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440 rear main seal leak

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440 rear main seal leak

darins701 darins701
New User | Posts: 38 | Joined: 06/08
Posted: 05/03/09
08:19 PM

Hi guys, ready to pull my hair out on this one.....I rebuilt the 440 in my project car 2 years ago and got the car on the road last summer. In the fall it started leaking from the rear seal. Over the winter I pulled the engine to fix the leak, replace the transmission, and do a few misc things. About 5 minutes after firing it up this year it started leaking, about a drip a second. I pulled the pan and replaced the seal and pan gaskets. Fired it up again but it still leaked but not as fast as before. Thinking it could be the galley plugs or cam plug, I pulled the transmission out and crawled up under the car. I had my son run the oil pump with a drill while I watched the back of the block. Couldnt see anything seeping with oil pressure applied to it. Each time I take the seal out, I cant see anything wrong with it. I think I'm installing it right, rtv on the ends and along the seal retainer sides, seal lip facing in, etc. I know the oil level isnt too high, and it stops leaking after the engine is shut off.
Could the high volume oil pump be pushing too much oil against the seal? Could the windage tray be holding oil back around the seal? The seal area wasnt touched when the crank was reground, it still has the serations marks there. Anyone have some ideas while I wait for another seal to show up at the parts store?  

New User | Posts: 45 | Joined: 05/08
Posted: 05/09/09
04:47 PM

Hello,when you install the seal are you massaging it into place and allowing a tiny amount on the outside to nip then sealing the meeting ends and cap  

Wedgehead65 Wedgehead65
New User | Posts: 11 | Joined: 05/09
Posted: 05/09/09
09:16 PM

I feel your pain, less than 20 miles on my motor ready to pull it the 2nd time. Was checking on billet cap from 440 Source, not sure what to do. They had a tech tip, take your cap to the machine shop have them mill .010" off cap surface. They claim that will compress seal for tighter fit, and stop leaks. Let me know if you get it fixed and how, I will do the same.  Good Luck   Ernie  

New User | Posts: 7 | Joined: 10/07
Posted: 05/16/09
08:54 PM

DON'T CUT THE SEAL CAP. YOU AND THE OTHER RESPONDERS SO FAR ARE ON THE WRONG TRACK. It's more complicated than that and a long story. I;ll do my best to get back to you with some good information. DVORAK  

79redexp 79redexp
New User | Posts: 14 | Joined: 03/09
Posted: 05/17/09
07:59 AM

I have rebuilt many big block engines with no rear main leaks. Did you soak the lower retainer side seals in mineral spirits and quickly install them? Is the contact surface on the crank smooth and true with all traces of old seal material removed? Are you installing the seal lip in the right direction or mismatching them? Sometimes we get too anxious to get the job done and over look the basics. The lower seal retainer is aluminum and can warp or crack, new ones are cheap and available at most speed shops. The after market ones may be a good choice, but the factory parts work well.  

darins701 darins701
New User | Posts: 38 | Joined: 06/08
Posted: 05/17/09
08:31 AM

Well, here's an update... Tried a new seal, again, still leaks about a drop a second. replaced the high volume pump with the stock unit and thought I had it... until I got it on the highway and it started puking again. I had the seal retainer machined this weekend and reinstalled it, still leaking...even worse this time so I am going to order the billet retainer from 440 source on monday, maybe a high performance seal too.
I know the seal is installed correctly, the side seals have me a little worried but at the rate it leaks, I find it hard to believe its the side seal. Read a forum post on another site about maybe the crank was a reverse rotation crank for a boat aplication. The seal serations for them are in the opposite direction and would pull oil out of the seal. Took the pan off last night and confirmed that the crank is right.
I'm really interested in what DVORAK has to say, maybe he shed some light on this. This is starting to get expensive, $20 in pan gaskets just to drop the pan everytime.  

darins701 darins701
New User | Posts: 38 | Joined: 06/08
Posted: 05/22/09
07:01 PM I was under the car staring at it tonight and think I found the problem. The upper half of the seal is in place and it looks like the passenger  side of the seal isnt touching the crank surface. Any ideas for a fix for this? I'm thinking of putting some shim strips behind that side of the seal to hold it closer to the crank.  

drmopar drmopar
Guru | Posts: 1445 | Joined: 02/08
Posted: 05/22/09
10:01 PM

Who are you getting your seals from is the first question? If your not getting them from Mopar Performance then you are looking for trouble.
Part # from your local mopar dealer p4271961, remember to silicone in the side seals.
The lip of the seal should be facing forward. I would recommend a can of wynns engine stop leak, this product helps swell or inlarge the seal and prevents leaks after approx 300 miles of use. I put this in my 360 which developed a leak and after 100 miles the rear main leak is almost completely stopped. The motor has a constant oil pressure of 70 lbs at 3000 rpm, so this stuff really works.
Wynns #50611 engine stop leak.  
Good luck.

jerryg7 jerryg7
New User | Posts: 37 | Joined: 08/08
Posted: 12/13/09
06:34 PM

I've pretty much got the same problem.  At higher engine temp the rear main leaks about 1 drop per second.  Have you tried the Wynns by chance?  Has anyone tried the STP version of engine stop leak and know how well it works?  Will this stuff affect any other engine components negatively?
I assume there is no way of changing this seal without pulling the motor right?  I'd love to hear some suggestions!  

waynep7122 waynep7122
Enthusiast | Posts: 643 | Joined: 08/09
Posted: 12/14/09
12:26 AM

jerryg7   did you see this thread a while back????

somewhere in the middle of the thread  there are also some links to other magazines on this site about installing rope seals properly...  

