460 problems
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Tuned
Joined: Nov 2007
Posts: 276
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460 problems
I have a '93 c/b truck that sat all summer due to not needing it and some engine problems.
i let it sit because it was going through oil and getting on one plug and fouling after about 80 miles or so.
And it would smoke from under the hood cause oil was hitting the manifold on the driver's side.( I think crankcase hose is blowing out). Going through 1-2 quarts in 20 miles.
But it didn't smoke from the tailpipe or anything.
I did have to replace the valve guide seals this spring cause the old ones were crumbled. And it did seam to help some.
Today I checked compression and it was a consistent 50-60 on every cylinder wet or dry.
Leak down test on the driver's side was letting 60psi leak up through the valve cover(tdc on #1), but not leaking on the passenger side.
The truck starts up with no problems either.
Would all my cylinders be junk, or bad valves,head/gasket?
Ot better off replacing the motor?
i let it sit because it was going through oil and getting on one plug and fouling after about 80 miles or so.
And it would smoke from under the hood cause oil was hitting the manifold on the driver's side.( I think crankcase hose is blowing out). Going through 1-2 quarts in 20 miles.
But it didn't smoke from the tailpipe or anything.
I did have to replace the valve guide seals this spring cause the old ones were crumbled. And it did seam to help some.
Today I checked compression and it was a consistent 50-60 on every cylinder wet or dry.
Leak down test on the driver's side was letting 60psi leak up through the valve cover(tdc on #1), but not leaking on the passenger side.
The truck starts up with no problems either.
Would all my cylinders be junk, or bad valves,head/gasket?
Ot better off replacing the motor?
pedant
Joined: Jan 2008
Posts: 23,576
Likes: 38
From: EXTREME southwest CT
Are you sure it's not 150-160?
it is hard to imagine your engine running on 50-60 compression numbers.
Did you do the test with the throttle wide open?
I think you would know much more if you were to do a leakdown test.
Sounds like a lot of blow by, but hard to answer given the information provided.
it is hard to imagine your engine running on 50-60 compression numbers.
Did you do the test with the throttle wide open?
I think you would know much more if you were to do a leakdown test.
Sounds like a lot of blow by, but hard to answer given the information provided.
pedant
Joined: Jan 2008
Posts: 23,576
Likes: 38
From: EXTREME southwest CT
I'm not familiar with "leaking 60 psi up through the valve cover on the drivers side (tdc #1)"
Cylinder #1 is at the front of the passenger side.
That bank is 1-->4 front to back.
The drivers side is #'s 5-->8 front to back.
You have to check each cylinder when *it* is close to tdc on the compression stroke (both valves closed) and give a % (percentage) of leakdown.
If you put 100 regulated psi into cylinder #1 and had a 40 psi reading you have 60% leakdown.
Really, anything leaking to the crankcase should be heard at both valve covers
There are only four options.
Bad cylinders. Rings or pistons leaking into crankcase.
Bad intake valve sealing. Leaking to intake.
Bad exhaust valve sealing. Leaking to exhaust.
Cracked heads or blown head gasket. Leaking into cooling system.
Cylinder #1 is at the front of the passenger side.
That bank is 1-->4 front to back.
The drivers side is #'s 5-->8 front to back.
You have to check each cylinder when *it* is close to tdc on the compression stroke (both valves closed) and give a % (percentage) of leakdown.
If you put 100 regulated psi into cylinder #1 and had a 40 psi reading you have 60% leakdown.
Really, anything leaking to the crankcase should be heard at both valve covers
There are only four options.
Bad cylinders. Rings or pistons leaking into crankcase.
Bad intake valve sealing. Leaking to intake.
Bad exhaust valve sealing. Leaking to exhaust.
Cracked heads or blown head gasket. Leaking into cooling system.
Senior User
Joined: Dec 2010
Posts: 359
Likes: 0
From: Shafer, MN
Re-test the cylinders 1 by 1, this sounds like the issues I was having with my 302, ended up being a hole punched in the #8 piston. Engine runs, to this day runs, but that plug is fouled up, i get oil coming up in places it shouldnt.
Start the engine, take off the oil cap, and tell me if the engine sucks on your hand or pushes it away
Start the engine, take off the oil cap, and tell me if the engine sucks on your hand or pushes it away
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