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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: pholliday1 on October 24, 2013, 10:10:31 AM
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I'm assuming blown head gasket? If in fact there is a block issue is there a common place they crack? Purchased truck in this condition changed oil and filter, immediately oil becomes contaminated. Are these blocks known for head gasket problems? I have zero history from PO on this truck 1987 Chevy K30 4x4. Looking for suggestions.
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dont know much about bbs' but intake gasket could also cause this. i think if you have the antifreeze tested for exhaust gasses then this would tell you where it was from. if no gasses then i would assume it was from the intake
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The front clip is off from this and the engine is easily accessible so this thing is going to get a top end tear down and then ill know.
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You typically don't see head gasket problems on bbc's but it can occur.
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If there's no evidence of compression loss you might want to look into popping the intake off first as suggested.
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Do you have an aftermarket aluminum intake? BBC are susceptable to sucking intake gaskets with aluminum intake manifolds, but you generally only see it on high load applications (i.e. a truck hauling or pulling a load).
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Bone stock no frills trucked was rolled at some point years ago, truck was brought back to the farm the roof was cut off ( proud farmer fashion) and used as farm truck/tractor. Later box was sold cab and clip parted out. I ended up with essentially a carcass, with all the saved computer, steering, and wiring harness. I fashioned a firewall out of 3/4 plywood and bracing made a little shelf for the computer, wired everything up mounted a radiator changed the oil( which was contaminated) Changed the oil and it ran horrible and oil was recontaminated . The motor really needs to be torn down, its been sitting for a couple years and the crank bearing aren't a big fan of anti-freeze so I can only imagine what they look like. In the end I didn't pay a lot for this and I'm gonna start by pulling the heads and see what I find..
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In addition to obvious top end leaks, check for cracks low in the cylinders.
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Only had enough time to pull intake last night. Engine is original to truck, numbers on front right of block matches frame number. Number 8 rocker was side ways and push rod is bent. The intake gasket shows signs of possible leak. Should have time to pulls heads tonight, will report my findings. Also the inside of the motor looks fairly clean is there anyway to tell/judge/guess approx. mileage of motors by looking at the internals?
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You can measure the swept portion of the bores with a bore gauge and calibers and compare to stock bore spec. Normal in my experience is about .001" per 5000 miles, but it depends a lot on service history and oil used.
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Okay the mystery deepens...... I pulled the heads with gaskets still in good shape and no obvious problems. Forgot to mention also found exhaust manifold with several cracks. One mistake on my part was after the third oil change I neglected to check the condition of the oil after I ran the motor again. I think I was so disappointed on how bad the motor was running I just assumed it was a head problem. So after not finding any problems with the heads I pulled the filter and oil and to my surprise almost no contamination. With No info from prior owner I'm leaning toward what I was calling antifreeze in the oil might just be actual water and with the bent push rod on #8 might be that this motor sucked water?? Any theorists out there?
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Could be a bad intake gasket.