Chevy 350 Blown HG at oil galley?

[acoen]

Hey guys I just purchased a truck from my buddy. A 1989 Chevy Silverado 4x4 stepside w/350. Nice truck. He just had the headgaskets replaced. Well recently he noticed it running rough and thought that he had a weak #5 cylinder because that one plug was oil fouled. I purchased the truck tuned it up, changed the plugs and it runs pretty good, but today it acted like the starter was dragging...Rara...ra...ra. Then it starts and a cloud of blue white smoke filled my street. The smoke settles down but increased dramatically on accelleration. Pulled the plug and it is completely covered in oil. Crankcase oil looks good but dark. I think I blew a headgasket at the oil galley. Is that possible? Truck runs pretty smooth and has power just smokes like the mosquito guy...

I'm going to give her a comp test tomorrow. I think what is happening is when the engine is at idle not much oil if any is getting in but once the RPMs come up the cylinder is sucking in oil from the return galley. Has anyone seen this before?

 

[Junior Samples]

lets hope its only leaking past the valves and not a ring

put vacuum gauge on it first and isolate it, then do a leak down if you have the good comp tester. the vac gauge will point ya in the right direction and the comp tester will confirm.

i dont think its a head gasket, hard to blow head gasket on stock sbc unless you overheated

find out anyway and if heads i can set you up with a pair if needed and not 1000000 miles away

 

[Chuck Leeper]

Intake gasket...

 

[tony moore]

is this the same problem he was having when he replaced the head gasket? sounds like a broke ring or busted piston to me. i would do as suggested above and try a leak down/compression test. hth

 

[acoen]

Played with it this morning. Did a compression test. On the number 7 cylinder,120 psi and holding with oil around 130-135. The others are around 130ish. The engine runs smooth. slight smoke at warm idle.....little to none cold. Smokes like a frieght train warm, once rpms are above 1500-2500. With the engine running as smooth as it does, I'm leaning towards valve seal. I pulled the spark plug today just after running in the driveway today and the plug is saturated with oil. I have a hard time believing it lost a ring with the above stated compression. Compression held pretty good at 120, bled down to 90 in about 4 or 5 minutes (but there is oil in that cylinder from running). Weird problem.

Thanks guys....

 

[Junior Samples]

yup umbrellas, guides pretty much what i thought but i think i posted before i had a pot of wake the F up coffee

 

[acoen]

Really the only thing I can think of. At first I thought maybe a HG but the symtoms aren't there. The truck runs good, I mean really good! If it was a broken piston or ring will make the engine run like crap. The first time I did a comp test on #7 it ran up to 125 psi and leaked down to 95 or 100 but it could have been the valve on my gauge leaking down. The truck runs very smooth.....

Yesterday I had the damn thing smogged and it passed perfectly. I changed the oil about 3 days ago and it still appeared low on the stick so on my way home from the smog shop, I added a bottle of STP then drove it a block and a half home and parked it. I washed down my motor and the truck. Then I went to start it and the engine slugged...I thought no big deal, must be the starter dragging....Then the flipping smoke after it warmed up. I think when I added the STP it drained back to the number 7 cylinder. I bet some oil drained into the cylinder (through the valve guide or seal) causing the engine to slug blowing the valve seal off. Only thing I can think of. For an engine to smoke like it does and run so good it is the only thing I can think of....

Any other thoughts....Never seen this before.

 

[Junior Samples]

if i remember, if its your umbrellas you will get that puff when you first start then it goes away, if its your guides it will start giving off the smoke screen as the oil pumps into valve train.
A wet and dry compression test can point you in the right direction. First the compression is tested and the results noted. This is the "dry" portion of the test. Then a couple of squirts of oil into the cylinders and the compression test taken again. This is the "wet" portion of the test. The oil will temporarily seal the rings to the cylinder wall. By comparing the dry and wet readings, it can be determined if the rings are bad or the valves. If the wet readings are about 20% higher than the dry readings, you have weak rings. If the readings are basically the same, then it's the valve seals. <---i just copy/pasted from some dummy ask a mechanic website

im certainly no good at keyboard diagnostics..if its in front of me i can troubleshoot but if i have to use my brain for something like how to change a tire then forget it..lol

 

[tony moore]

as stated above,you need to do a dry test. not to wish you any bad luck but the way you are describing it i don't think it's seals.

