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Old 11-14-2015, 06:36 PM
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1996 L31 Vortec - Brown & Black heads? - Pics

Hi guys, we are upgrading a '96 Yukon, we pulled the heads yesterday
but before that, we found something i think it's weird and i've never
seen before this condition.

Driver's side head & components were black.
Passenger side head & components were brown.

Truck ran pretty good but there was a constant exhaust backfire
from quite sometime and we replaced all ignition & spider injector
for upgrades and that did not cure the problem.

Looking at this thing makes me thing it was gasket related
since the intake gaskets were really ugly.

What you think?
Thanks!



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Old 11-15-2015, 05:02 AM
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The black side is running hotter causing more oil 'sludge' build up. Next question - why is that? I don't know, but my guess would be a cooling issue causing that side of the motor to be running hotter.
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Old 11-15-2015, 05:52 AM
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Thanks for the reply, i was told some possibilities
1 - Oil passages clogging
2 - Running true dual exhaust, i will need to add "H" Pipe.
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Old 11-15-2015, 06:25 AM
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Quote:
Originally Posted by Calderone View Post
Thanks for the reply, i was told some possibilities
1 - Oil passages clogging
2 - Running true dual exhaust, i will need to add "H" Pipe.
#1 maybe, but #2 I wouldn't believe. Adding a crossover between duel exhaust is helping performance, but I can't see how not having one could be eading to what you have in your pictures, unless one side is WAAY more restrictive than the other to the point that the exhaust is building enough back preeesure to hold heat in the head.
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Old 11-15-2015, 06:27 AM
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True, anyway we are swapping heads & cam (lifters & rockers too) but i've never seen this brown/black condition on any sbc before.
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Old 11-15-2015, 09:14 PM
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I'd guess that the brown side is all replacement pieces, while the black side is original to the engine....brown rockers look newer.

Black side just looks like typical owner neglect on correct oil change intervals and/or use of Pennzoil.
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Old 11-15-2015, 09:17 PM
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Nope, the brown side was weird because all the pushrods
where half brown, the lower half (which goes into the lifters)
were black but the upper area which goes from the head to the rockers
is brown, i still think its weird, same thing with the valve springs.
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Old 11-15-2015, 09:19 PM
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Maybe it sat with one valvecover off for a few weeks or months in a humid area??
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Old 11-15-2015, 09:19 PM
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No, we just pulled the valve covers two days ago, it was
a running engine.
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Old 11-15-2015, 09:47 PM
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PCV valve was on the black side right?

Fresh air intake on the other right?

Now you know.
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Old 11-15-2015, 09:48 PM
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PCV Valve on the black side, yes, is it needed or should i do better with breathers?
i won't do two breathers ---> https://www.hotrodders.com/forum/pcv-...er-130477.html
the brown side has a tube that goes into the air filter
Thanks

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Old 11-15-2015, 09:51 PM
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Quote:
Originally Posted by 4 Jaw Chuck View Post
PCV valve was on the black side right?

Fresh air intake on the other right?

Now you know.
You've seen this before? And related to the PCV?

Edit - if yes and yes then that doesn't make sense (I think). Please explain.
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Old 11-16-2015, 09:24 AM
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Take a good look @ the distributor,or,just go ahead & replace it.They are notorious for excessive wear,which cause low oil flow to the driver side head.If oil was changed as it should be,I wouldn't think using Pennzoil would have caused it.I've used Pennzoil in every engine I've had for the last 25 years,except for my 6.2 diesel, with no problems at all.
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Old 11-16-2015, 10:49 AM
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Joker, it has a brand new distributor, what was worrying me was the exhaust backfires that wouldn't solve
with new ignition components including crank sensor, but we didn't tear it apart because of this problem,
it's a cam & heads swap. Thanks
ps : still need to remove the damper and check the timing chain but we have a new one to replace the
stocker as well.
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Old 11-16-2015, 03:00 PM
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Quote:
Originally Posted by 64nailhead View Post
You've seen this before? And related to the PCV?

Edit - if yes and yes then that doesn't make sense (I think). Please explain.
Yes and yes.

Only seen it on engines from down south where it never snows, first time I seen it was on a Honda V6 from Arizona.

Fresh cool air in one side, dirty hot gases out the other side where it deposits. Pretty simple when you think of it.
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