Rear main leak brand new X2!!

[3XTurboAgain]

Had my motor rebuilt '90 3.1. Got it back and installed , leaked right from rear main area. Changed oil pan gasket, no luck, took motor back out and had machine shop redo their seal. Put motor back in and... still leaks from rear main seal ! Now my question, what did i do wrong? Is there a spacer inbetween the flywheel and crank or is it on the outside? I remember putting it on the outside of the flywheel... is that right and would that make the rear main seal leak? Trying to terminate this problem!! thanks!

[gpse3400]

There is supposed to be some RTV between the rear main cap and the block. If that is not there then you will leak from that area.

[ForcedFirebird]

There is supposed to be some RTV between the rear main cap and the block. If that is not there then you will leak from that area.

I alway thought that was on two-piece seal engines?

[3400-95-Modified]

Nope, that is true for 3400's too, I didn't put that RTV there on my first 3400 build and the motor had to come out on its 500 mile oil change to fix that problem. Needless to say the oil change took a little longer than 15 min.

And you put the spacer in the right spot, it goes on the outside of the flywheel its like a washer for the bolts.

[3XTurboAgain]

there is really supposed to be silicone on a 1 piece? Im making the machine shop pay for this!! Should i tell them to use silicone on the rear main? I really have to take care of this. Last time they wanted me to drop my car at a transmission shop to take the tranny down to redo the engines rear main, i refused because i didnt want anyone touching my car so i took the engine back out... now i dont give a shit i just want it fixed and i dont feel like taking everything back out.... I put too much time and money into this car and i cant go to the track with a leaker.

[ForcedFirebird]

Nope, that is true for 3400's too, I didn't put that RTV there on my first 3400 build and the motor had to come out on its 500 mile oil change to fix that problem. Needless to say the oil change took a little longer than 15 min.

And you put the spacer in the right spot, it goes on the outside of the flywheel its like a washer for the bolts.

Odd, usually one piece seals don't require silicone between the caps. I even dug out the manuals and they don't mention it.

I'll have to pull the pan/cap off the 3.4/3500 hybrid (still on the stand fortunately) and put a dab on there for security.

[3400-95-Modified]

GM 3100 overhaul procedures from my Beretta manual

INSTALLATION
Install upper main bearing in cylinder block. Ensure lock
tab is properly located in cylinder block. Install bearings in main
bearing caps. Ensure all oil passages are aligned. Install rear seal
(if removed).
Ensure crankshaft journals are clean. Lubricate upper main
bearings with clean engine oil. Carefully install crankshaft. Check
each main bearing clearance using Plastigage method. See
MAIN & CONNECTING ROD BEARING CLEARANCE in this article.
Once clearance is checked, lubricate lower main bearing and
journals. Install main bearing caps in original location. Install rear
seal in rear main bearing cap (if removed). Some rear main bearing
caps require sealant to be applied in corners to prevent oil leakage.
Install and tighten all bolts except thrust bearing cap to
specification. Tighten thrust bearing cap bolts finger tight only.
Thrust bearing must be aligned. On most applications, crankshaft
must be moved rearward then forward. Procedure may vary with
manufacturer. Thrust bearing cap is then tighten to specification.
Ensure crankshaft rotates freely. Crankshaft end play should be
checked. See CRANKSHAFT END PLAY in this article.

[ForcedFirebird]

GM 3100 overhaul procedures from my Beretta manual

Mine is a Gen1 3.4, and checked 3.1 Firebird manual.

Like I said better safe than sorry, lol.

[3400-95-Modified]

Still the 3100 was a once piece rear main seal, thats why I used it as an example, and the 3.1 3.4 3100 and 3400 blocks are pretty much identical when it comes to crank main bearings and mounting since well you can put a 3.1 crank in a 3100, well really they are the same crank...

[ForcedFirebird]

Still the 3100 was a once piece rear main seal, thats why I used it as an example, and the 3.1 3.4 3100 and 3400 blocks are pretty much identical when it comes to crank main bearings and mounting since well you can put a 3.1 crank in a 3100, well really they are the same crank...

Oh, I'm quite fimiliar with the 3500 and Gen1 blocks, I have Four cranks at the moment (all 981's) One is a true Gen1, no reluctor notches

[3XTurboAgain]

Ok so ill have to replace the seal and put silicone around it... sounds like a plan hope it works! Sucks pulling the motor again but it will be worth it. Sounds like a good time to replace rack , lines, subframe mounts/bushings...PMIII ... on and on ....

[ForcedFirebird]

Ok so ill have to replace the seal and put silicone around it... sounds like a plan hope it works! Sucks pulling the motor again but it will be worth it. Sounds like a good time to replace rack , lines, subframe mounts/bushings...PMIII ... on and on ....

Not around it. Take the rear main bearing cap off and put silicone between it and the block (oil pan has to come off).

[3XTurboAgain]

ok so between the rear main cap and the block and thats it? What about the seal itself? doesnt that get tapped in? Sorry for the confusion

[Joseph Upson]

ok so between the rear main cap and the block and thats it? What about the seal itself? doesnt that get tapped in? Sorry for the confusion

I've noticed a good bit of sealant at the rear main cap joint and the oil pan gasket as well as between the cap and block itself on the engines I've disassembled.

[3XTurboAgain]

Ok so im definately going to make sure i do this right this time. Would anyone happen to have pictures ? Also , is there anyway i could prove to the machine shop that they were supposed to use silicone? If i could prove this with a GM manual or soemthing i could probably get some of my money back for the inconvenience of pulling my motor for the 3rd time!