For anybody who has been following my oil consumption problems, here is an update and a cry out for help.

The history of my leaks can be found at:
Oil in the intake: http://forums.corvetteforum.com/zerothread?id=305955
Bad fitting manifold gasket: http://forums.corvetteforum.com/zerothread?id=305955

So far, I have removed my PCV setup and am using 2 K&N breathers. I also replaced my manifold gasket with a Mr Gasket one for which I used RTV on both sides of the gasket. I did not use enough RTV on the back of the block and had a serious leak there. I pulled the intake again and it looked like the ports were all sealed up. I also had run some oil dye in the motor and there was no "glowing" trace into the manifold ports, so I'm sure the gasket/RTV was doing it's job. I replaced the gasket with a Fel-Pro one, again putting RTV on both sides of the gasket. Well, I'm burning (+ a minor leak) 1 qt for every 600 miles. I did not get a real measure of the consumption with the original gasket, but I think it was about 1qt/400 mi (1qt every other fill up). When I put my black light up to my manifold now, I see the "glowing" again and still see some oil in the manifold, although it is not as bad as it was originally. The entire inside of the manifold "glows", which kinda suprises me. My guess is that the air/oil is swirling all over the place inside the manifold.

I'm not sure what I should try next.

More details:
Heads: AFR 195 w/ new Comp Cams teflon seals
Manifold: Weiand Team G Street Ram (#7525)

I also see NO smoke, but I'm clearly burning the oil as all of my plugs are oil fouled. #1 and #2 are not too bad and the plugs are fouled worse as you go toward the back of the motor (ie #7 & #8 are the worse).

Bringing my car into a shop is not an option for several reasons, but mostly money.

I also understand that RTV is not supposed to be used where it may come in contact with gas, but I called the Permatex tech support and they said that it should be fine.

 

Are you sure that 1) Your rings are okay 2) That its not your valve stem seals?

 

I'll try to help, but may need some info.

If you are using original type intake gaskets and have an alum manifold stop doing this. Use a paper (Mr. Gasket) type gasket, seal both sides with RTV and use RTV sealant on the intake bolt threads. Use RTV on fwd and aft sides of intake manifold, not the rubber seals that come in the kits. If your engine is the later style (without the rear draft tube), you must use a PCV valve. Without it your engine will produce too much crank pressure and oil will push thru your seals/gaskets. Two oil breathers may not be enough here. You will get smoke and oil blowing up into the breathers and unless they are at least 6"+ tall they will leak also. It doesn't smell too good coming into the cab of your car either. A PCV in one valve cover and an open breather in the other is what you want. Are your breathers smoking badly? If so your rings may not have sealed properly.

 

First: Replace the PCV system, like the prev poster said. Oil consumption will be higher without it.

Next, I think an important key here is that you said the fouling is worse towards the rear of the engine. I can think of a few possibilities:

1: Rocker studs not sealed. Most aftermarket heads run the rocker stud holes into intake ports. Unless the stud is sealed with RTV you will leak oil straight into the intake port. More oil pools up to the rear as the engine is tilted, so fouling is worse there.

2: Bad valve seals. Just becuae they're new and teflon doesn't mean they're good.

3: High volume oil pump paired with inadequate drain back. Oil pools up on the heads. Once the oil level goes above the valve seals they will leak (no matter how good the seals are). Again, this would be worse towards the rear of the engine.

 

did you re-torque the intake after it cooled off? :confused:

 

Here is my reply in order that I received a response:

Chuck, No, I'm not absolutely certain that it is not from the rings or valve seals, but I really doubt that if it were the rings I'd see oil in the manifold so I'm discounting the rings for the time being.

Dave, I'm running a Fel-Pro 1205 gasket. I'm also not convinced that running 2 breathers (3" diameter by 2" high) could cause 1qt/600 mi. When/if I get my consumption down to at least 1qt/1k mi, I plan on putting the PCV back.

Marcus, the rocker stud info has really perked my interest. I bought these heads used and the rocker studs were already installed. I know the guy had the heads cleaned and it is very possible that no selant was used. Also, I do have a hi vol oil pump (bought it a while ago with the perception that I needed it because I have a solid roller cam). I'll look into this option after I seal the rocker studs. I've also not counted out bad valve seals, but I can't imagine that all of them are bad as the plugs would tell.

drives61, yes the manifold was re-torqued (actually, it didn't need any re-torquing).

