Ok, so for the past year I've had this excess crankcase pressure that I haven't been able to pinpoint. I've had great compression, brand new turbo, and rebuilt engine. During hard boost that valve cover breather will shoot off. About half a year ago I replaced all my front cover seals with new ones because I suspected they were leaking, and they were all soft and rubbery...still definitely good. Now, my rear main seal has been leaking like a seive and I suspect that the seal itself is good and it is just the crankcase pressure that it forcing oil past the seal. Upon doing my headgasket (which turned out to be not blown), the machinist told me my cylinder head was way warped from overheating. It is possible, that by simply resurfacing the cylinder head and throwing a new headgasket on there, that I won't even have to touch the rear main seal because that was the cause of the crankcase pressure? Or is it kind of a "once it's shot, it's shot" sort of deal?

1991 Mitsubishi Eclipse GSX - SOLD
2006 Mustang GT Convertible

Sorry I'm just getting to this Andy,

First thing, IMO change the seal regardless.
That being said,a little excess crankcase pressure will generally not hurt your seal IF it is only a little pressure for a little time. If this has been going on for 1 year, I can't see the seal being any good. Of course, if you're so inclined, you can roll the dice and and pull just the tranny later if you want to.
Now, what's going on with the blow-by. You said the comp was good but the cylinder head was so warped out due to overheating? And yet your crankcase is so pressurized that you are blowing out seals and breathers? That's pretty heavy.
If your comp numbers were good all across (which seems a little strange for a head that was that badly warped), I'm wondering if you have a broken ring landing. Did you do a leak down on the cylinders before you took off the head? A broken landing can give good comp numbers but will leak down quickly. It's just that you are talking about a fairly fresh rebuild yet an overly warped head and extreme crankcase pressure. Or maybe the rings were not gapped properly on the rebuild.

I'm not bustin' your balls or anything on this. I just hate to have you do all the work of reinstall only to have the same problem. Do your cylinders look OK or are there any outstanding scrapes in the walls? I'm sorry if this is more than you were asking, I just had concerns.

MB

Captain Caveman

96 RS Turbo 11.414 @ 119.62 MSNS, Crower 2 NA cams, BW366, 10.5 comp, UDP, 60mm TB, W/A intercooler, 3.55 tranny 567.9whp 430tq
97 RS NA 13.188 @ 103.87 MSnS powered 12.5 comp, Crower 3's and 219.4whp with 175tq
98 RS DD 12.5 comp on stock ECU, LTH, Crower 2's, Koni, GC, Hypercoil, DG hats
99 OZ 5sp Stocker 15.856 @ 85.97
99 GS stocker auto 17.7@77mph!

wiki home page:http://www.2gnt.com/index.php?d=bullettdsm

Bah, its a little too late now. I literally just threw on the cylinder head this morning. I was just saying this because I dont really have time to throw on a new rear main seal while I'm in town and I also don't want to waste $35 on oil when I get in there later. I was just being hopeful. When I come back home in a few months I will give the rear main seal a go and if that doesn't fix all my oil leaking then I will be forced to look into more serious problems. This stupid automobile. I should have definitely done a leak down before taking everything apart.

1991 Mitsubishi Eclipse GSX - SOLD
2006 Mustang GT Convertible

LOL! Well if its any consolation, you gave me a laugh on a kind of crappy day (I hope I was laughing WITH you ).

Yeah good luck with the car, and if your heading over "there" keep your Effing head down and godspeed.

MB

Captain Caveman

96 RS Turbo 11.414 @ 119.62 MSNS, Crower 2 NA cams, BW366, 10.5 comp, UDP, 60mm TB, W/A intercooler, 3.55 tranny 567.9whp 430tq
97 RS NA 13.188 @ 103.87 MSnS powered 12.5 comp, Crower 3's and 219.4whp with 175tq
98 RS DD 12.5 comp on stock ECU, LTH, Crower 2's, Koni, GC, Hypercoil, DG hats
99 OZ 5sp Stocker 15.856 @ 85.97
99 GS stocker auto 17.7@77mph!

wiki home page:http://www.2gnt.com/index.php?d=bullettdsm