968: Blown head gasket saga...
10-07-2005 | 10:48 AM
#1
Thread Starter
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Joined: Aug 2002
Posts: 3,351
Likes: 799
From: San Antonio, Texas
968: Blown head gasket saga...
Just want everyone to learn from my mistakes - here's the saga of a blown head gasket on my 93, 968 coupe w/144,400 smiles on it:
Work being done by my friends at Jones Autowerks in San Antonio -
Monday:
1. The head gasket had failed on the bottom edge of no. 4 cylinder and was leaking coolant into the cylinder. I had white smoke out of the exhaust start about a mile from the shop - you should see how clean that cylinder is! NO carbon!
2. It was about to fail at the same spot on no.1.
3. Both the head and the block were not warped.
4. The valves were all in great shape - left those alone!
5. VarioCam blocks are both badly worn - $45 each from paragon
6. VarioCam sprockets on cams were in great shape.
7. The little sensor behind the timing belt sprocket for the cam disintegrated - will get a new one.
8. They drained the oil into a clean bucket - had some evidence of coolant. Because of this they want to do new rod bearings. So now the leaky oil pan gasket will finally get fixed!
9. There was a LOT of black gunk in the intake manifold and in the intake ports of the head. They say it's because the previous owner drove it too slow...I'll never be guilty of that!
10. Going to have the injectors cleaned.
Tuesday:
Just got of the phone with the shop. They dropped the oil pan and there was CRUD, overheated, nasty, gooey crud in the oil pan that to get out completely they had to sand blast the thing!
The rod bearings all had the coating worn off and were about to start failing...
btw, this car had never had Mobil 1 until I bought it...
The motor mounts were both squashed and broken, replaced those...
Now they're starting to put everything back together...
The shop thinks that I had water in the oil for about a week. Last Sunday I took it out for a hard drive through the hill country. I didn't overheat it, but it was a HOT day (106ish) and the temp gauge was near the upper white mark quite a bit. They think the oil and water cooked in the oil pan...
Wednesday:
Shop is getting things back together, all is going well.
Some lessons learned so far -
1. If you're loosing coolant and can't find a leak anywhere, STOP driving the car and have a shop check to see if coolant is getting in the engine!
2. A white bucket is the way to go to see if the oil is brown from coolant.
3. If you have ANY evidence of coolant in the oil, plan on replacing the rod bearings. The coating on those things gets eaten up by a little coolant. Once the coating is gone, they fail rather soon thereafter.
4. At about 120,000 miles - replace the head gasket and the variocam blocks, or at a minimum, watch the coolant level closely and if you start loosing coolant with no visible signs of leakage, then replace the head gasket.
5. You'll probably need new motor mounts also at 120,000 miles.
6. If you don't drive your car like a Porsche was meant to be driven, you will have a bunch of carbon in the intake manifold and ports.
7. If you overheat the engine, replace the head gasket. If may be okay now, but it will fail soon thereafter, it's the after part I hate...
8. And finally, like Chris Alvarado in Austin says, "Drive it like you stole it!"
Finally, it's Friday and I'm picking the car up today!!! I'll let you'all know how it runs...
Later,
Michael Sorbera
aka sasilverbullet
Work being done by my friends at Jones Autowerks in San Antonio -
Monday:
1. The head gasket had failed on the bottom edge of no. 4 cylinder and was leaking coolant into the cylinder. I had white smoke out of the exhaust start about a mile from the shop - you should see how clean that cylinder is! NO carbon!
2. It was about to fail at the same spot on no.1.
3. Both the head and the block were not warped.
4. The valves were all in great shape - left those alone!
5. VarioCam blocks are both badly worn - $45 each from paragon
6. VarioCam sprockets on cams were in great shape.
7. The little sensor behind the timing belt sprocket for the cam disintegrated - will get a new one.
8. They drained the oil into a clean bucket - had some evidence of coolant. Because of this they want to do new rod bearings. So now the leaky oil pan gasket will finally get fixed!
9. There was a LOT of black gunk in the intake manifold and in the intake ports of the head. They say it's because the previous owner drove it too slow...I'll never be guilty of that!
10. Going to have the injectors cleaned.
Tuesday:
Just got of the phone with the shop. They dropped the oil pan and there was CRUD, overheated, nasty, gooey crud in the oil pan that to get out completely they had to sand blast the thing!
The rod bearings all had the coating worn off and were about to start failing...
btw, this car had never had Mobil 1 until I bought it...
The motor mounts were both squashed and broken, replaced those...
Now they're starting to put everything back together...
The shop thinks that I had water in the oil for about a week. Last Sunday I took it out for a hard drive through the hill country. I didn't overheat it, but it was a HOT day (106ish) and the temp gauge was near the upper white mark quite a bit. They think the oil and water cooked in the oil pan...
Wednesday:
Shop is getting things back together, all is going well.
Some lessons learned so far -
1. If you're loosing coolant and can't find a leak anywhere, STOP driving the car and have a shop check to see if coolant is getting in the engine!
2. A white bucket is the way to go to see if the oil is brown from coolant.
3. If you have ANY evidence of coolant in the oil, plan on replacing the rod bearings. The coating on those things gets eaten up by a little coolant. Once the coating is gone, they fail rather soon thereafter.
4. At about 120,000 miles - replace the head gasket and the variocam blocks, or at a minimum, watch the coolant level closely and if you start loosing coolant with no visible signs of leakage, then replace the head gasket.
5. You'll probably need new motor mounts also at 120,000 miles.
6. If you don't drive your car like a Porsche was meant to be driven, you will have a bunch of carbon in the intake manifold and ports.
7. If you overheat the engine, replace the head gasket. If may be okay now, but it will fail soon thereafter, it's the after part I hate...
8. And finally, like Chris Alvarado in Austin says, "Drive it like you stole it!"
Finally, it's Friday and I'm picking the car up today!!! I'll let you'all know how it runs...
Later,
Michael Sorbera
aka sasilverbullet
10-07-2005 | 02:23 PM
#5
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Joined: Mar 2005
Posts: 722
Likes: 0
From: Norfolk,Va.
Any aluminium engine with 120,000miles is subject to (wearout) a head gasket. With every heating and cooling the engine is scrubbing the gasket material as it expands and contracts. Sounds like your shop has you ready for another 120k miles.
10-07-2005 | 02:59 PM
#6
Thread Starter
Rennlist Member
Joined: Aug 2002
Posts: 3,351
Likes: 799
From: San Antonio, Texas
It never ceases to amaze me how much knowledge is on this website! That's two things I've learned that even the gurus at my Porsche shop didn't know...
1. heating and cooling scrubs the head gasket
2. design of the 968 intake manifold produces the black gunk in it - normal
I'll explain this stuff to them this afternoon when I pick up the car...
1. heating and cooling scrubs the head gasket
2. design of the 968 intake manifold produces the black gunk in it - normal
I'll explain this stuff to them this afternoon when I pick up the car...
