Question : Distributor O-Ring Replacement / More

[Century7667]

I need to replace the distributor shaft o-ring on my 3100 motors. I have two of them, a '95 and a '96.

Question: Does the uppper plenum have to be removed to do this on the 3100. The earlier 3.1 does not.

Another Question: Is there anything else up there that I should address when the throttle body has been removed. Coolant bypass hose?

Thanks,
Ken T.

[1988GTU]

I need to replace the distributor shaft o-ring on my 3100 motors. I have two of them, a '95 and a '96.

Question: Does the uppper plenum have to be removed to do this on the 3100. The earlier 3.1 does not.

Another Question: Is there anything else up there that I should address when the throttle body has been removed. Coolant bypass hose?

Thanks,
Ken T.

UIM will need to come off and make sure its the Dis O-Ring. It could very well be the LIMG leaking.

[Century7667]

UIM will need to come off and make sure its the Dis O-Ring. It could very well be the LIMG leaking.

Pretty sure it's the o-ring. They both leak at the transmission side, and leak oil to the exhaust manifold (especially after oil change). The '96 I bought new, and the LIM was addressed under extended warranty in 2002-2003. Neither engine uses coolant or oil, and the '95 came with Ethylene Glycol coolant from the factory.

So, once I have the UIM off, is there anything else I should address aside from the coolant bypass? Neither engine (110k and 150k) appear to be near overhaul yet, so it could be a while before the manifold is off again.

Thanks,
Ken T.

[1988GTU]

Pretty sure it's the o-ring. They both leak at the transmission side, and leak oil to the exhaust manifold (especially after oil change). The '96 I bought new, and the LIM was addressed under extended warranty in 2002-2003. Neither engine uses coolant or oil, and the '95 came with Ethylene Glycol coolant from the factory.

So, once I have the UIM off, is there anything else I should address aside from the coolant bypass? Neither engine (110k and 150k) appear to be near overhaul yet, so it could be a while before the manifold is off again.

Thanks,
Ken T.

Unless u want to replace LIM's then nope.

[Century7667]

Unless u want to replace LIM's then nope.

Not really looking forward to a LIM job, no. Too much to do already.

It would be interesting to see a survey on this board to determine which years are most affected by the LIM failures. What coolant do you use, how many miles, what year is your motor. That sort of thing.

Ken T.

[geoffinbc]

Just ask GM LOL. At my dads dealership it was 95 to 02 that were the most affected. It was pretty much just a matter of when it would fail. Sooner or later they all did. All you had to do was be vigilant about checking the oil and looking under the hood and it was easy to catch in time. My dad got a lot of repairs done for customers just out of warranty, repaired under good will, plus even some that were years out of warranty done with GM paying half the bill. They put in new bolts and the revised gaskets with the new torque specs. They even bought a parts cleaning machine to tackle the huge load of repairs. The mechanic was able to throw the LIM and UIM into the machine for cleaning while they tackled other parts of the job.

[Century7667]

Just ask GM LOL. At my dads dealership it was 95 to 02 that were the most affected. It was pretty much just a matter of when it would fail. Sooner or later they all did. All you had to do was be vigilant about checking the oil and looking under the hood and it was easy to catch in time. My dad got a lot of repairs done for customers just out of warranty, repaired under good will, plus even some that were years out of warranty done with GM paying half the bill. They put in new bolts and the revised gaskets with the new torque specs. They even bought a parts cleaning machine to tackle the huge load of repairs. The mechanic was able to throw the LIM and UIM into the machine for cleaning while they tackled other parts of the job.

I think I'm going to take your words under advisement. GM already fixed my '96 under extended warranty back in '02, so I should be good with that one. The '95 however, has 110k miles, and if I am half way there, I might as well go all the way.

BTW, what year did the 3100 get the platinum plugs? The platinums can easily go 150k, but I don't know what's in this motor.

Thanks,
Ken T.