Great info, keep it coming.

 

Chris, I experienced similar oil problem, including oil in intake, tried running without PCV etc, just as you have. I learned that just because something was rebuilt or replaced doesn't mean it was done right. In my case, the new valve seals were faulty. Problem now solved. Running without PCV is definitely not a good idea for the reasons others have mentioned.

Make sure your valve cover has the proper "baffle" or else the PCV will suck oil into your intake and you will definitely have a consumption problem. I would also not discount blow by from the rings.

You might want to do compression and leak down test to help you nail down the cause.

Hope some of this is helpful and you find the cause!!

:cheers:

 

Update,

I pulled the pass valve cover and the rocker studs. They didn't have much (if any) type of sealant on them, but it also looked like they were all "blind". In fact, most of them had a little bit of oil pooled up at the bottom. I ran out of time this morning so I couldn't do the driver's side.

I'm now going to persue the hi vol oil pump. I still have my oil pump from the old engine, but I have no clue if it is std vol or if the pickup (which is tack welded on) will work with my pan. I'll keep it updated.

 

Just went out for a cruise and ran the car in neutral at 2000 - 3000 RPMs looking into the oil fill hole. There was some oil pooled in the lower area at the #7 springs, but I believe it is due to the location of the oil drain holes. It was no different at 3000 RPM than at 750 RPM.

I did think that the drain back holes looked pretty small, but I now think they are sufficient since it is no different at 3000 RPM than at idle.

 

chris
i'm not convinced the intake is sealing, as you said oil is in the manifold.
Jegs sells GASGACINCH a sealer for intakes made by Edelbrock. i would try that, as RTV will dissolve in contact with gas even tho the tech guy said it won't, it will.

the fact thatthe intake did not retorque, is a bad sign, as the gasket always compresses some with heating and cooling, unless something is wrong,...


this has nothing to do with the oil pump :cheers:

 

I pulled the intake this weekend. I also have a dye in the oil which glows when viewed with a black light. There was absolutely NO oil getting into the intake from the head to intake gasket.

Now, I'll replace the valve seals. I'll have to order them and a valve spring compressor, and I'm not really sure when I'll get some time again to do it, but I'll post an update once I've done it.

 

Chris, you did mention buying the head used....and you have oil in the intake passages, but not in the intake manifold....so you are clean uphill, but dirty in the heads??? if I read that correctly,...you have a set of heads that have been milled...slightly off, angle milling??? whatever that term is...it changes the head slightly on that gasket mating surface and if the head is milled for compression quite frequently they mill more off the intake side than the exhause side....so that angle changes, opens upat bottom of intake manifold....
I know, I traced a problem like that some time ago...gave me fits, as the gaskets looked compressed and all should have been fine...no sealent worked...finally has 20 mills taken off the TOP of the intake manifold flanges, changing the angle of the V mating surfaces to the head....
reinstalled it, and the problem went away....
then I faced the PVC venting problem which cured itself largely by breaking in the engine for 5000 miles....took that long...about a year....
I still have a bit of oiling in the plenum, but not so bad, and uses nary a drop between changes, so it's fine now....

I suspect your heads are 'angle milled'.....and no corrective action takenon the intake plane....

GENE

 

I had the same problem on my motor when I first put it together. I was going through #8 plugs like no tomorrow. As it turned out the valve stem seals were garbage. The orientation of the motor in a C3 worsens the condition on the rear two cylinders.

I noticed the burning when I was driving at night and had someone turn their brights on behind me. I could see the haze of burned motor oil as I got on it.

 

Gene, I have the invoice for my heads and it states that they were flat milled and the intake fixed. I did have sealing problems, but I'm now using RTV on both sides of the gasket and now it is sealing fine. When I pulled the manifold, I held the black light on both the intake and head and I could see that no oil was getting past the gasket/RTV and into any of the ports (head side or intake side). I do still have oil in the heads/manifold as evidenced by the dye, so I can only assume now that it is coming from the valve seals.

 

chris
there is a chance that the manifold is porous/cracked :eek:

i never used the dye technique, but it is puzzling that there is oil in there
:crazy:

 

I have seen some instances with aluminum heads where the top two valve cover bolt holes are drilled and tapped deep enough that they go into the intake port. It is best to use a stud with sealer and a nut for the valve covers. You should be able to check this if you still have the intake off.


[Modified by Pete79L82, 7:17 PM 7/1/2002]