Robert56

iTrader: (2)

I am having an issue with the oil in the intake, well actually it's in the combustion chamber and working it's way back up into the intake (reversion). I also removed the PCV all together because of oil in the intake big time (could feel and see oil in the TB neck). So after blowing my ls6 intake I put a ls1 on and washed it out realy good to follow the oil issue. Now I took the intake off to put the single plane on and noticed oil around the gaskets between head/intake hmmm... So, I check the intake out and oil is not in the plenum, so this indicates it's coming from the cylinder heads/combustion chamber. I look inside the intake ports and six of the cylinders that had the valves closed had a teaspoon of oil sitting on the closed intake valve. Still haven't figured it out. But feel it must be coming down the valve stems. The heads are stock LS6 with a new valve job. I have also heard of others with a similar issue running the 408 with no PCV, related? Any insight out there?


Here's a quote of another similar issue. Both 408s were built by LME, and I know mine has some loose rings .028 top and .021 second (built for a 300shot). Could oil be coming up past the rings because of the PCV missing and the engine just trying to breath?
Robert

brad8266

iTrader: (23)

Oil sitting on the top would seem to be messed up valve guides and/or valve stem seals. But I suppose it could be from blowby due to the losse rings with no PCV.

bczee

iTrader: (12)

Yeah.. I would vote on the Valve guides seals.. maybe do a Leak down test to see if that can help isolate.

Are you getting any while\blue smoke in the exhaust ?... what do the plugs look like ? (any signs of oil)

Robert56

iTrader: (2)

Yea, you would think the valve seals or guides. However, I can't believe that a new set of rebuilt heads @ 15k original miles, (and a couple hundred miles on them now) would have oil leaking to the point of puddling in all cylinders? The other example is also a 4k brand new motor with differnt heads and oil in all cylinders? It just desn't make sense at this time. I don't have my leak down kit, as i loaned it and never got it back.
Robert

oldmanwinter

Why does it not have a PCV? Does it have full roller rockers? Have you checked the wipe pattern. Could be off and wearing the guides.

wws699

iTrader: (3)

How about the rocker arm studs?? The studs penatrate the intake runner.... I'd pull em out and seal the threads...

SOMbitch

iTrader: (8)

X2^^^^^

Sigforty

I would try that first. I like to use the Permetex thread sealant on the threads of the rocker arm bolts. I placed it about a 1/4 inch from the end of the threads on the bolt. This places the sealant right in the middle of the threads. It is about the easiest and cheapest thing to do to try and solve the problem. If this does not help then I would look at valve stem seals. I seriously doubt you are getting enough blowby to revert that much oil ontop of the valves. I would look at sources of oil from the heads first.

Robert56

iTrader: (2)

Yea I will check to see if it looks like they were sealed. That's one of the few things that is common to all the holes because of having a valve job done. The valve seals are in place and brand new, just a couple hundred miles, so I wouldn't think they would be bad on every hole. It's something that is effecting all of the holes.

Update: I checked the manual and it says nothing about sealing the rocker bolts. Also, I can feel the boss for the intake valve rocker bolt and they do not protrude through the casting. Remember these are bone stock LS6 heads. Is something different on the exhaust rockers, as I still have heads on car with headers and can't see or feel into the comb chamber like I can the intake.

I talked to the shop that put the heads on the motor and installed motor, and they said I may have hurt the rings when I had my nitrous back fire, though I doubt that all the cylinders could be hurt as some of the valves were closed, unless cylinder pressure from below comprimised the sealing ability. I wll be doing a cylinder leak down on that issue.

Robert

wws699

iTrader: (3)

The exhaust side is different as far as placement of the rocker studs, they dont penatrate the casting and are about 1" from the exhaust runner..