The engine is a 305ci crate motor, 21k miles. I have an oil leak. This leak only appears under certain conditions, and not consistantly even then. First, the leak appears to be near the rear of the drivers side of the motor. It wets the sparkplug and plugwire boot on cylinder 7, and on down the side of the block. The valvecover is completely dry, I replaced the distributor gasket when I switch from the computer to vaccum, and I can't find a leak on the intake manifold, its appears to be dry, and is torque down properly. First, this leak does not occur at idle, or even cruising. It only appears under heavy load, usually with higher rpms. I see it the most when I pull out to pass at like 60mph, shifts down to third, runs up to about 4500rpm, and after a few seconds I can see, and smell the blue smoke behind me. Its not coming out the exhaust, its burning of the drivers side header. I pull out of the throttle and it'll clear up.

If I'm just crusing along, I can put it in neutral and hold the revs at like 4500rpm, no smoke at all. It's defintley only under load/low vaccum. It will occur at any speed. Its not losing much oil, it doesn't leave more than a drop or two on the ground when I park it. I was thinking head gasket, but I have no oil or coolant contamination, so I'm hoping there is something else I'm just blatently missing. Any thoughts?

 

It almost has 2 be a valvecover gasket. Head gaskets tend to leak into the cylender and not to the outside of the motor and wouldnt leak up 2 the sparkplug.

 

Oil doesn't go through the head gasket anywhere.

 

Let me guess...

Smog pump has been hacked off of it, right?

 

You're thinking the upper hole here?
https://webdisk.ucalgary.ca/~jmknopp...de%20motor.jpg

That's passenger side, and low down though.

 

The smog pump is gone, but if your thinking about the hole you get near the fuel pump, its been left bolted up to prevent that leak. The leak is back on the rear of the drivers side head.

I've heard that, and thats what I've thought, its just right down there at the block/head mating surface, was causing me some concern.

 

You're sure it's not a valvecover gasket?

 

It is dry. The only possiblity, which I guess I haven't considered, is that it sprays directly out, and does not get the top of the head wet anywhere. I did check all the valvecover bolts, it is secure. I guess its going to require some further investigation, maybe I can have somebody brake-torque the car while I look for the leak.

 

Is the #7 plug tight?

 

If oil is dripping on a header pipe it's GOT to be the V/C gasket.
Here's what I think is happening:
When the throttle opens past 1/2 throttle the flow thru the PCV valve slows due to low manifold vacuum. If it's holding a slight vacuum in the crankcase this probably changes to a slightly positive pressure.
(where's that graghic of Calvin peeing on a ford?)
At the same time the temperature of the header pipe soars when the load goes up on the engine.
If the sparkplug isn't loose the V/C gasket is the only source if oil on the outside of the head.
C'mon change the gasket. It's the "easy" side...

 

The logic makes sense, I will pull the valve cover and replace the gasket, its the easy place to start. I just moved into my first house this Monday, complete with a two car garage. Needless to say, the Camaro is finally being garage kept, and is in a suitable all-weather work environment.

 

Could it be blow-by from the dipstick? I dont know what side your dipstick is on...

 

Nope, its a passenger side dipstick...

 

Some blocks have provisions for dipsticks on both sides. You have to plug the one you aren't using, if your block is so equipped.

 

Perhaps a leaky plug. This 305 is not the original motor, this was a crate motor placed in the car in the mid 90's, it likely does have the provision for the dipstick on either side. Thanks for the insight, thats another possibility I hadn't even considered.

 

I dont know what it is but the is a oil fitting located near the top on the back of the block on the drivers side. Mine did the same thing till I got pissed and did a engine swap.

 

Intake manifold leak. I had one do that, it made me crazy for MONTHS! But it wasn't until it also started leaking antifreeze that we figured out what it was. It would ONLY leak oil under specific conditions. (aluminum and iron don't work and play well together)