308 rear main seal leak

dave11

Soon after I got the engine back from the machine shop about 4 years ago the rear main seal started leaking, as time goes on it is progressively getting worse. I supplied the main seal to the machine shop, which he installed. The seal I sourced from one of the common Hudson engine part suppliers in OH.

I understand this is not an uncommon problem, but before I go to all the effort of pulling the engine I'd like to be confident I can put this issue to rest (I hate oil leaks !) Anyone know if there is a best practice for the install or is there a better seal on the market ?

 

Dave Eddie

Ol racer

FYI
Use the modern Neoprene Seal that Randy Maas & Dale Cooper sell by removing the oil pan and rear Cap, not the motor..

Geoff

Check also that it is actually the seal.  It could be the  string packing up the sides of the  cap is not properly installed. 

dave11

Geoff,

I tried to send you a private message, but my mail provider did not like that function.....any way the seal I provided was from Dale Cooper, one of the two piece neoprene types. I understand what you are saying about the string packing at the sides of the rear main cap. I did not install it so I cannot verify if it was done correctly or not.

So,...you can change the rear main seal in the car?? thats good news although if I recall there are 1/4" bolts securing the upper half of the seal,....are they accessable from below without removing the flywheel?

 

Dave Eddie

Geoff

 if you have the rubber seal you can change it without removing the engine or flywheel.  You cannot remove the  top cover unless you take the flywheel off, which is quite a job!  I would definitley check the side string packings before I did anything else. 

Nevada Hudson

Have the same problem, and used Bars Leaks engine stop leak, and it seems to be working.

dave11

Geoff,

What is the rubber seal you are referring to?

 

Dave

Ol racer

If they installed Dale Cooper's seal its very doubtful if thats your problem. I would Get it up on a lift or stands then inspect closely. The Pan bolts may need snugging and perhaps the oil is running back along the rail. If it appears to be rear seal area I would drop the pan (as per Motors Manual Instr) then ck the string packing in the grooves as suggested above....
Today's Mech's unfamilar with packing the main cap may not have punched enough string in the grooves. I put Black Permatex RTV (not the RTV for Gaskets though) in the groove as well as pack the string.

Geoff

I meant of course the neoprene rubber seal.  The originals were a graphite  rope type. 

lostmind

Also check the valve cover gaskets. They shrink and the oil runs to the bottom of the engine.

duncan

Also check the seal around the distributor.The oil runs to the back of the engine.   Ray

DavidC

If the majority of the oil is belching from the drain hole in the torus dust cover, then is is a bit more likely this is RMS.  If the oil is all over the place at the rear of the block, it could be coming from any of the places named above.

Walt Mordenti has thorough instructions in his Tech tips, available for purchase, or online in the HET club.  Can definitely be done with motor in car, but it's a job better done on a lift.