Last night I pulled the TB and the inside of the intake manifold is covered in oil. It did not come from the fresh air rubber tube either. Is this blowby or something else?

There are random puffs of smoke coming out the tail pipes. Looks more whitish than blue but I am colorblind and I dont think this is a head gasket. Maybe a leaky intake gasket? Pulled the driver valve cover and saw puffs of smoke there too.

Exhaust tips are turning black too. Smells bad too.

Oil filter revealed small (.010") bright silver flakes that appear to be aluminum. Maybe piston???

Yes I know it looks bad.

Thoughts?

 

Don't freak out yet. I have seen times when a TI retainer would be failing (pulling the lock through) and get chewed up and put flakes into the pan. A broken spring will do this to, or if your springs have the flat wire damper they can chew into a TI retainer pretty quickly. Is your oil pressure fine or similar to previous? No abnormal sounds? The puffs of smoke in the valve cover area.. had the engine run for long enough to get the oil good and hot? Were you revving the engine at all?

My intake isn't covered inside with oil but it is sooted up pretty evenly and if I am looking at it with the engine cooling down it will condensate and look like oily residue pretty easily.

If it were me, my next step would be a compression and leakdown check, and possibly oil analysis to determine exactly what was in my oil before I tore it down. I would probably pull both valve covers and inspect the rockers and retainers.

 

Oil pressure seems acceptable except for the funky negative spike of 20# I get at 5.5K RPM. Still have 23# at idle and 40# cruising. The pickup fell off a few weeks ago and was replaced. There was some gold flake in the bottom of the pan but the pressures seemed to remain the same. Not sure if I had the negative spike before that or not.

No abnormal sounds at all. The puffs of smoke occured a few minutes after turning the hot motor and simply removing the valve cover. Nevr seen that before and up till recently the inside of the intake was always sooty black just like what you described.

We are going to do a leak-down test next. I will look at the retainers too.

How is it possible to get oil into the intake like this if it does not go through the fresh line from the TB to the valve cover?

 

Had the engine builder just check the silver particles and they did stick to a magnet. That rules out pistons. The TI will not stick to the magent. I can rule that out.

He is going to look at the old oil pump gears next. Hopefully its not crank journal surface.

 

It comes in through the PCV valve and system, which "dumps" those "re-cycled" crankcase fumes right back into the intake manifold just behind where your throttle body mounts.

 

It only happens that way when there is excessive blowby, and inadequate flow through the PCV valve. When that happens, the air SUPPLY line, turns into a pressure relief line, and flows backwards into the TB, picking up oil droplets as it passes through the valve cover.

 

There is no way it came through the fresh air line. It was dry plus I have a filter on it. Also there was no oil in the TB. This came from elswhere I hope as a result of the oil being overfilled to diagnose the pressure drop issue. I cleaned the intake out and I need to drive it some to see if the problem remains.

 

Do you still have the sheet metal "pan" on the bottom of the intake manifold?

 

Yes.
I will get to drive it some today to see if the problem is any better.

I am not convinced I have blowby yet. I can pull the filler cap off and feel or hear nothing abnormal. I am planning on doing a leak down soon.

 

Why not start with a crankcase manometer to check the level of vacuum?

I think the metal came from the oil pump drive gear. A lot of people have a problem between the cam and oil pump gear being incompatible. Thus the issues with oil pressure as the gear is failing. Ask your engine builder what type of gear was on the cam. You should have pulled it while you had the intake off.

 

I did pull the pump drive stub out while I had the intake off for inspection. The teeth were very well intact with little wear. The wear marks were a bit more rough in appearance than what I would have expected. I would have expected smooth shiny wear marks. Dont know if that means anything but the drive gear is doing its job.

The gear on the cam was spec'd by Lloyd and I will assume its correct.

We are going to check the old pump gears flow gears for wear and to see if the chips came from there. The chips are attracted by a magnet so I can rule out pistons, titanium retainers.

