get any bubbling.

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[mefforddk]

I have been monitoring the water level and temperature. Seems that I might have a sticking thermostat, because the temp rises up after running for 10-15 minutes when I stop on the 5 and then drops down once I get moving. Doesn't repeat again. I'll check for air. Question is "how is air getting in the system?"



No time to do anything yet. Someone hit me last week in the Valley. Right on the right rear wheel and down the skirt. Wheel is chewed up and the skirt is marked up realy nicely. Luckly I saw the guy pulling out from my right. I locked up the brakes and turned to the left. Otherwise we would have hit nose to nose.



I'm taking it to 1st class Auto off Van Nuys Tuesday for repair.

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[mefforddk]

I got the car back from the body shop Thursday. I got the head off today. The head gasket looks like it was breaking down in several areas, but mainly around the oil passages. I noticed that the overall head gasket is discolored from water.



I'm going to take the head to be rebuilt and re-surfaced, if needed, next week. Anyone with a recommendation in te LA area let me know.



While that is underway I'm putting on new brakes, rotors and struts. Boy is my wife going to kill me when she sees the bill.



Mefforddk

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[Bob Kovacs]

I have some come coolant loss and can smell coolant occasionally, so now I'm thinking about a possible head gasket replacement. If so, do the head bolts get replaced on this car or can they be reused?



--Bob

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[Tom in Austin]

On the subject of head bolts, since these are studs, is there any special technique for removing the head nuts without loosening the stud? Similarly, when you put it all back together, how do you torque the bolts without the stud turning?

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[sasilverbullet]

After the head comes back, check how much was milled off. You can buy thicker head gaskets to make up the difference.



Not doing this WILL increase the compression ratio a little - so be careful not to increase the compression too much.

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[mefforddk]

[quote name='Tom in Austin' date='Oct 9 2006, 09:13 AM']On the subject of head bolts, since these are studs, is there any special technique for removing the head nuts without loosening the stud? Similarly, when you put it all back together, how do you torque the bolts without the stud turning?

[right][post="26774"]<{POST_SNAPBACK}>[/post][/right][/quote]



I did not experience the studs from turning when I removed the nuts. They seemed to be mounted pretty solid.

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