What could cause this? Update

Ballaholic29414 · Member Joined: 01 Sep 2008 Posts: 71 2595.20 points

Small amounts of oil blowing from the back of the intake behind the distributor. It was doing that before I changed the head gasket and still after I changed the head gasket. It doesnt leak on the ground it just sits on the block when the tranny and block connect. It was also coming up the distributor but we put silicon around the gasket and that stopped it. I packed some more silicon around the back of the intake before I went to the track last week and that slowed the leak down, but what could be causing this?
I do have a Crankcase Evacuation Kit.

It only does this at high rpm because I only see it after I make a pass.

af2 · Posted: Wed Jun 03, 2009 4:35 pm Post subject:

I never use the supplied front and rear gaskets on any Chevy intake. A thick bead of silicone works every time. If you have a leak you know it wasn't thick enough. 1/4" bead works. Wipe off the excess and they will think you own an Olds! Shocked

Ballaholic29414 · Member Joined: 01 Sep 2008 Posts: 71 2595.20 points

clay · Posted: Wed Jun 03, 2009 7:59 pm Post subject:

I'm assuming you're talking about a header style evacuation kit. I don't know how well those work with mufflers. You could do a quick test by installing a "T" in the header evacuation line and see if you pull vacuum or build pressure while going down track. Only other thing that should affect crankcase pressure is the valve cover arrangement but it sounds like those didn't change. You might just be lucky like me and there is nothing wrong, it just decided to start leaking right after you bought it. Try the vacuum gauge though - it might show something. Clay

lun40119 · Posted: Wed Jun 03, 2009 8:14 pm Post subject:

I tried a header evac setup with a 2.5" flowmaster exhaust, and it spit the dipstick tube out. Pulled the hoses off, and put in a regular breather, and all was well. I wouldn't use those with mufflers. Good call Clay. I still have the headers with the bungs welded in them, if anyone wants them Laughing

10sec.et · Posted: Wed Jun 03, 2009 9:20 pm Post subject:

Ballaholic29414 · Member Joined: 01 Sep 2008 Posts: 71 2595.20 points

Knarley Darley · Member Joined: 22 Apr 2004 Posts: 1158 537254.14 points

I think the mufflers are to small and that is where your E.T. went. You can do a quick test of your evac system by pulling the hose off at the valve cover, put your finger over the end of the hose and rev the engine. You can feel if it has pressure or vacuum. If it has pressure then for sure the mufflers are causing back pressure and are too small in diameter.

Ballaholic29414 · Member Joined: 01 Sep 2008 Posts: 71 2595.20 points

Ballaholic29414 · Member Joined: 01 Sep 2008 Posts: 71 2595.20 points

Took the mufflers off and the leaking stopped