engine diagnostic after comp test - The 1947 - Present Chevrolet & GMC Truck Message Board Network

mole2000 · 04-20-2009, 08:39 PM

My 454 recently started losing oil out the #6 cylinder (3rd back on pass side). It was heavy enough that oil started showing up around the header pipe. At idle, at first start, not a lot of smoke. After it's warmed up, a noticeable amount of smoke comes from that banks exhaust outlet, but not heavy at all. If I take it on the highway it really makes a lot of smoke, but not at high revs in the driveway standing still. So I figured I would do a compression test which would at least give me some more info.

All cylinders were between 110 and 120, which I don't think is that good, but at least they're consistent. A wet test in the #6 cylinder made no difference in the result. I pulled the valve cover and at first glance everything looks normal.

Any ideas on where I should look next? I was happy with performance prior to the oil leak- and it still runs okay other than the oil loss mess and smoke.

Thanks.

mole2000 · 04-21-2009, 11:23 PM

i solved this by replacing the valve stem seal on the exhaust valve of the cylinder in question. it was completely split vertically on one side, partially on another and still one more crack horizontally. it was literally falling apart. i plan on doing the rest soon.

72blue · 04-21-2009, 11:44 PM

glad u found it. that was going to be my suggestion
James

QKENUF4U · 04-22-2009, 12:17 AM

geezzz 110psi and your happy with the performance ??????? ya i figured same thing with valve seals. glad it was a semi-easy fix...... now ya need to pull it down and redo the rings/pistons and hold on tight.....lol

mole2000 · 04-22-2009, 08:54 PM

yeah, I dont get on it too much- basically cruising. Since getting it rolling- I had to rebuild front end, added power steering and brakes, rewired a bunch of stuff- this was the first time I had really taken it out at highway speeds. I'm not sure the transmission if being very effective at moving the power through the drivetrain... That may be my next move before an engine rebuild...

The 110-120 is in the middle of the green/red change on my gauge, so I was not overly enthusiastic, but at least they were all pretty consistent. I am currently researching machine shops in the area and no longer spewing oil out. So at least I'm still rolling!

Thanks guys!

04-20-2009, 08:39 PM	#1
mole2000 Registered User Join Date: Aug 2008 Location: Austin, Texas Posts: 78	engine diagnostic after comp test My 454 recently started losing oil out the #6 cylinder (3rd back on pass side). It was heavy enough that oil started showing up around the header pipe. At idle, at first start, not a lot of smoke. After it's warmed up, a noticeable amount of smoke comes from that banks exhaust outlet, but not heavy at all. If I take it on the highway it really makes a lot of smoke, but not at high revs in the driveway standing still. So I figured I would do a compression test which would at least give me some more info. All cylinders were between 110 and 120, which I don't think is that good, but at least they're consistent. A wet test in the #6 cylinder made no difference in the result. I pulled the valve cover and at first glance everything looks normal. Any ideas on where I should look next? I was happy with performance prior to the oil leak- and it still runs okay other than the oil loss mess and smoke. Thanks.

04-21-2009, 11:23 PM	#2
mole2000 Registered User Join Date: Aug 2008 Location: Austin, Texas Posts: 78	Re: engine diagnostic after comp test i solved this by replacing the valve stem seal on the exhaust valve of the cylinder in question. it was completely split vertically on one side, partially on another and still one more crack horizontally. it was literally falling apart. i plan on doing the rest soon.

04-21-2009, 11:44 PM	#3
72blue Registered User Join Date: Feb 2009 Location: arroyo grande, ca Posts: 206	Re: engine diagnostic after comp test glad u found it. that was going to be my suggestion James __________________ James

04-22-2009, 12:17 AM	#4
QKENUF4U Senior Member Join Date: Jan 2005 Location: SUNNY WARM BIKE RIDING COTTONWOOD ARIZONA Posts: 2,097	Re: engine diagnostic after comp test geezzz 110psi and your happy with the performance ??????? ya i figured same thing with valve seals. glad it was a semi-easy fix...... now ya need to pull it down and redo the rings/pistons and hold on tight.....lol

04-22-2009, 08:54 PM	#5
mole2000 Registered User Join Date: Aug 2008 Location: Austin, Texas Posts: 78	Re: engine diagnostic after comp test yeah, I dont get on it too much- basically cruising. Since getting it rolling- I had to rebuild front end, added power steering and brakes, rewired a bunch of stuff- this was the first time I had really taken it out at highway speeds. I'm not sure the transmission if being very effective at moving the power through the drivetrain... That may be my next move before an engine rebuild... The 110-120 is in the middle of the green/red change on my gauge, so I was not overly enthusiastic, but at least they were all pretty consistent. I am currently researching machine shops in the area and no longer spewing oil out. So at least I'm still rolling! Thanks guys!



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