rear main crank seal

kenh · Aug 23, 2020

1990, c1500, 5.7 (350) engine, auto trans.

From those that have done it, if it can be done, how hard of a job is it to replace the rear main crank seal in the vehicle? Can it be done without removing the trans? I've developed a fairly big leak in that area. 90% sure that is where it's coming from. Need to do a bit more investigating!

Thanks!

Ken

Supercharged111 · Aug 23, 2020

If you can slide the trans and t-case far enough back you could sneak in there. I don't think the t-case would play ball though. I yanked mine along with exhaust and cleaned all that up. It was NASTY. Yours will be too if you have a decent leak back there.

PlayingWithTBI · Aug 23, 2020

Take a look at your oil pressure switch on the back 1st.

alpinecrick · Aug 23, 2020

kenh said:
1990, c1500, 5.7 (350) engine, auto trans.

From those that have done it, if it can be done, how hard of a job is it to replace the rear main crank seal in the vehicle? Can it be done without removing the trans? I've developed a fairly big leak in that area. 90% sure that is where it's coming from. Need to do a bit more investigating!

Thanks!

Ken

Yes, the trans has to be moved back or moved sideways to access the seal. At least yours is a 2wd.

As TBI mentioned, make sure it's not the oil pressure sender located at the back of the engine--it ain't easy to see or get to.........

kenh · Aug 24, 2020

alpinecrick said:
Yes, the trans has to be moved back or moved sideways to access the seal. At least yours is a 2wd.

As TBI mentioned, make sure it's not the oil pressure sender located at the back of the engine--it ain't easy to see or get to.........

Yes 2WD. forgot that tidbit. Never gave the sender a thought! Thanks for that tip!! As simple as these engines are it might be just as simple to pull the engine, IF it is in fact the rear main seal. Then I can fix my water leak at the same time. Further investigation need. AND some motivation.....

Ken

Erik the Awful · Aug 25, 2020

Motivation? You can also paint the engine while you have it out!
https://www.amazon.com/VHT-SP404-Engine-Metallic-Flake/dp/B00296IF6E

kenh · Aug 25, 2020

Erik the Awful said:
Motivation? You can also paint the engine while you have it out!
https://www.amazon.com/VHT-SP404-Engine-Metallic-Flake/dp/B00296IF6E

If I do that I would go with the classic orange!!!!! But that is just me!

Ke

delta_p · Aug 26, 2020

I just did mine. I had a wobbly harbor freight trans Jack so sliding the trans off the pins was same as moving it out of the way. Make sure you support the back of the engine when the trans comes off or she'll drop like bricks and possibly hit the distributor on the firewall.
https://www.gmt400.com/threads/oil-leak-but-not-where-i-thought-the-leak-was.48739/

kenh · Aug 26, 2020

delta_p said:
I just did mine. I had a wobbly harbor freight trans Jack so sliding the trans off the pins was same as moving it out of the way. Make sure you support the back of the engine when the trans comes off or she'll drop like bricks and possibly hit the distributor on the firewall.
https://www.gmt400.com/threads/oil-leak-but-not-where-i-thought-the-leak-was.48739/

I done a few of these, well not gmt 400's but like my 66 GTO. 45 minutes to pull the engine by myself. BUT, much less to unhook! Well aware of needing to support stuff. The pontiac would balance itself on the engine mounts, more or less. I've always made a habit of removing the distributor . It saves a lot of heartache in the long run!

Ken

thinger2 · Aug 27, 2020

I have a few different length bolts with the heads cut off and a chamfer ground on the ends.
Finger tight one into the block and use it as a guide pin.
Also works great when you need to stop for a minute or when you double check to make sure the converter is seated.
A little anti seize on the pins helps too

rear main crank seal

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