.71RedneckStroker_ .71RedneckStroker_
Guru | Posts: 848 | Joined: 11/09
Posted: 12/14/09
05:35 AM

Since you did bring up the oil pump......if  you have a stock cpcacity pan, there's absolutely no need for a high volume oil pump. WHether that'll solve your leak is another guess. I found this horror story with a quick Google search.  

I can put a square peg in a round hole. Gimmie that hammer.

darins701 darins701
New User | Posts: 38 | Joined: 06/08
Posted: 12/14/09
07:54 PM

Oh sorry, I forgot to post a final update...
Well, long story short, the rubber rear main seal was not touching the crankshaft on the passenger side of the block, and really tight against it on the driver side. Tried to make something work with the rubber seal and sealer, shims, etc, but nothing I was happy with. I was about to tear it all down and remachine the block to realign the seal grove with the crankshaft centerline, but the machinist said to try a rope seal first. That fixed it. The rope seal will flex and move to fit around the crank and provide a positive seal. Bill said I may see a drip every now and then, but so far, so good.

Now one thing to make note of here.....After a few tries with the rubber seal, I bought the billet rear seal retainer from 440 source. This compounded my troubles as the billet one did not have enough material milled from the engine side of it to allow oil from the back of #5 bearing to drain back to the pan. It was holding oil, and some pressure, against the rear main seal, making the leak worse. When the billet retainer and #5 bearing retainer were bolted in the block, there was almost no clearance between them for the oil to escape the back of the bearing, it was staying up against the seal. I had it machined to look like the factory retainer, and it worked great after that. If you compare them side by side, you will see what I mean. The factory piece is undercut for oil drainage, the 440 source one is not.

There is another post around here that I pretty much say the same things in, and he had the same problem I did. He ended up putting in a rope seal and it worked for him too.I would NOT put stopleak in a new engine. In a new engine, you shouldnt need to "soften" the seals. If your new seals leak, you have other issues that stopleak isnt going to cure. It may work in older, high mileage engines, and I would try it in a pinch, but thats really off topic for this post. Thanks for reading....  

dnelson dnelson
New User | Posts: 2 | Joined: 08/13
Posted: 08/03/13
04:48 PM

Is there a way to replace the rear seal on a 440 without pulling the engine?  

waynep712222 waynep712222
User | Posts: 127 | Joined: 04/13
Posted: 08/04/13
05:29 AM

Icon Quotednelson:
Is there a way to replace the rear seal on a 440 without pulling the engine?

perhaps this will help

There are some variable's with this operation so I will try to explain. Ok there are two different types of seals that you may run into in a 440. The factory seal was made out of what looks like rope. These are called rope seals, not to surprising. These seals are a soft textile like a rope, impregnated with super thick wax, and graphite. These seals work well, and have been around for the last hundred years. The other type of seal is a later invention and it is a rubber seal, split into two different halves. The seals have to be split because the crank has a big flange on the rear and you cant slide a seal on from the rear. So all 440 seals are two piece. The 440 uses a seal retainer to hold the bottom half of the seal, and it is attached with two 12 point bolts. The top half of the seal is mounted in a groove in the block. Check out the two photos below. You can see the seal in the block, and then you can see the lower seal retainer installed. The seal in the pics are the newer rubber style seal.

Now both styles of rear seals require you to drop the oil pan to change the seal out, there is no need to remove the transmission. There is a catch here. If you have the original type of rope seal it can be exceedingly hard to change out. The bottom half easily comes out of the seal retainer, once you remove the oil pan, and remove the lower seal retainer. The problem is the top half of the seal that is in the block often breaks into little pieces when you try to remove it. This makes it virtually impossible to remove with the crankshaft installed. If you get to this point, and run into this, the work required to repair this can require the engine to be removed and disassembled far enough to remove the crank. This is worst case scenario. Most of the time an experienced 440 mechanic can drop the main bearing caps and pull the crank ever so slightly down, and then remove the remnants of the seal.

So how much time does it take? That remains to be seen, because we don't know what we are looking at in regard to the seal type. Minimum of 4 hours is what I would count on for labor. It could also get up to 20 hours if the engine was to have to be removed to replace a stuck rope seal, this is the worst case scenario.. Expect the parts to cost about $50 to $90.

dnelson dnelson
New User | Posts: 2 | Joined: 08/13
Posted: 08/04/13
09:24 AM

I have the rubber seal. I just fired the engine up [rebuilt] and leaks quite a bit.The bottom seal is easy enough but any suggestions on getting the top out?.Thanks  

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