Procedure - Engine Removal, Rear Main Seal Replacement

[Great Pumpkin]

Hi, just getting into car I bought in fall and have a couple of questions regarding a leaking rear main seal. I was looking at Service Manual engine removal procedures, says to remove transmission - really necessary (no lift, dirt driveway)? Anyone have a written procedure for replacing 318ci (Fury) rear main seal? Advice for what else to replace while engine is out? I'm not the most (maybe the least) mechanically inclined but will round up friends to help. Really appreciate it, Bob

 

[65sporty]

If all your changing is the rear main it can be changed while the engine is in the car.

 

[Davea Lux]

Hi, just getting into car I bought in fall and have a couple of questions regarding a leaking rear main seal. I was looking at Service Manual engine removal procedures, says to remove transmission - really necessary (no lift, dirt driveway)? Anyone have a written procedure for replacing 318ci (Fury) rear main seal? Advice for what else to replace while engine is out? I'm not the most (maybe the least) mechanically inclined but will round up friends to help. Really appreciate it, Bob

The rear main seal can be replaced with the engine still in the car as noted above. You can drain and remove the oil pan. You may have to unbolt the idler arm on the steering linkage and unbolt the motor mounts to jack up the engine in order to get the pan to clear. Be careful doing this so that you do not damage the fan shroud if the car has one. You should also remove the starter to get it out of the way; if this is a single exhaust car, the cross over pipe will also have to be removed. Once that is done, You can remove the rear main cap. Inspect the bearing, if there is copper showing, the bearing is worn out and the engine will probably need to come out for a rebuild. If the bearing appears intact, you should then check it for excessive clearance using a plasti-gauge. If the bearing clearance is within specs, you then can consider replacing the main seal. Several manufacturers sell a kit to do this and the FSM goes into detail on how to do it properly. I would also recommend replacing the timing chain at this time, and it would be a good idea to check the rest of the main bearings and rod bearings while the car is apart. If this car has 100k or more miles on it you are probably headed for a rebuild.

Dave

 

[livininharrow]

Hi, just getting into car I bought in fall and have a couple of questions regarding a leaking rear main seal. I was looking at Service Manual engine removal procedures, says to remove transmission - really necessary (no lift, dirt driveway)? Anyone have a written procedure for replacing 318ci (Fury) rear main seal? Advice for what else to replace while engine is out? I'm not the most (maybe the least) mechanically inclined but will round up friends to help. Really appreciate it, Bob

how bad is it leaking? if its not that bad then try lucas oil treatment. it may help. if the leak is excessive than you will have to most likely pull the motor with some help from your friends. good luck. if its a small leak then leave it be. oil is still cheap the last time i checked.

 

[Zwap]

The rear main seal can be replaced with the engine still in the car as noted above. You can drain and remove the oil pan. You may have to unbolt the idler arm on the steering linkage and unbolt the motor mounts to jack up the engine in order to get the pan to clear. Be careful doing this so that you do not damage the fan shroud if the car has one. You should also remove the starter to get it out of the way; if this is a single exhaust car, the cross over pipe will also have to be removed. Once that is done, You can remove the rear main cap. Inspect the bearing, if there is copper showing, the bearing is worn out and the engine will probably need to come out for a rebuild. If the bearing appears intact, you should then check it for excessive clearance using a plasti-gauge. If the bearing clearance is within specs, you then can consider replacing the main seal. Several manufacturers sell a kit to do this and the FSM goes into detail on how to do it properly. I would also recommend replacing the timing chain at this time, and it would be a good idea to check the rest of the main bearings and rod bearings while the car is apart. If this car has 100k or more miles on it you are probably headed for a rebuild.

Dave

If you don't see any copper on the main bearing, just replace the seal and drive away and look happy

 

[Great Pumpkin]

The car has 21k on it and the leak is...maybe a ounce or two in five minutes. i have read the merits on rear main seal replacement with both engine removed and in the car, and am having a hard time figuring it out. Thanks for your replies. Dave, or anyone else, have an estimate on number of hours to replace without engine removal? Or any reasons not to attempt this while engine is in the car?

 

[Davea Lux]

The car has 21k on it and the leak is...maybe a ounce or two in five minutes. i have read the merits on rear main seal replacement with both engine removed and in the car, and am having a hard time figuring it out. Thanks for your replies. Dave, or anyone else, have an estimate on number of hours to replace without engine removal? Or any reasons not to attempt this while engine is in the car?

