I had the LT4 hotcam installed along with LT4 heads and intake and the 1.6 roller rockers. After the work was complete I noticed oil leaking somewhere from the front underside of the motor. The "shop" says That because of the cam lift and duration and overlap I have less vacume and that the stock pcv set up is insufficient to reduce the crank case pressure causing the oil to leak through the front of the oil pan. They say I have to install a breather cap and or install a vacume pump. Does this make sense?

 

:bs :eek: I never heard of that! Now granted a large cam will have less engine vacuum. But a Hot cam is not is large cam by any means and the reduction of engine vacuum with that cam is not the cause of the oil leak. If that was the case my engine should be spewing oil with the cam I have! I have personally never seen a large cammed engine leak on account of "low vacuum"........

Remove the breather tube on the right valve cover, and rev the engine up a few times. See if there is any vapors coming from the breather hole in the valve cover. That breather tube on the LT1 is plumbed directly to the filter side of the throttle body. If there is any excess pressure it will be vented there as well. If you have that much pressure that would cause an oil leak I would suspect there would be other problems such as obvious blow by when you remove the oil filler cap from the valve cover.

I would go to another shop have it lifted so you can ID where the leak is coming from. The only way to get a oil pan to seal around the front cover correctly is to remove it and replace the one piece pan gasket. I have seen some shops short cut this because they don't want to remove the oil pan, instead they will goop it up with silicone and hope that it seals. Plus installing that front cover is a real PITA without removing the pan. Lift the car take a look if they used silcone its pretty obvious. Taking that pan off is pretty easy in a C4 and there is no reason to not do it right.

 

I just had a complete motor done with the LT4 Hot cam and it does not leak a drop of anything. Has to be a bad gasket somwhere. Does yours idle good mine does like crap.

 

How bad does it idle? I am running a 224/236 Comp custom cam and I have a very stable idle at 775 RPM. Did you or anyone do any tuning to the PCM? Generally you can get away without it but some need it.

 

It's leaking around the crankshaft hub. The reason it is leaking is that the original rubber seal wears a groove into the metal hub. Once you take it apart it will never seal again unless you either put a sleeve over the hub, or replace the hub.

Be sure to use a new seal when you do either one of these.

Sounds to me like the shop doesn't want to fix it. Granted it's not really their fault that it's leaking, but they should at least give you a straight answer.

BTW that's just the most likely, there are a few other options:

The timing cover gasket itself could be leaking
The water pump drive seal could be leaking
The opti drive seal could be leaking
The oil pan gasket could be leaking where it contacts the pan

The water pump is one of the best becuase it really requires a special tool to install correctly, something I'm betting they didn't have.


[Modified by Nathan Plemons, 11:40 AM 10/9/2003]

 

I'm frustrated by this leak. Mine idles pretty good. It does have a little lope to it though. maybe a little more than I expected, But I think it sounds tough. Definitley not a stock- like idle

 

Not too bad an idle. It does have a lope to it. I got a chip done for it