Rear main seal....HELP!

[Geep]

I have a leak at the rear main seal and oil pan gasket on a AMC 304 V8 . The estimate I got from a repair shop quoted over $600 for the seal and gasket replacement........says they need to drop the tranny ! iam not a mechanic by no means but that seems pretty pricey$$$. Does that sound right to you all ?????

 

[Petescj]

You do not need to remove the Transmission . The seal is 2 pieces top and bottom. The top one is a little tricky to get out sometimes but I did mine with the Transmission in. I dont know why theyd tell you that.

 

[Geep]

You do not need to remove the Transmission . The seal is 2 pieces top and bottom. The top one is a little tricky to get out sometimes but I did mine with the Transmission in. I dont know why theyd tell you that.

Thanks Pete ! Like I said, I aint no mechanic but I didnt think you would hjave to drop the tranny and $600 Plus seemed quite high

 

[Petescj]

Its a pretty basic job.
1. Drain your oil.

2. Unbolt the pan.

3. Take the two bolts out of the rear main cap.

4. Remove the bottom half of the seal from the cap.

5. Take a punch and tap the top seal till the other side sticks out enough to grab with a needle nose.

6. Work it out "gently" and install the new one.

7. Then put some RTV on the "feet" of the bottom seal after you set it in the cap.

8. Tighten your two main cap bolts to spec.

9. Put your pan back up with a new gasket and add oil.

 

[jpeck71]

Pete's right, it is a pretty basic job. Even I was able to do it and I hadn't really done anything previously besides change fluids and filters.

I suspect mine had been in there for a looooong time as it was pretty well stuck and I had to hammer on the upper half for a loooong time to get it to break free.

That was the only difficult part of the job for me. Once it finally broke free it was easy to pull it out and get the new upper half in.

There's write-ups out there with pictures that might help.

 

[Posi]

The rear main oil seal consists of a two piece neoprene single lip seal that needs to be installed correctly so it doesn’t leak. First remove the rear main bearing cap (you can see the lower seal in the cap).



I removed the lower seal and cleaned the cap of old sealer.



I loosened all the remaining bearing cap bolts and used a brass drift to tap out the upper seal enough to grab it with pliers from the opposite side.

Note: on the outer edge of the seal there is a wire (this is what I tapped on with the brass drift).



I cleaned the block seal surface and lightly oiled. I coated the block contact surface of the new upper seal with soap and the lip seal with engine oil. I then pushed the upper seal in the engine block.



I coated both sides of the new lower seal end tabs with black RTV and the outer curved surface with soap and the lip with oil. After setting the lower seal into the cap recess I put some black RTV on both chamfered edges of the cap. I also laid a bead on the block as well.



I stepped torque all the cap bolts at 50, 80, and 100 ft/lbs (AMC 360)

Hope this helps.

 

[Lumpy Grits]

Other than basic hand tools. The ONLY special tool you MUST have is a ft/lb torque wrench.
Just take your time.
Have'n a REAL, FSM(not Haynes etc)pays for itself here.
LG

 

[Geep]

Other than basic hand tools. The ONLY special tool you MUST have is a ft/lb torque wrench.
Just take your time.
Have'n a REAL, FSM(not Haynes etc)pays for itself here.
LG

After questioning the shop manager about dropping the tranny he called back and told me that it didnt have to be dropped afterall ! HmmmmAnyway, said they could do the rear main seal, new pan gasket , oil and filter for $300.......less than half of the original quote ! Youre right about the Haynes manual Lumpy. I have one and its pretty much useless. Doesnt tell nearly enough info !

 

[Posi]

You do not need to remove the Transmission .

After questioning the shop manager about dropping the tranny he called back and told me that it didnt have to be dropped afterall ! HmmmmAnyway, said they could do the rear main seal, new pan gasket , oil and filter for $300.......less than half of the original quote !

 

[Petescj]

After questioning the shop manager about dropping the tranny he called back and told me that it didnt have to be dropped afterall ! HmmmmAnyway, said they could do the rear main seal, new pan gasket , oil and filter for $300.......less than half of the original quote ! Youre right about the Haynes manual Lumpy. I have one and its pretty much useless. Doesnt tell nearly enough info !

Thats better. Id consider looking into another shop though.

Posi thanks for the pics. Thats alot clearer than the step by step I gave. It should really help the next guy who does a search on the rear main seal leak.

 

[Lumpy Grits]

How much oil are you leaking-What weight oil are you run'n?
$300.00 is still very high!
LG

 

[Neuner]

Id consider looking into another shop though.

x2!!

 

[Lumpy Grits]

How do you know for FACT, it's the RMS and NOT the pan gasket?
LG

 

[Geep]

Thats better. Id consider looking into another shop though.



Posi thanks for the pics. Thats alot clearer than the step by step I gave. It should really help the next guy who does a search on the rear main seal leak.

Thanks everybody ! I have checked with four other shops and they are all close to the same price plus or minus a few bucks ! Some say drop the tranny, some don't. This shop has done work on other vehicles of mine in the past and he was honest enough to come back and tell me that the tranny didn't have to be dropped after all. Two of the other shops insisted the tranny had to be dropped , for more money of course ! I feel comfortable with the $300 charge. At least I will know it will be done right. Me as a mechanic ?

 

[Lumpy Grits]

Have you even ck'd the pan bolts for tightness yet?
LG

 

[Geep]

Have you even ck'd the pan bolts for tightness yet?
LG

Yep they are all snug ! you can see where the gasket is cracked and sticking out at most of the bolts

 

[Petescj]

Have you even ck'd the pan bolts for tightness yet?
LG

True. We never asked if you know its the rear main for sure.

 

[Lumpy Grits]

I did ask that in post #13 with no ans from the OP
IF, you can see cracks in the pan gasket-That makes the RMS even less suspect, IMO.
LG

 

[Geep]

How do you know for FACT, it's the RMS and NOT the pan gasket?
LG

I guess I don't know for sure but the oil is building up and dripping from the end of the oil pan onto and down the inspection cover at the flywheel.
Once the oil pan is removed is there a way to tell if the rear main seal is bad ?????????????

 

[Geep]

Another thing.....I took the cj out for a putt yesterday and today and its not leaking near as bad as it was right after I changed the oil,( Mobil 10-40 high mileage ) I don't understand it