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Old November 5th, 2012, 09:06 AM   #1
Rx7Kevin
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Question Cylinder leakdown test - Royal Oak

My 85 suburban SBC is starting to burn oil, blue smoke likes to come out of the passenger side exhaust. Compression is the following (only checked the passenger side bank)

cylinder 2 = 180psi
cylinder 4 = 32psi
cylinder 6 = 12psi
cylinder 8 = 182psi

so now I'm looking at making sure I just need to do a simple fix or start a winter project.

Anyone got a cylinder leakdown tester or know a place where to get it done, the truck runs and starts and drives fine, its jut not very powerful, at least it has 4.10 gears :)
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Old November 5th, 2012, 09:57 AM   #2
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What happened if it running while you remove oil cap off valve cover? Smoke coming out?

With that low compression you could had bad rings on piston or blown head gasket. How long this issues been start?
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Old November 5th, 2012, 10:34 AM   #3
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Originally Posted by MilwaukeeF350 View Post
What happened if it running while you remove oil cap off valve cover? Smoke coming out?

With that low compression you could had bad rings on piston or blown head gasket. How long this issues been start?
I haven't tried that but I will when I get home, but the issue is that the valve cover with the oil cap is on the other bank.

I'm thinking rings or stuck valve(s), as well as bad valve seals. A lot of vehicles with bad valve seals will give a good puff of oil smoke upon start up, but there is more than that going on providing those compression numbers lol.

When I pulled the plugs out on those middle cylinders there was oil on the threads. I'm still kinda putting this truck together/fixing it up. I purchased around May and I've maybe put 2000 miles on it. The engine is from another truck, its kind of a basket case so I'm not surprised if the engine will need a refresh.
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Old November 5th, 2012, 10:57 AM   #4
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think you can get them from auto zone but the point ur at it dosent really matter i know on my commpression gauge i can pull the valve out of it and hook it up to a air compresser try that if you can
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Old November 5th, 2012, 11:26 AM   #5
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I don't have an air compressor

but at least I'm not getting any coolant in the oil.

Last edited by Rx7Kevin; November 5th, 2012 at 11:29 AM.
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Old November 5th, 2012, 01:22 PM   #6
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Quote:
Originally Posted by Rx7Kevin View Post
cylinder 2 = 180psi
cylinder 4 = 32psi
cylinder 6 = 12psi
cylinder 8 = 182psi
Most likely the head gasket is blown between #4 & #6. Seen this happen in a few trucks.
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Old November 5th, 2012, 04:16 PM   #7
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Most likely the head gasket is blown between #4 & #6. Seen this happen in a few trucks.
Yeah I have 3 theories:

1. bad head gasket
2. stuck valve
3. rings are toast
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Old November 5th, 2012, 04:52 PM   #8
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Dump some oil into the spark plug hole on the low cylinder and check it again.
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