 

Injuneer, first off, what you have described above does indeed occurr when there is EXCESSIVE crankcase pressure .... the air "supply" line from the passenger side valve cover does act like a "pressure relief valve", and can deliver EXCESS crankcase oil fume back through the throttle body and into the intake manifold. This scenario was, however, NOT what I was referring to in my post above.

To better understand this, one needs to know how our PCV valves work under NORMAL operating conditions. Since I cannot post a photo of the actual passage I'll be citing here ... I'll cite the reference itself. If you can, please refer to: "Modern Automotive Technology" by James E. Duffy, Chapter 43 Emission Control Systems, Page 793.

I quote .... "At idle, the PCV valve is pulled toward the intake manifold by HIGH vacuum. This RESTRICTS the flow of air and prevents a lean air-fuel mixture. When cruising, LOWER intake manifold vacuum allows the spring to open the PCV valve. However, enough vacuum is present to keep the PCV valve from completely closing. MORE air can now flow through the system to clean out crankcase fumes. At wide open throttle or with the engine off (low or no intake manifold vacuum), spring pressure closes the PCV valve COMPLETELY".

Now, once you understand the above cited passage that explains how PCV valves are calibrated to deliver MAXIMUM flow at INTERMEDIATE vacuum levels ..... you should be able to follow the following "phenomological" explanation of how crankcase oil fumes still manage to coat the inside of CAMMED LT1 engine intake manifolds .... even with that valve cover to throttle body "fresh air" tube ..... TOTALLY disconnected.

When our stock LT1 cars left the St. Threse assembly plant .... "The General" (i.e. GM) had designed a PCV valve and system to work "in harmony" with the 17 to 18 inches of "normal" idle intake manifold vacuum these cars then produced. Hence, the OEM PCV valve, (and all other parts store replacement PCV valves for that matter), have internal springs calibrated to produce MAXIMUM flow at about 9 to 11 inches of manifold vacuum. That is, during "cruising" (see cited reference above!), when actual airflow through the intake manifold is moderate, and hence better able to "dispense" re-cycled crankcase fume.

When we put higher "performance" camshafts in our "modified" LT1's .... we then drop the IDLE intake manifold vacuum to the 9 to 11 inch range, which, at idle speed, does NOT have enough airflow through the intake to adquately disperse NORMAL crankcase fume. Not to be-labor the point, but what I am saying here is that during NORMAL PCV operation .... in a CAMMED engine ...... the "stock" PCV valve calibration allows for MAXIMUM crankcase return flow during a period (i.e. at idle speed), of very LOW actual airflow through the intake manifold. This condition oftens manifests itself as "oil in my intake manifold", even when the "fresh air" tube is dis-connected, because, again, PCV flow is maximized during minimum intake airflow.

Hope this additional info clarifies my original answer, and explains to the OP why he is STILL getting oil in his intake, even with that "air supply" line either filtered or dis-connected???

 

Wrd1972, remove your BBK 58mm throttle body and shine a pen/flash light directly down into those, (now exposed), twin 58mm holes, in the very FRONT of your intake manifold. Approximately 1/2 inch back from the throttle body mounting surface, in the "floor" of your intake manifold you will see two(2) 1/2 inch diameter holes, one(1) on each side of the intake manifold floor "hump". These "return holes" are where your properly functioning PCV system will return NORMAL crankcase vapor into your intake manifold for re-combustion through your engine.

Is there a build-up of oil DIRECTLY around these holes??? If so, the ONLY place that's coming from is from your PCV system. If the oil is more uniformly distributed all around your intake manifold, you have other problems.

 

I don't think he was describing "oil fumes". I think its heavy, raw, wet oil. The pan on the bottom of the intake manifold should provide a "stilling" volume to prevent the high flow of crankcase vapor into the PCV port from pulling in entrained oil droplets.

I've opened up high performance LT1's, running the stock PCV system, and haven't found raw, wet oil building up the manifold. "Dark" on the walls.... yes, but not the condition described by the OP.

 

Right now the intake has been thoroughly degreased. I will have to do some driving then do this check.