350 rear main seal

djw&cjw71lemans

New member
33
0
0
Massachusetts
Dealing with a difficult tranny leak. The shop is going to take it out and reseal everything. They said they would do the rear main seal also IF it's a one piece seal. Apparently GM made a two piece seal and then changed to a one piece. The two piece are very problematic and difficult to replace etc. so I'm trying to find out if my 1971 lemans sport 350 has the one piece rear main seal or the two piece. Does anyone know what it has or when the change to one piece took place? Thanks.
 

92 Sunbird LE

Well-known member
2,311
60
48
Salinas, Puerto Rico
Can be done with the motor in the car but oil pan has to come off and the rear main cap also.( they make "fishing" tool to get the top half out)

If it aint leakin , dont mess with it............IMO;)


Doug in P.R.:cool:
 

melsg5

Staff member
SUSTAINING MEMBER
22,399
299
83
sounds like you are confusing Chevy 350 and Pontiac 350. The Chevy 350 over the years switched from a 2 piece to a 1 piece. Pontiac never did. Hope your shop knows what they are doing.
______________________________
 

92 Sunbird LE

Well-known member
2,311
60
48
Salinas, Puerto Rico
Correct.............it can be changed at another time with the trans in the car if it starts to leak.

I would only trust that job to an old school mechanic.....not many nowdays have ever changed one.

Doug in P.R.:cool:
 

djw&cjw71lemans

New member
33
0
0
Massachusetts
Thanks. What I may not have made clear is I am pretty sure it is leaking as well as the transmission. There is definitely oil coming from that area. We will know more when the tranny is out this week getting resealed I hope.
 

melsg5

Staff member
SUSTAINING MEMBER
22,399
299
83
Why do you think the factory stopped using them?
Rockauto lists them to 79, last year.
Aftermarket Pontiac vendors have viton seals.
 
Last edited:

cammerjeff

Active member
736
45
28
Belleville MI
melsg5 is correct,

The factory used rope rear mains on all V8's thru the end of production of the 301's & 255's in 1981. If yours has a non rope seal it has previously been replaced with an after market seal. If yours has the rope seal I would suggest making the change to the aftermarket viton seals. The original rope seals contained asbestos that is not used in the modern replacement rope seals. The modern replacements do not seal as well as the original rope seals.
 
Top