rear main situation

[yellow1098Greg]

So a couple for months ago when I rebuilt my engine it had a problem with the rear main seal, in that it kept blowing the crappy little stock rope seal out in the rear main. After several times visiting the shop and many wrong guess I thought. I got one the Braided Teflon/graphite replacement ropes from Butler Performance and I thought the problem was fixed. Now since then I haven’t really pushed the car to much but the problem of it completely blowing oil out of the rear main seemed to be fixing because it’s been pretty much dry. Well today I went for a nice long spirited dry on the interstate and put my foot in alittle bit and when I got off the highway and parked I notice it was leaking a decent amount from the rear main spot again. Could it be a problem other than the rear main? Like blow by? Or something else? I hope not! Or could it be I need the next step up, heavy duty Viton Rear Main (also from Butler) that I believe goes over the crank and is one piece? And am I right in thinking the motor has to come out and the crank loosened to put this seal in? The motor is a 400 with around 400 hp with all edlebrock top end performer series heads, cam, and intake with forged pistons bored 30 over. Any helpful info would be greatly appreciated, thankyou.

[TT302Z28]

Hmm...I would be looking for crank case issues that allow pressure to build. Have the rings had time to seat yet? Takes around 200 to 300 miles sometimes depending.

[yellow1098Greg]

what kind of crank case issues could it possibly be? I believe they should have had time....its been about 500 or 600? its getting alittle frustrating

[TT302Z28]

1. Are you running a PCV and breather? This allows for a vacuum to draw out any blow by.

2. If there is a PCV, with engine running is there vacuum there? Pull it from the valve cover and put your thumb over it. It should have good suction and be steady not surging.

3. Do you have a major vacuum leak anywhere? Do you have power brakes? If you have a PCV installed and PB, how do the brakes feel? Does the peddle get harder to push if you use it 2 or 3 times in a row?

If these are all positive and the engine seems to be running right, is it possible there is too much oil in the pan? Any blow by?

The biggest suspect maybe too much oil, sure it is the proper dip stick for your pan?

[yellow1098Greg]

drivers side valve cover


passenger cover


pcv


oil cap and breather

Do u think this will all allow it to breath properly?

[ErikLS2]

Here is a good test for checking how well the crankcase is breathing:

1) Remove the crankcase vent tube, on the passenger valve cover in your case, the one without the PCV valve in it

2) Adapt a common vaccuum/fuel pressure gauge to seal well at the opening in the valve cover. Gauge should read at least 10" vacuum/10psi pressure. A common mechanical fuel pump/vacuum gauge from the auto parts store is perfect.

3) Insure the dipstick seals properly to the tube or seal the top of the dipstick tube with something. Also, find a way to seal up the oil fill cap opening, your vented cap wont work for this test.

4) Start the engine and let it idle (engine should already be at normal operating temperature) and record the vacuum reading on the gauge at 1 minute and shut off the engine. Should see at least 5 in. vacuum or so.

5) Pinch off the hose between the PCV valve and the intake manifold.

6) Start the engine and let it idle and record the reading on the gauge at 1 minute. Should see no more than 4 psi or so and don't let it run longer than a minute or let the pressure get above 8 psi.

This will tell you how well your crankcase is breathing. Most important thing is to seal all the openings up as instructed or the gauge reading won't be accurate. Post up the numbers if you like. Good luck.

[yellow1098Greg]

thanks ill give that a shot. asap

[Debonair]

What kind of engine are you running?
A Pontiac?
When the engine was reassembled was RTV applied to the rear main cap to keep oil from migrating out between the parting line?
If not, oil can weep from between the rear main cap and the block.

[yellow1098Greg]

thats a good question.....ya its a pontiac 400.....anyway to tell if thats the case? there does seam to be a thin line of oil all around the oil pan in certain places as well....is the only way to fix all this to pull this dam motor?

[anthonys 69]

try this link http://www.highperformancepontiac.co.../photo_07.html you can change this seal without taking the crank out push one end of the seal in and turn the motor by hand the same time you push in the upper half. good luck

[yellow1098Greg]

thanks giving this a shot friday...ill keep you posted