Suggestions RE: Oil Fouled Plugs - The 1947 - Present Chevrolet & GMC Truck Message Board Network

John Pasinski · 09-28-2011, 03:27 AM

I have a '72 402BB. On the passenger side bank the plugs continue to foul out & build up with what appears to be more like oil than carbon. The first plug (front) isn't too bad, but they get worse till the rear plugs are really caked up. I do have "colder" plugs to install, but if the left bank is fine, I don't think installing a colder range plug will remedy this. I think its a more serious issue. My question is; how do I determine if it's valves, valve seals, or rings?

heeroyue2002 · 09-28-2011, 04:28 AM

i used non foulers for a bit.

Autoblueprint · 09-28-2011, 06:46 AM

Quote:

Originally Posted by John Pasinski

My question is; how do I determine if it's valves, valve seals, or rings?

You can do a cylinder leakage test ( the tool is available at Summit Racing # SUM-900010 $72.95 ) but in all probability it is the valve seals that are oil fouling your plugs, which is a common problem on high mileage engines.

The valve seals are an easy enough fix as their replacement can be done with the heads on if you have an air compressor that puts out 150 PSI and have a air hold ( WMR-W84003 $9.95 ) and head-on valve spring compressor ( SUM-906784 $44.95 ). These are Summit Racing part numbers / prices.

bobs409 · 09-28-2011, 06:58 AM

Could also be the intake gasket is allowing oil to be sucked in from the lifter galley into the intake ports.

JimKshortstep4x4 · 09-28-2011, 07:37 AM

As mentioned it is probaly valve seals but make sure the drains in the heads are not plugged causing a ponding of oil in the valve cover.

Jim

John Pasinski · 09-28-2011, 04:32 PM

My apoligies guys. I neglected to mention I overhauled it about 4000 miles ago. So I don't think it's the valve seals or plugged oil returns.
I'm waiting for a borrowed compression tester to get here. I want to see if the cylinders are close to a "normal" reading. It's only (at this point) the left bank (passenger side). And the fouling gets worse from front to back.

Wrenchbender Ret · 09-28-2011, 06:16 PM

If its an auto trans. Check the modulator. It can suck iol out of the trans. The vacuum usually feeds off the rear port in the intake.

09-28-2011, 03:27 AM	#1
John Pasinski Registered User Join Date: Aug 2007 Location: orlando Posts: 456	Suggestions RE: Oil Fouled Plugs I have a '72 402BB. On the passenger side bank the plugs continue to foul out & build up with what appears to be more like oil than carbon. The first plug (front) isn't too bad, but they get worse till the rear plugs are really caked up. I do have "colder" plugs to install, but if the left bank is fine, I don't think installing a colder range plug will remedy this. I think its a more serious issue. My question is; how do I determine if it's valves, valve seals, or rings? __________________ A man's thoughts devise his ways; but it's GOD that directs his steps.

09-28-2011, 04:28 AM	#2
heeroyue2002 fat old dude Join Date: Feb 2010 Location: fresno, california Posts: 1,424	Re: Suggestions RE: Oil Fouled Plugs i used non foulers for a bit. __________________ 1972 c-10 shortbed 350/400 build thread http://67-72chevytrucks.com/vboard/s...d.php?t=389157 1968 workhorse http://67-72chevytrucks.com/vboard/s...d.php?t=446216 Accepting part donations

09-28-2011, 06:58 AM	#4
bobs409 1969 Custom 30 wrecker Join Date: Sep 2001 Location: Pottsville, Pa Posts: 2,611	Re: Suggestions RE: Oil Fouled Plugs Could also be the intake gasket is allowing oil to be sucked in from the lifter galley into the intake ports. __________________ Bob 63 Impala 283/PG/3.36 (under restoration) 66 Impala 327/PG/3.36 66 Chevelle SS 409/M22/3.55 69 Chevelle 307/PG/3.08 (future restoration) 69 C10 short stepside 454/TH350/3.73 69 Custom 30 tow truck 350/4 spd/4.10 (resto done, CRUISIN TIME!) 71 Cheyenne 20 fleetside 350/4 spd/4.10 71 Chevelle 6/PG/3.08 72 Chevelle 454/M21/4.10

09-28-2011, 07:37 AM	#5
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Re: Suggestions RE: Oil Fouled Plugs As mentioned it is probaly valve seals but make sure the drains in the heads are not plugged causing a ponding of oil in the valve cover. Jim __________________ 1971 Shortbox step side 4x4, 350 sbc, 3:07 rear end 1965 Impala SS 400 sbc, Muncie rock crusher 1966 Impala SS 396 bbc, TH 400 1969 El Camino, 350 sbc, TH 350 1971 Snowplow built on a Blazer frame 1972 GMC Short bed, stepside, TH 400, 427 BBC

09-28-2011, 04:32 PM	#6
John Pasinski Registered User Join Date: Aug 2007 Location: orlando Posts: 456	Re: Suggestions RE: Oil Fouled Plugs My apoligies guys. I neglected to mention I overhauled it about 4000 miles ago. So I don't think it's the valve seals or plugged oil returns. I'm waiting for a borrowed compression tester to get here. I want to see if the cylinders are close to a "normal" reading. It's only (at this point) the left bank (passenger side). And the fouling gets worse from front to back. __________________ A man's thoughts devise his ways; but it's GOD that directs his steps.

09-28-2011, 06:16 PM	#7
Wrenchbender Ret Registered User Join Date: Oct 2005 Location: Overland Park, Ks. Posts: 5,228	Re: Suggestions RE: Oil Fouled Plugs If its an auto trans. Check the modulator. It can suck iol out of the trans. The vacuum usually feeds off the rear port in the intake.



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