Oil Deposits in Intake
#1
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Oil Deposits in Intake
Hi there, I recently purchased a 2002 Trailblazer LTZ 4WD. 4.2L inline six. 177,000 miles on it.
I've been doing some maintenance on it, it was leaking oil from the valve cover so I pulled off the intake manifold (you have to to get to the valve cover) and there is a lot of wet like oily grimy residue in the intake and the heads. What causes this? I haven't pulled the valve cover off yet, may do it tonight.
It was supposedly taken good care of by previous owner. was sitting last 2 years without being driven. but with plugs and coils, O2 sensors, fuel filter, etc. it runs really good.
however, it does have an evap problem. I found a leak and fixed it but still have code for evap leak. don't know if this would have anything to do with it. I plan to drop the tank soon to look into the leak.
Here'* a pic of head. intake was the same. cylinders all look similar. you can scrape this off like mud.
One last thing, I cleaned the intake, but is there a way to clean out the heads?
Thanks for your help!
I've been doing some maintenance on it, it was leaking oil from the valve cover so I pulled off the intake manifold (you have to to get to the valve cover) and there is a lot of wet like oily grimy residue in the intake and the heads. What causes this? I haven't pulled the valve cover off yet, may do it tonight.
It was supposedly taken good care of by previous owner. was sitting last 2 years without being driven. but with plugs and coils, O2 sensors, fuel filter, etc. it runs really good.
however, it does have an evap problem. I found a leak and fixed it but still have code for evap leak. don't know if this would have anything to do with it. I plan to drop the tank soon to look into the leak.
Here'* a pic of head. intake was the same. cylinders all look similar. you can scrape this off like mud.
One last thing, I cleaned the intake, but is there a way to clean out the heads?
Thanks for your help!
#2
Senior Member
More than likely from the PCV.
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TommyB (10-20-2022)
#4
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no PCV on this engine. it has a hose that goes from air cleaner to the valve cover. according to my FSM this supplies fresh to the crankcase. then there is a hose that goes from the lower part of the head to the intake manifold, this lets out crankcase vapors I think. nothings clogged. but could that be why I have the sludge in the intake? I can't imagine this being normal, maybe it is, there aren't any symptoms, car runs good. I just thought that was a lot of gunk.
#5
Senior Member
no PCV on this engine. it has a hose that goes from air cleaner to the valve cover. according to my FSM this supplies fresh to the crankcase. then there is a hose that goes from the lower part of the head to the intake manifold, this lets out crankcase vapors I think. nothings clogged. but could that be why I have the sludge in the intake? I can't imagine this being normal, maybe it is, there aren't any symptoms, car runs good. I just thought that was a lot of gunk.
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carfixer007 (10-20-2022)
#7
Senior Member
True Car Nut
I'd say cleaning the ports out might cause more harm than it solves. Even if you're meticulous with a vacuum some chunks will fall in and might create issues. If you never took it apart you'd never know the difference.
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TommyB (10-23-2022)
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