It much easier with the engine out. I do not know your skill level, but this is a job for somebody who knows what they are doing. If you have skilled friends go for it. The main thing to remember is that improperly done, you could wind up with a spun rear main and a ruined engine.

Dave

 

[65sporty]

The time to change the seal is going to depend on your skill level. If I was doing it probably a few hours but I have access to a hoist and have done many rear mains in many types of cars and trucks

 

[LeBaron1973]

You'll save lots of time if it can be done insitu, so try that first, you can always remove the engine if needs be.

 

[Great Pumpkin]

I did look and looked again in the Plymouth factory service manual for the procedure, cant find it. I imagine it'd be in 318 engine section...

 

[Big_John]

OK, I'm gonna ask the question since nobody else has...

Are you sure it's the rear seal? The oil pressure sender can leak, oil dribble down the bellhousing and mimic a rear seal leak.

Changing the rear seal in the car with the trans in place can be done. I've never done one myself in the car, so I can't give specifics, but it's basically pull the old seal out and roll the new one in. A lot of things have to go right and it's not any fun doing this on your back in the dirt. Honestly, I think you might want to find someone to do this job. In the long run, you might be time and money ahead.

Still... check out the sender first.... I've seen them leak a lot more times than having a rear main seal fail.

These guys are rude and crude, but it shows the removal of a main seal in a 318. You may have a rope seal there now, but it will give you an idea.


NWS for language.



Stumbled on this too... Illustrates what I was saying about the sender being the issue.

 

[Big_John]

And along with the oil sender... Oil pan gaskets and even valve cover gasket leaks can look like a rear main leak...

 

[Big_John]

This is on a Jeep, but it shows the method pretty well.

 

[70bigblockdodge]

Could also be cam plug or oil gallery plugs but usually only if engine has been apart. Replacement cam plugs on a small block are P.O.S to start with. Disregard if you think it is really 21k.

 

[imperialman]

Thanks everyone for the information even though I am not the original poster. I have been procrastinating on replacing the leaking rear main seal on my 78 NYB.
Luckily? a Minnesota winter intervened with my planned replacement and the car went into storage.
I would assume that most the information here would also apply to my New Yorker?

 

[Big_John]

Thanks everyone for the information even though I am not the original poster. I have been procrastinating on replacing the leaking rear main seal on my 78 NYB.
Luckily? a Minnesota winter intervened with my planned replacement and the car went into storage.
I would assume that most the information here would also apply to my New Yorker?

You don't have to pull the main bearing cap in a big block.... But again, make sure it's not the oil sender etc. before you start the job.

 

[imperialman]

You don't have to pull the main bearing cap in a big block.... But again, make sure it's not the oil sender etc. before you start the job.

Thanks I will. The rest of the engine (400) is bone dry and I looked it over carefully when first contemplating replacing the seal.
Believe me I will look it over carefully again before tearing into it .

 

[celticwarlock]

You don't have to pull the main bearing cap in a big block.... But again, make sure it's not the oil sender etc. before you start the job.

If I can jump in here...my 440 has the same issue. You don't have to pull the main cap to replace the rear main seal? Is the seal held in by the pan only? If that's the case, I'm absolutely leaving the motor where it is when I replace it.

 

[Big_John]

If I can jump in here...my 440 has the same issue. You don't have to pull the main cap to replace the rear main seal? Is the seal held in by the pan only? If that's the case, I'm absolutely leaving the motor where it is when I replace it.

The big block rear seal is held in by an aluminum retainer that looks like this. Small block is held in by rear main cap.

Consult your FSM for more info.

And again... Check the oil pressure sender etc. first.

 

[moper]

Hi, just getting into car I bought in fall and have a couple of questions regarding a leaking rear main seal. I was looking at Service Manual engine removal procedures, says to remove transmission - really necessary (no lift, dirt driveway)? Anyone have a written procedure for replacing 318ci (Fury) rear main seal? Advice for what else to replace while engine is out? I'm not the most (maybe the least) mechanically inclined but will round up friends to help. Really appreciate it, Bob

As was said - check of other sources of oil. That sounds like an oddly fast rear main, even with 100K miles... I'd look more at the oil pressure sender, or the rear of the intake manifold before you think of doing the rear main seal.