North American Turbocoupe Organization



blown head gasket -- now what?
EricVH Offline
Member
#1
I finally resigned myself to checking the compression for my no-start condition, and got:
cyl 1: 75 psi
cyl 2: 75 psi
cyl 3: 160 psi
cyl 4: 160 psi

I'm not sure why it still wouldn't at least fire on cyl's 3 & 4, but either way I'm pretty sure I'm looking at a blown gasket.

Any other possibilities I might be missing??

What kind of secondary damage is likely to have happened, caused by a blown gasket? If I replace the gasket, is there anything else I'm going to have to rework?

What's the resale value of an 88 TC after a fixing a blown head gasket?

I'm kinda guessing that there's a cooling passage involved, because I haven't been able to keep the radiator full for a while. I was hoping it was just a leaky hose, but now.... But since both 1 & 2 are low, maybe it's just a blowout between the cylinders, and not a cooling passage?
stock (mostly) '88 TC, slowly deteriorating....
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Pete D Offline
Administrator
#2
Sound like you have 2 problems, the HG and the coolant leak. The leak may have been a contributing factor to the blown HG. You need to fix both.
Pull the head and have it checked for cracks, Sometimes around the exhaust seats. If a crack goes through to the water jacket, that is a sure leak. You need a shop to perform a good pressure check on the head. Both the head and the block face need to be checked for flatness. If the head is cracked this presents an additional problem. Some cracks can be repaired but not all places can deal with it. It may be cheaper to find a different head. Keep us posted.

See http://turbotbird.com/techinfo/Head_Gask...Gasket.htm
Pete Dunham


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EricVH Offline
Member
#3
Sigh.

Is it possible that the block is cracked, or just the head?

How do you check the block for flatness? I'm guessing it takes a little more than just putting a straight-edge across it....

I don't have a way to get the block out, except to have it towed to a shop and have them do it. And having the car towed from my house just seems -- embarrassing. I can take the head to a shop, but if I can check the block myself, I'd rather do that. Guess I can rent a hoist, but, still, I'd rather not have to go down that path. Even if I got it out I don't have a way to take it anywhere.
stock (mostly) '88 TC, slowly deteriorating....
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Pete D Offline
Administrator
#4
It may be neither. It could be hose(s), the water pump or even the metal lines rusted, radiator.

You need to do head gasket and the head has to come off. Have it checked out. The head is more likely to be cracked than the block, but the leak could be other things. Head gaskets do give out on these car and heads are not necessary cracked when it happens.
Take it one step at a time.
You can check block face flatness your elf with a good straight edge and a set of feeler guages. A good straight edge is a metal one not beat crap. It is not a wooden one that came from the county fair.

The flatness of the head or block should be not more than 0.003" in any 6" length and not more than 0.006" overall. Place the straight edge diagonally across the length of block face . Do both diagonals.
Pete Dunham


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EricVH Offline
Member
#5
OK, well, I did it. Last weekend I replaced the head gasket. Maybe I'll post some pictures, but it was just a straightforward breech in the gasket between cyl's 1 & 2.

I pretty much followed the tech article as a guide, but it wasn't very complicated. I had trouble getting the oil line out of the turbo; and I loosened the exhaust manifold support (?) from the block instead of loosening the exhaust downpipe bolts.

Also, there was no exhaust manifold gasket.... Not sure why not. I'm the 3rd owner, but I'm pretty sure the manifold has never been off before. It never seemed to be a problem. But I went ahead and put the new one on, anyway.

I checked the block & head for flatness, cracks, etc, and didn't find any problems. There was some rust on the head bolds between 2 & 3, but nothing too bad.

After I got it back together, compression was 150, 150, 160, 150.

Unfortunately, it didn't start right away. Turns out I also needed new plugs and coil. But now it's running great! Feels good to be on the road again!
stock (mostly) '88 TC, slowly deteriorating....
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Not B Anymore Offline
Administrator
#6
Glad you got 'er up and runnin' again!

FYI - these cars did not come with a gasket between the head and exhaust manifold. They burn out and cause leaks after a while.
Brian Leavitt
'86 TC 5-Speed -- MS2x w/COP | 83 lb. injectors | T3/T4 50 Trim Stage 3 .63AR | Full 3" Exhaust - No Cat | Motorsport FMIC | Ranger Roller | Ported E6 | Walbro 255HP | Kirban | 20psi | 120-amp 3G | 8.8" 3.55 rear | '03 Cobra Wheels
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EricVH Offline
Member
#7
Hmmm, that's good to know.

Should I get rid of it now, while it's easy to pull out? Or leave it in until it fails, and scrape it off?
stock (mostly) '88 TC, slowly deteriorating....
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Not B Anymore Offline
Administrator
#8
If you have the motivation, I'd go ahead and remove it and replace it with a THIN film of high temp rtv. That'll just take up any gaps if your head and/or manifold is not 100% flat.
Brian Leavitt
'86 TC 5-Speed -- MS2x w/COP | 83 lb. injectors | T3/T4 50 Trim Stage 3 .63AR | Full 3" Exhaust - No Cat | Motorsport FMIC | Ranger Roller | Ported E6 | Walbro 255HP | Kirban | 20psi | 120-amp 3G | 8.8" 3.55 rear | '03 Cobra Wheels
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EricVH Offline
Member
#9
Hmmm, I don't know if I'm THAT motivated. Pulling out a gasket is one thing, but making enough room to put on a layer of RTV would take a bit more disassembly than I think I want to tackle.
stock (mostly) '88 TC, slowly deteriorating....
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