 

[acoen]

I just took 10 minutes and did a dry test....so to speak. Oil has fouled the one plug in question. The reading I received was 130 psi...I'm sure it would be more if I were to remove all of the plugs. I squirted one spuirt of oil into the cylinder and I got about 135 psi. Looks like I need to look at the valve seal. What sucks is that there is oil in the cylinder all ready but I did it cold, engine sitting for about 4 hours. I hope we have it narrowed down. Thanks guys. I have a compressor and a valve spring compression tool. I need two valve seals and air hose adapter and 2 hours..I should have it. Hard to believe it runs as good as it does. A perfect idle, blue smoke and all.

Aaron

 

[tony moore]

the end of your compression tester makes a great air hose for the cyl. i have some of the o ring style valve seals. hope that fix's it!

 

[acoen]

the end of your compression tester makes a great air hose for the cyl. i have some of the o ring style valve seals. hope that fix's it!

Now that's a great idea, I may have the fittings to adapt the gauge side to the compressor side. Dumb question, how do you perform a leak down test?

 

[acoen]

Thanks again guys, this one just stumped me....Damn Chevy's! I love this site, help from every direction. Funny that I can chase down problems on my GN but it take a 350 chevy to stump me....Happy New Year. I will keep you posted on my findings.

 

[Junior Samples]

Yeah funny how 6 months back chevys was all i knew and now that ive been on here devouring every thread, ive almost forgot my 20+ years of smallblocks..lol

Air leakage Table:
Leaking out the exhaust = Exhaust Valve
Leaking into the intake = Intake Valve
Air bubbles in the top of the radiator(take off the rad cap) or into the adjacent cylinder = headgasket
Oil cap, Dipstick, Bottem end = Piston Rings

and here is a site with the basics...i did like guy on site and welded a milton on old sparkplug

LEAKDOWN TESTING BASICS By Michael Meyer

 

[Chuck Leeper]

Intake gasket..
Why would just 1 stem seal wear out???

 

[tony moore]

chuck you probly know this but the stock seals were just o rings so it could have broke. but as i said before i don't think that what it is.

 

[acoen]

Yeah funny how 6 months back chevys was all i knew and now that ive been on here devouring every thread, ive almost forgot my 20+ years of smallblocks..lol

Air leakage Table:
Leaking out the exhaust = Exhaust Valve
Leaking into the intake = Intake Valve
Air bubbles in the top of the radiator(take off the rad cap) or into the adjacent cylinder = headgasket
Oil cap, Dipstick, Bottem end = Piston Rings

and here is a site with the basics...i did like guy on site and welded a milton on old sparkplug

LEAKDOWN TESTING BASICS By Michael Meyer

Yep, I can diagnos a TR in my sleep. The above makes since to me as well. When my 69 camaro broke a piston years ago, I recall now blowby coming from the crankcase out through the valve cover breather...I have non of that at all.

 

[Junior Samples]

i just dont think a leaking intake gasket although on #7 cylinder would pull that much oil from the valley if its smokin like a james bond mobile, i try to picture oil weaping up and along you take the angle in which the intake sits on the head, crankcase is vented so its not going to pull oil up to underside of intake gasket into port to be burnt.

But then I see who it is aka Chuck L and having read his posts on other threads and knowing who he is etc i start to second guess myself cause it really doesnt matter how much i know, i think other guys in here have forgotten more then i'll ever learn

All i know is a vacuum gauge will point one in the right direction everytime and if the intake has any leak then the gauge will show, and valves and rings on and on

clogged pcv will cause crankcase to volcano out as well

 

[Junior Samples]

and he's right..why would just one seal go bad? was there head work done and they only did one chamber as in #7? valves, guide etc

 

[acoen]

Intake gasket..
Why would just 1 stem seal wear out???

The heads were done recently and the mechanic wasn't the best (the previous owner's uncle or something) I don't have faith in the fact that he didn't do everthing right. He wire tied all of the plug wires together, then diagonsed a miss as a weak cyliner. I inspected the wires and found one bad wire, repaired it and it idles nearly perfect. I just purchased the truck about 2 weeks ago, the oil that came out of the truck was as thick as honey. I think this was what the mechanic was trying to do to fix the problem.

Chuck....You may have some good imput as well. Why would you lean on the intake being the problem? You may be on to something here and I'm learning, I haven't seen before, without the engine running horribly. Valve stem seal seems to my best choice but you may know something I don't....