One piece vs. two piece rear main seal

[JayDubBlazer]

I remember this as a topic several years ago but couldn't find it with a search. Which type of seal am I suppose to use? I have a non-emissions bare bones crate. Also, I thought there was a way to get the oil pan off without out pulling the engine. Is this true. Any help or advice would be appreciated. Trying to get all the materials so I can get my truck running over Thanksgiving.

Thanks

[ChevyDude]

BBC...I just went through this when looking for my builder block...all Gen IV big blocks are 2 piece rear main seals. My machist/builder guy said get 2 piece. I would assume any small block out of our trucks era , are two piece also.

[speed]

How old is the crate motor? GM changed from 2 piece seal to the one piece in the late 80's.
You can get the oil pan off without pulling the motor, it is tight though. For some more room you can unbolt the motor mounts and lift the front of the block with a cherry picker/ engine hoist.

[Longhorn Man]

ona 4X4 I wouldn't think it's a problem getting it off... I don't think it can be done on a 2 wheel drive.

[earl87gta]

I had to trans ams one was a 85 and one an 86 85 had a 2 piece seal 86 had one Piece so if your engine is newer then 86 I would say one piece rear seal. if you cant get the oil pan off with out plulling the engine you may just need to remove the motor mount bolts and lift it a inch or 2 to give you enough clearnce to clear the cranke shaft if its not droping down enough and its not hitting the vrank it the oil pan may have a bafl in it to keep the oil from sloshing around and the oil pick up tube may be catching it.

[chris71]

for chevy small block they changed over in 87, along with vortec heads and roller lifters, maybe pontiac did it in 86? idunno. this is what my sbc rebuilding book said.

[robin58]

Pretty sure Vortec heads weren't seen on truck 350's until the 96 year.

[chris71]

Originally Posted by robin58

Pretty sure Vortec heads weren't seen on truck 350's until the 96 year.

sorry, i was talking about chevy in general

[MylilBowTie]

Not all center bolt cylinder heads are vortec. Im pretty sure the vortec name was used on the 4.3 or whatever size six cylinders in the mid 80s trucks.

[earl87gta]

My dads 86 vet had a one piece seal too.

[oldiron]

Turn the engine over to #6 firing on the dist. this will turn the crank so the front jounal will clear the pan. Jack up the engine and put a 2x4 between the block and the mount or mount and the mount bracket. Had to do this on the road once. Takes about 2 hours of cussing.