main seal

saniutza · Oct 18, 2004

rebuilded the engine less than 1500 miles on and the main seal leaks... just changed it saturday and it still leaks!!! wasn't changed by me but by a professional mechanic... is it because of the s/c? do i need some kind of a special main seal??? when i rebuilded the engine i bought the rebuild gasket kit from summit, i told them what i had and i told em i need a very good gasket set.... i have no clue why it's leaking again... i have a dss 7qt oil pan... a main support etc etc... anybody hasany idea what might be???? tnx

ratrapp · Oct 18, 2004

there are a few possibilities.first verify it's the rear main leaking by having some oil dye put in it and check to see if its not running down the back of the intake or valve cover.secondly you may just need a good ford seal in it,or you may have too much crankcase pressure generated by the s/c or from inadequate ring seal causing the rear main to blow out.the last reason could be improper installation or a worn or scared crank surface.

RydeOn · Oct 18, 2004

I use the Felpro teflon ones. Those are pretty durable. But any of them will be good for 1500 miles. Also, make sure its infact your rear main that is leaking. There are other seals back there that could be leaking that can appear to be a rear main.

v8only · Oct 18, 2004

often a rear main seal will leak if the crankshaft has been nicked or grooved at all during removal of the old rear main. the smallest of nicks can cause a rear main look. this is easily remidied by "sleaving" the crank. Not saying this is the problem, but it's very, very likely.

saniutza · Oct 18, 2004

hmm i see... i don't know what to say... does the S/C has anything to do with this... from what i know there;s no air/ pressure going down the botton end to push the oil out of the seal, right?

HISSIN50 · Oct 19, 2004

saniutza said:
hmm i see... i don't know what to say... does the S/C has anything to do with this... from what i know there;s no air/ pressure going down the botton end to push the oil out of the seal, right?

yes it will. how do you have it plumbed in terms of PCV stuff?

often one will hear a leaking-air sound while running and after shut down - suggests that the air flow is jacked (and squishing out the seal).

good luck.

Michael Yount · Oct 19, 2004

I'm with HISSIN - it looks like you don't have inadequate crankcase ventilation. Pressure building up in the crankcase will easily force oil out of brand new, perfectly good seals. You probably didn't need to go in and replace it - sorry about that.

Get into the power adder forum and ask the guys there about how they ventilate their crankcase to avoid the issue you're having.

saniutza · Oct 19, 2004

btw i said the main seal but it's the rear main seal that's leaking.... i talked to couple of the guys that i work with and one of them said that it might leak because my clutch might push the crank and the thrust bearing and the thrust bearing might be worn out and the crank might play and make the seal to leak.... i don't have any loss or oil pressure th pressure warm up idle it's over 40 and at cruising it;s over 50 psi... so i dont think the bearings are bad...

saniutza · Oct 19, 2004

HISSIN50 said:
yes it will. how do you have it plumbed in terms of PCV stuff?

often one will hear a leaking-air sound while running and after shut down - suggests that the air flow is jacked (and squishing out the seal).

good luck.

HISSIN50 said:
yes it will. how do you have it plumbed in terms of PCV stuff?

what do you mean, my PCV valve might be plugged???

HISSIN50 · Oct 20, 2004

saniutza said:
what do you mean, my PCV valve might be plugged???

with your forced induction (and positive pressure) you can have issues (PCV is somewhat bi-directional).
being sure the existing components are up to par is a good idea - though i dont know what mods you might want to make to fix the issues you have (i cant remember forced induction stuff i once knew).
good luck.

GT Trooper · Oct 25, 2004

I have the same problem. This started with a rear main seal leak (confirmed). It took me at least twelve hrs to change it out. Completed the install, let it run for a while and it leaked again, just not as bad. I then went to Ramcharges and got a felpro gasket and went through the entire istall all over again. Sucker still leaks a little. I don't know what to do about this one.

Michael Yount · Oct 25, 2004

GT Trooper - when you keep putting new seals in, and it keeps leaking, it's probably not the seal that's the source of the problem. I'd investigate crankcase ventilation. Sounds like pressure is forcing the oil past perfectly good (new) seals.

HISSIN50 · Oct 25, 2004

Michael Yount said:
GT Trooper - when you keep putting new seals in, and it keeps leaking, it's probably not the seal that's the source of the problem. I'd investigate crankcase ventilation. Sounds like pressure is forcing the oil past perfectly good (new) seals.

the man has spoken (and whahoo, i had the same thought as Michael).

saniutza · Oct 26, 2004

i bought a Supra PCV valve and replace it with the stock one.... i clamped the house and the valve and put it back in the motor... the damn seal still leaks... i assuse i might dammaged the seal, so i guess next step is to change it again....

Michael Yount · Oct 26, 2004

san - it may just be that with the boost, you're getting more blowby/crankcase pressure than your standard pcv hookups can deal with. Remember, under boost, the crankcase pressure most likely DOES NOT exceed your manifold pressure. That means whenever you're in boost, crankcase pressure has nowhere to go but out the seals. On a naturally aspirated set up, manifold pressure never exceeds atmospheric pressure. So even at wide open throttle, crankcase pressure can vent into the manifold. That's not the case with a boosted motor.

I don't think you have a seal problem. You're not effectively venting the crankcase under boost.

Do you have breathers on the valve covers - or vents on valve covers with hoses running to a vented catch can? It's probably gonna take a set up like that to vent your case under boost. Until you manage that - you're likely gonna keep blowing oil out the seals under boost, because the crankcase has nowhere else to vent to.

TT91 · Oct 26, 2004

get yourself a set of valve cover breathers and see what happens...

saniutza · Oct 26, 2004

Michael Yount said:
san - it may just be that with the boost, you're getting more blowby/crankcase pressure than your standard pcv hookups can deal with. Remember, under boost, the crankcase pressure most likely DOES NOT exceed your manifold pressure. That means whenever you're in boost, crankcase pressure has nowhere to go but out the seals. On a naturally aspirated set up, manifold pressure never exceeds atmospheric pressure. So even at wide open throttle, crankcase pressure can vent into the manifold. That's not the case with a boosted motor.

I don't think you have a seal problem. You're not effectively venting the crankcase under boost.

Do you have breathers on the valve covers - or vents on valve covers with hoses running to a vented catch can? It's probably gonna take a set up like that to vent your case under boost. Until you manage that - you're likely gonna keep blowing oil out the seals under boost, because the crankcase has nowhere else to vent to.

i do have a breather on one of the valve covers... do i need another omne on tje other valve cover????

TT91 · Oct 26, 2004

one should be enough, but two wouldnt hurt. Moroso makes a nice weld in kit if your looking for something permanent. Downs ford motorsport also has a kit.

saniutza · Oct 26, 2004

sirsureshot39 said:
one should be enough, but two wouldnt hurt. Moroso makes a nice weld in kit if your looking for something permanent. Downs ford motorsport also has a kit.

i don't know... i'm getting so frustrated... i don't know what to do, i don't know where to start... i dont wanna pull that engine out again, or the tranny... like i've said i changed the PCV valve with a supra... today i got up on boost and chacked it afterwards and it's still there, so it's holding up..i don't know why it's still leaking... i got couple of pics of my engine maybe somebody can tell me if there's anything wrong...

saniutza · Oct 26, 2004

whats up with that line thats on the TBand goes to the oil fill??? is it a vacume line??? does that hve anything to do with my crankcase pressure? i 'm thinking removing the s/c bet for couple of days and see if it still leaks...

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