Rear Main Seal.....

After my dyno session, I noticed some oil dripping from my bellhousing area. Am I to believe that my rear main has crapped out? The motor has maybe 20,000 on it, but it has never seen these boost numbers before. The PCV blew out, and i bought a check valve for that, but then i noticed this. I was thinking of maybe putting a hose on the Valve cover nipple, running an inline filter , and then to the powerpipe to help with ventilation. Has anyone done this? What about the main seal?

Yes i run a breather, and the hose from the TB to VC is gone before someone asks.

New leaks are fairly common as you may expect especially with 15#'s of boost. What brand of seal did you use on the motor when it was re-done? If you used one from a chain auto-parts store that may be the culprit, I've compared the quality of several seals & the one's you get from the dealer are usually much better quality than the typical seals offered at auto-parts stores.

Just some food for thought.

the shortblock was built by DSS. So whatever they use is what i got. I expected a little oil here or there, and this is not a pouring leak, but it is a leak. If I can get more crankcase ventialtion, will this reseal itself, or is it a for sure it needs to be replaced? This is the first time it has leaked.

I would first rule out any other possible locations of the leak before tackling the rear main seal. (valve covers, intake, etc...)

If it is a rear main seal, I'm not sure if it will reseal itself or not, after you increase the ventilation. I would contact DSS, since they built the motor and should know what type of seal was used.

Those are awesome numbers with that NOVI 1000!

thanks. I am not excited about doing the main seal, but if it needs to be done, oh well. what about my idea for crank ventilation, any input?

I would probably clean the top of the rear of the motor and then drive the car around to check for a leak. When you blew the PCV out, it is bound to deposit some oil on the back of the motor and the top of the trans.
Doug

i plan on cleaning it up very well this weekend, but the preliminary view showed it looking more like coming from the main seal, oil pan area in the rear. any input on my vent idea?

With a blower making a significant amount of boost, get used to a leaky rear main.

I change mine every few months and I can always tell that it had been seaping.

Quote:

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Originally posted by EL Doug
I would probably clean the top of the rear of the motor and then drive the car around to check for a leak. When you blew the PCV out, it is bound to deposit some oil on the back of the motor and the top of the trans.
Doug

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Exactly what Doug said!

Check your valve covers too! Make sure they are nice and snug. I had a valve cover leaking gremlin as well as the PCV valve occasionally popping out when I ran the 8" crank pulley.

Neil, I knew you would L O V E 8" crank pulley :D !!!!!!!!!!

Ya I've had the same experience, went through 2 rear main seals within a year and a half. You can get a new PCV, they are pretty cheap at the dealership for starters. Running the hose from your valve cover to the powerpipe with the filter might help but I'm not sure how much. I had the hose draining right before the air filter, don't think it helped any. Might work better if it was plumbed into the powerpipe. I had a new problem going to a vic 5.0 lower, there is no pcv provision so I just had the shop who put the motor together tap the lower for a large an fitting. Then just running a hose to a breather tank. I've noticed others having luck doing this so I figured I'd give it a go. Or you could take it a step further and rig up a moroso/fms vacuum pump in place of the smog pump. I thought I read though that the moroso pumps had limited life spans and were predominantly for race applications. Also heard of people drilling out the smog pump turning it into a vacuum pump.

There are lots of threads on corral about tackling the idea of relieving crankcase pressure which is the culpret of many leaky rear main seals which I'm sure you've read. I've run a breather etc but I think most of the problem/pressure is right in the crankcase.

any info on the smog to vac pump conversion? sounds good! The leaky rear main is not a big issue, it sucks, and seems like many people have it. i am going to put another breather on the drivers side cover, install my check valve, new PCV. clean up all oil, check all gaskets, and make sure all is well. then i am going to blast it down the track and try to see if i can have the fastest Novi 1k around!!!

Leaky rear main seal is normal in high boost applications and those engines w/some wear(Blowby)it's crank pressure.i would not change it.u don't accomplish anything...some type of evac sys would go a long way..ie two breathers..one way check valves etc as mentioned above...

i wouldn't consider my car one with blowby, it has super low miles on the DSS shortblock. Does anyone have any tips on putting a breather on the drivers cover with a cobra or long runner intake?

you could probably tap a hole on any side of the valve cover after taking it off of course, then weld some sort of baffle on the other side. Its probably the hard way but might be worth it in the long run. Probably be more worth it to do it to some sheetmetal valve covers that will fit under a long runner upper. Damn cars just eat money! Thats a bummer though if it turns out to be the rear main seal with so little of miles. What kind of numbers do you get on the cylinders as far as compression? My stock motor had 70k miles on it with decent numbers but it used oil around a quart every two weeks with about 15 miles of daily driving a day. The rear main seals just didn't seem to last long though. Someone mentioned to me about a rear main seal saver awhile ago also saying that worked like a charm. I've never had experience with them but was told you could get them at your local auto parts joint?

I read that on corral about the seal saver. sounds like a pain to install, but might be the best way to seal it up for a while.