Ok, here we go: So I got my new motor running this last weekend and everything starts out peachy. As of sunday night, I had my car up on a lift and no sign of fluid leakage anywhere. GREAT! So yesterday, after putting about 300 miles on the motor for break in, I decided it's time for some WOT. So I did 5-10 WOT runs, great oil pressure, great pull, everything is seeming very good.

I get home, start to take off my wideband equipment and notice a glaze of oil has splattered and blown all over the underside of the car. None of it was dripping or anything, just looked like what oil would if there was a trickle that was blown down under the car from vehicle speed. So I am thinking DAMMIT... So this morning I check my oil level, was topped off, no additional drips on the driveway, so I take off the intake since it seems the leak is coming from the back of the motor.

When I pull the intake off, I am amazed to see that all 8 head intake ports have oil stains where the intake manifold seals to them and that is where the oil is leaking from. The oil seems to be confined in the in b/w the intake head port and the manifold runner, minus that fact that a small amount is leaking by the O-ring seals. Now I know at over time oil will make it's way into the intake system but as for 300-350 miles and having a catch can on the PCV as well, this seems way too excessive. Also to note, the catch can is filling up much faster than it normally does.

Somehow oil is getting into the intake stream but I have no idea why or how. When i look into the TB opening of the intake, the floor of the intake has a glaze of oil on it, and when i look down the runner, the first 2-3 inches are oil soaked, but what is interesting is that the top of the intake runner does not appear to have contact with any oil. Looking down the head intake ports, the whole head port is oil soaked, the valve, etc. Not puddled or anything, just glazed over. And again, I think this is a bit excessive for a brand new motor. The oil was somehow leaking out b/w the O-ring seals of the Intake Manifold where it mates up with the heads and getting blown to the back of the motor and thus finding its way down around the bellhousing to the underside of the car.

Here's a few other things to note:

1) The MAP sensor had come unsealed and was not tightly located in its hold. Most likely causing a small vaccuum leak. Would this have any effect?

2) Everything was hooked up as it should be, trust me... did not break the oil pressure sensor. The oil is only coming from where I described above.

3) Could overfilling wth oil cause this? used about 1/4 a qt for the oil filter and then 5 3/4 qts for the engine (doesn't seem like this would make much a difference but i'm open to anything)

4) Valve seal break? Unlikely that all 8 intake valve seals broke but just coming up with ideas...

5) possibility of oil coming up through the piston rings? Again, unlikely with the intake stream moving everything into the combustion chamber...

6) PCV malfunction of some sort? I mean it obviously works since I am getting lots of oil in the catch can, but what is causing this excessive flow?

7) The 3 days I drove around for break in showed no leakage of anything, I stayed under 3500 rpms for most of that period, so it seems like this is related to WOT since yesterday was the first WOT sessions and yesterday was the first time I see oil leakge. BTW, oil pressure is as it should be.

Whew... ok thanks for actually reading all that, can anyone help troubleshoot here? Thanks

Will

 

sounds like PCV issues, nothing else would create oil film in the intake like that. How good is your catch can?

 

and which catch can are you using?

 

second the pcv system just stick a breather on it................eliminate the pcv system

 

not a fancy dancy one, its an air/water seperator but it has never failed before. I realize that some oil will still get through, but I've had it for almost two years and never had this much oil in an intake...

On the other side of things, I did find something out. The knock sensor seals on the valley cover were not seated, allowing a small passage for oil to exit the top of the motor. This is most likely another source of oil leakage, but it still wouldn't necessarily explain the excess oil in the manifold now would it?

 

Get a catch can with a partitian that goes all the way to the top of the can and has only a small gap at the bottom of the can. That way the oil would have to go to the bottom of the can and work its way over to come out of the "out" hose. I believe that TXCAMSS (James) is running this type of catch can on his car and has had very good success with it. Have you done the LS6 PCV system? If not, that would be good to do since you have the intake off of the car.

 

Ditch the PCV system and put some breathers on it. this happened with my last couple of motors. one was PERFECT. the water/air seperater that your using is what i had and it worked GREAT. swapped motors and this one had excessive blowby and the little catch can could no longer keep up. it ended up blowing out the front and rear seals of the motor and i had oil all over the bottom of my motor and car ( just like you). On the dyno you could see the oil spraying out of the front main seal (all this only happened at WOT). i swapped out the seals and put a breather on each valvecover at the same time. no more PCV lines going to the intake so ABSOLUTELY no oil in the intake and the seals are PERFECT.

 

I agree you should see the oil with 17 psi ..............breathers solved it.

 

The only thing bad about breathers is that they leave a nice film of oil all over your engine bay. On that '69 I had with the LS6, I originally had a breather filter on each valvecover and each time I'd run it hard there would be a fine mist of oil residue along the valvecovers and blower. It was a PITA to keep all that chrome/polish clean, so I ended up slapping a PCV system back on the engine for Power Tour.

 

just get a good catch can and a LS6 oil valley and pcv.


thomas

 

Ok here's another question, let's say I am having some blowby, not only would I see excessive oil in the intake, would this be accompanied by lower oil pressure? My oil pressure is "ok" on cold starts it jumps way up to 50 psi idle and settles in to 30-35 once hot. Driving around I get roughly 40psi through most rpms, at WOT it only seems to get up to 50 psi. Is this effective enough? I always though rule of thumb was 10 psi/1000 rpms... My old setup, I'd push well over 60 psi at WOT. I do have a ported pump as well. I would also expect a bunch of soke from the exhaust since I'd be burning up all that blowby oil as well...

I know the front main seal is not leaking, but if the rear main seal was busted, wouldn't I be getting oil dripping out of the bellhousing and also getting oil all over my clutch, thus slipping it a bunch?

 

no it would drip near the back of the pan.

 

Suff them with big chunks of SOS cleaning sponges...............

 

which is right where the bellhousing meets the block, and I would be getting oil all over the back of the flywheel which would more than likely fling oil all around in the bell housing and I would see drippage coming from where the housing meets the block.... right....

 

Any news?

B

 

I still want to say its the PCV. We both have the same set up PCV wise, but sometimes on high rpm/deceleration oil will get blow right through the motor and end up all over my back bumper. Its not enough to tell on the dipstick, but its enough to smell out the exhaust.

 

sounds like an issue with the rear main seal that happened when i put a AMC V8 in my 79 jeep and i drove it home and floored like once or twice and when I got home oil was all over the place and I knew right then the rear main seal blew.