440 rear main seal replacement.

[MOPAR MARTY]

I know approximately 6 million threads have been created on the topic, however, I would like some fresh input. I got a 440 that has a pretty solid engine oil leak coming from the bell housing dust cover. (Yes I’ve checked valve covers and oil sending unit). I’ve also read on the previous threads that this is a common problem with the 440. Much like trying to seal a 727 transmission pan. What is the latest and greatest rear main seal to purchase that y’all would recommend? Also I plan to pull the motor. Yes I know it can be done in the vehicle but I got a engine hoist that looks lonely. Thanks for all the input. Much appreciated.

if its leaking that bad u might as well pull the motor & fhreshen it up whle u r sat it its money well sopent in the long run

 

[Mike Beaudoin]

One other thought, make sure the crankshaft is not rough or worn down. In my younger years I changed the rear main every year or so but when I pulled the engine for a rebuild and got a good look. Turns out the rope had worn down the crank shaft a bit and the crank surface was not real good and this was causing my leak. When i had the crank regound I had them build up the crank seal area and regrind to the spec for the seal. hope this helps.

 

[Barry Mugridge]

I have used a "Fast Fish" seal which is received as a completely round lip seal, you follow the directions when installing by cutting once, then installing onto the crankshaft with the cut at the top or block with a dab of silicone sealant. No leaks!

 

[Carcinogen]

While looking up info on fast fish I ran across this old post

https://www.forbbodiesonly.com/moparforum/threads/new-one-piece-rear-main-seals.89545/

 

[Clownfoot]

For me I never have offset the seal. Not that it's a bad idea. Never had need to do so. If you bolt the retainer in with no seal you will probably see that the the sides of the retainer don't appear

For me I never have offset the seal. Not that it's a bad idea. Never had need to do so. If you bolt the retainer in with no seal you will probably see that the the sides of the retainer don't appear centered in the block. For this reason I fill the sides with RTV, (I prefer Ultra Grey). You can fill the area at the back of the retainer and use a putty knife to smooth it. Also a little anerobic sealer between the retainer and block will stop any weepage. It is imperative that the seal in the cap surrounds the crank journal centered. How do we do this? Open the holes in the retainer slightly (1/32"). Now the seal will center the retainer, not the bolts. Are the oil pan bolt holes are cracked thru from using bolts that were to long? Two easy fixes. White Teflon sealer on the bolts. Or install studs with lock-tite. Fill the retainer bolt holes with RTV after installing the retainer. Not all oil pans cover the hole completely. Haven't had any rear main leaks in 30+ years of building motors. Also for what it's worth my Sons small block was leaking only under boost. It turned out the rear cam plug was cracked. We had a box of 10 Dorman plugs. Everyone in the box was cracked. Never assume.
Doug

Great instructions.I have worn knurl on crank.Any input on rope or viton seal?I used viton with it leaking before reading your thread & many others.426 wedge now out of car.Not leaking at cam plug ,galley plugs,valve covers,or oil pan.Engine oil inside scatter shield,I use red 80/90w for A833 trans ,so its from rear main.I will install new setup as per instructions & hang from hoist,just unsure of knurl & which seal. thanks

 

[dvw]

I would tend to lean towards the rope with the knurl unless you could polish the crank. Which would be next to impossible in the car. My cranks are all smooth. Maybe someone has experience with knurled cranks and the Viton seal, I don't.
Doug

 

[Clownfoot]

I would tend to lean towards the rope with the knurl unless you could polish the crank. Which would be next to impossible in the car. My cranks are all smooth. Maybe someone has experience with knurled cranks and the Viton seal, I don't.
Doug

Engine is out & crank is out.I'll check crank seal diameter & specs to see if knurl can be removed.thanks again