1998 LS model with the 3.0L 6G72

 

Mine is a 3.5L 6G74. It must have different injector flow requirements than yours. That's why different colors.

 

Mine were orange.

Good luck Hunter

 

Well, my Montero keeps kicking me in the a**...
Got everything assembled and installed the rebuilt engine into the car. All nice and tight, no coolant leaks, no oil leaks, until i drove about 30 miles...
Massive oil leak between engine and transmission. Lost about a quart of oil. I'm thinking my bad - didn't seat the seal correctly. Pulled the engine out again, and yes - rear main seal is cockeyed and part way out. No problem, like I said I seated the seal to just flush with the aluminum casing, so i figured it was my mistake. Ordered another seal, replaced it. This time seated it ALL the way until it bottomed out on the inside of the seal carrier. Put engine back in and drove around a little. Engine runs like a dream, smooth, quiet, lots of power. In other words all systems seem to be good. My wife took the car for a 80 mile round trip and... we have a leak between engine and transmission. Once again, its missing a quart of oil (judging by the level on the dipstick) and I suspect the seal came out again. I can't for the life of me figure out what is going on. The engine runs great, no misfires no shaking. I've done a leakdown test on it before first install. Each cylinder tested at less then 3% leak down. Which means it is supper buttoned up and should not have any excessive blow-by. I've tried National seal and Mitsubishi OEM seal. Both came out. What am I missing? Am I supposed to "glue" in the seal into the casing? Please enlighten me because this is going to be round 4 of pulling the engine out. I'm getting pretty good at it. I bet you I can do it at night without even using a flashlight now, but I can't keep the darn seal in place.

 

Have you checked the PCV valve? If it's inop, this this might cause a buildup of crankcase pressure. Another idea, is to check and see if the new seal is placed in the same exact spot as the old one. I've heard that when installing a new cam seal or crank seal, that you don't want the new one sitting in the old seals wear groove(this groove would be located on the crankshaft/cam shaft). You may not be able to really feel it with your finger but you should be able to see it, just position it slightly off.

 

Yep, first thing I checked was PCV valve. One way operation only. I did have gunk buildup in the intake tube where vent hose terminates, but I cleared it out during rebuild.
I'm aware of thevseating the seal slightly in different spot. If there is a wear groove from old seal, it may cause the newcseal to leak. Mine just comes out. I dont think this can be explained by the possible groove. Plus my crankshaft was polished during rebuild (not ground, just polished). So, if there was a groove, it would be removed.

 

Hmm, I wonder if they machined the crank end? If they did then you'd need a sleeve to go over the end to bring it back to spec.

Edit:
I know you said it wasn't ground but it seems to me that somehow, an amount of material had to be removed for this issue to happen if it's not an excess of crankcase pressure(which it appears it's not).

 

Hunter......Mannnn, that is terrible news....you have alot of patience to do this over and over.....alot of guys would have grabbed their .45 Colt and put the Mitsie out of her misery. My first thought was excess pressure build up, and the weakest seal will pop out first. Is the Oil Pressure running on the high side also? Is there a relief valve or adjustment to keep oil pressure from getting too high?

Like Naeos said, I also wondered if the circumference of that seal opening had somehow been machined or become out of spec.
Is there anyway to put a flat washer on the outside of the seal next time? Maybe the right size washer will kinda fill the air space and keep the seal from popping out?
Or, use some type of super glue and maybe that will "lock" it into place? I wonder what the next seal would be that might "pop out" if the rear seal stays in?

Best of luck on solving this riddle.

 

If the crank was machined, then the seal would be loose on the inside. This would cause seal to leak, but not to pop out. When installing both seals, you definitely need to "massage" it to slip it over the crank end. I'm 100% sure that this is not the explanation of my situation.

 

I don't have oil pressure gauge, just the dummy light for low oil warning.
There is no chance at all that the seal seat area was machined out - that part is a separate carrier and it stayed home.
There is no way to add any sort of washer to hold the seal in place. But it makes me wonder if there is supposed to be a sealant or some kind of cement added to keep it in place. Need to find a Mitsubishi mechanic to talk to...

I almost think that my next step is going to be another leakdown test (after rings went though break in process).