well here it goes, i just had a fresh 360 lt1 built with new everything, top to bottom. it has ported heads, hot cam, 1.6 rr, and full bolt ons. currently i have only 700 miles on the rebuild, i have been gentle on it breaking it in. i have oil spraying out of the dipstick due to i guess i have too much crankcase pressure at half throttle. ive checked everything and replaced the pvc valve. whats my problem? what can i do. i heard if my air filter isnt flowing it might cause negative backpressure and might cause this. brand new motor shouldnt do this. please help!

 

buy a manometer. Pull the hose off the PCV valve. Do a leak down test if that fails to show the problem.

 

No way a dirty air filter is causing that problem. If may also be blowing oil back into the throttle body through the line connected to the passenger side valve cover.... might be worth checking that before you load up the nitake manifold with gunk.

 

I'de put a couple breathers on it to relieve the pressure until you find out what the problem is, and like injuneer said to keep oil out of the intake. Are you sure your rings are sealing?

 

I agree with speedy, do a leak down test.
Mike

 

why wouldnt the rings be sealing? its a brand new motor, do i have to wait a little bit longer on the break in?

 

I implied through the order of suggestion that he get a manometer first and while using it, remove the hose that is plugged onto the PCV valve.

The reasoning behind that suggestion is I would have a tendency to believe the easier problem first. Since it appears that the crankcase is pressurizing instead of being in a vacuum, it would make sense to suspect the venting system (PCV) for the crankcase first. If the hose were plugged up, it would keep the PCV valve from venting the positive pressure and thus cause positive crankcase pressure instead of negative pressure (vacuum) like it should have.

I would not suspect rings at this time since he only mentioned the oil from the dipstick. He did not mention blue smoke from the tail pipes or missing or spark plug fouling. Since that is what you would expect from pressure escaping past the rings. HOWEVER, I did mention to check it with a leak down tester if the test with the manometer fails when checking the PCV valve.

I would also suspect if the PCV valve were working correctly but one of the pistons say had misinstalled rings. The PCV should still vent more positive pressure than one cylinder could produce. Again remembering that he isn't smoking, missing or fouling.

 

What speedy said, check the PCV.

 

I don't think rings are the problem, but these would be connected in my mind.

 

agreed, with roller cams, beat on them, it seats the rings better

 

Its very hard for significant pressure to build up in the crankcase due to a failed PCV valve. The pressure would simply escape out the vent hose on the passenger valve cover. Significant pressure is a sign of excessive blowby.

 

well im not getting any oil in the throttle body or in the hose going to it. the pvc valve isnt oily or dirty. one question, it seems like the dip stick is missing that little rubber o ring at the very top. its in but really doesnt feel tight. is it possible that due to this the pressure is popping it out bc of the loose fit. do i just need a new dipstick?

 

I agree with Injuneer. There is only one way to get excessive pressure in the crankcase. Pressure is blowing by the rings and pistons. Hopefully its the rings and they will still seat for you.

 

There shouldn't be enough pressure in the crankcase to blow out the dipstick with a tight seal or loose seal.

 

Most of the pressure in the crankcase is vented through the fresh air hose that goes from the tb to the valve cover since one of the jobs of the pcv valve is to restrict flow. And the pcv never puts the crankcase in vacuum, it just pulls fresh air from the tb into the passenger side valve cover to replace the air that was pulled out of the crankcase.