Bad Compression
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Senior User
Joined: Jan 2003
Posts: 382
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From: Prairieville, Louisiana
Bad Compression
On my 1987 5.0L 302 I have bad compression on one cylinder. I'm thinking its either blown head gasket or bad valves.
Cylinder Compression
1 150
2 150
3 155
4 160
5 170
6 165
7 160
8 30
On the number one and two cylinders it took about 7 compression strokes to reach 150 psi. One the others it only took about 3 compression strokes to reach compression. I think that is an indication of bad rings.
Can anyone help?
Cylinder Compression
1 150
2 150
3 155
4 160
5 170
6 165
7 160
8 30
On the number one and two cylinders it took about 7 compression strokes to reach 150 psi. One the others it only took about 3 compression strokes to reach compression. I think that is an indication of bad rings.
Can anyone help?
Postmaster
Joined: Jun 2003
Posts: 2,656
Likes: 5
From: shepherd
how many miles do you have. does your motor smoke when you first crank it up. if so your valve guides are worn if i were you i would rebuild the heads at a good machine shop. it does not cost much.
Postmaster
Joined: Jun 2001
Posts: 4,496
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Well you have the cylinder isolated, see if you can get a shop, or you could, bring number 8 to top dead center, blow compressed air into the plug hole and listen for where the air is coming out at. If its in the crankcase then your probably right about the rings, number 8 usually is a problem on fords, that is where the pcv valve is ran too so all the vapors/oil get dumped into that cylinder and nothing but problems arise. When you fix the cylinder compression problem you might consider redirecting the pcv hose to a more central port around the carb or intake so each cylinder gets a little of the vapors, as opposed to just one. Just a thought, later
Thread Starter
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Senior User
Joined: Jan 2003
Posts: 382
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From: Prairieville, Louisiana
When I start it and while it is running it has white smoke coming from the exhaust. I know that white smoke means oil so it could maybe have something to do with valves.
Postmaster
Joined: Jun 2001
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Sounds weird but let the white smoke hit your hand or something then smell it. If its sweet its coolant leak if not then it is normal condensation. Either way you have a larger problem with a 30psi cylinder. Let us know what you find out to be the problem with the poor cylinder compression. later
