Oil leakage Rear seal 440 engine

[1971 chrysler 300]

Hi guys,

Could you please take a few minutes and help us out here. It's about my '71 Chrysler Three Hundred, with a standard 440 V8. We've been working on fixing a problem for so long now, and we're at a point right now that we're realy stuck and desperate.

This is the story of a real nasty oil leakage. It all began one day, cold start and oil immediately soaked out of the back of the engine. A coffee cup would be filled in like five or ten seconds. It has never leaked there before. We could see that it was engine oil. So we removed the tranny to be able look at the rear main seal. We were not able to start her and do some extra inspection when it was removed, because the starter spins the torque converter which is attached to the tranny. So we were unable to start it while the transmission was removed. We removed the aluminum rear main seal cap and the seal itself (two halves).

Then we installed a new seal kit according to specs (lip toward block) and installed a new aluminum seal cap and side seals in the cap. Then we installed the pan, the tranny, everything including fresh oil. We fired her up again: same problem. Oil pooring all over the floor. It just came out of the new rear main seal again.

We thought we could have made a mistake while installing the new seal, so we took everything apart again. Installed a new seal again, but this time, we manually built up oil pressure (by spinning the oil pump with a tool). Again, oil came out of the back of the rear seal.

Then we took the whole engine out (while it was out, we also replaced some gaskets, like the one for the intake) and again installed a new rear main seal. This time we used some silicone on the outside of the seal halves, thinking that would do the trick.

Installed the engine and tranny again. What do you think? Floor still gets wet in 10 seconds. We checked the oil pressure. Cold start and it climbs to 60 psi (idle). Rev it up and it gets to 72 psi. We've checked this with some websites and this seems to be pretty good for
these engines. It also runs like a dream. Starts right up and no weird noises.....the only thing is that it still leaks like hell. Another thing that might be a bit peculiar, is that the pressure climbs to 60 and when you rev the engine, it crawls to 72, once it idles again, it crawls back down to 60. Shouldn't the oil pressure indicator react on rpm's immediately?

As you probably can imagine, we're pretty stuck and depending on help from others. A local USA car garage (we're in Holland) wouldn't even want to look at it, affraid he couldn't repair it, because we replaced the rear main seal for three or four times now. The problem doesn't seem to be the rear main seal. What can be causing such an excessive leakage out of the rear main seal?

Any tips would be greatly appreciated. Thank you very much in advance.

Best regards, Luc & Niels

[Chatt69chgr]

It doesn't sound like the seal itself has failed.  It sounds more like there is excessive pressure inside the crankcase forcing oil through the seal.  I'am thinking that a bad PCV valve would cause this.  Also, there is a spring in the oil pump that regulates the oil pressure to the mains, etc.  But usually a stronger spring is used to increase the oil pressure.  I suppose some debris could have lodged in the oil pump somehow and maybe could mimic a stronger spring.  If the fuel pump diaphram failed it could allow raw gasoline to mix with the oil thereby decreasing the viscosity.  I don't know if this could account for the oil leakage out the rear seal but probably would quickly cause bearing failure.  Obviously, I'am guessing.
I'll be interested to hear what the real experts on here have to say.

[Just 6T9 CHGR]

Stupid question.....you're sure its not coming from the oil gallery plugs in the back of the block correct?

have you tried milling down the seal retainer a few thousands to get a better seal on the crank itself?  Did you try the original style rope seal or have you been using the rubber type?

[1971 chrysler 300]

Hi,

I'm very sure that the oil is leaking through the seal. The gallery plugs were reinstalled with new lock-tite. I'm using new rubber seals. The original rope seal type isn't in the market any more, is it? I find it also a bit strage that the tolerances in the sealing are so little. I mean, there's so less between a leak and no leak at all. I have tightened the bolts from the retainer at 28 lbs as prescribed in the manual. I was also thinking that the force on the lower half of the seal meeting surface is pushing so hard against the upper half that he's pussing it away from the crank surface,just like you said. Anyway, thanks a lot for your thinking! Any help is still welcome.

Best regards

Niels

[srpntlair1]

The original style rope seal can be bought from Victor part number JV551 good luck and check for back pressure as stated

[Rolling_Thunder]

just to clarify - you have owned this vehicle for a while and it just started doing this ? 

The only time I have seen that bad of an oil leak is when a marine crankshaft is used... 

[firefighter3931]

Here's a good thread on rear main leaks and how to correct the problem. 

http://www.dodgecharger.com/forum/index.php/topic,35697.0.html



Ron

[Steve P.]

That sounds like allot of oil in a short time to me. Not to sound like a smart ass, but are you sure it's coming from the rear main seal and not the oil pressure sending unit? That could easily fill a cup in 10 seconds.

[1971 chrysler 300]

Thank you Ron in the first place. I'll check if it will help. Seems like i'm not the only one thats getting a bad headache from that leak

Oh and, the oil pressure sending unit is not leaking for certain! I'm sure it's coming out te main seal, but thanks for thinking with me.

BR,

Niels

[ITSA426]

I've heard of this happening if your crankshaft is still knurled for the rope seal and you are using a neoprene rear seal.  The local shop here takes the knurling out when grinding crankshafts because the rope seals are almost never used anymore.

[idahogrumpy]

Hi, could your problem be that the seals are to long and butting up hard causing distortion at the parting line? Or if the seal appears not to have enough crush, you might try a thin amount of silicone behind the seals where they lay into the block and retainer. Let it dry and then install. I also rotate the seals so that the parting lines are in the block and seal retainer, with just dab of silicone at the parting lines. Have you tried another seal retainer?  Good luck Kyle

[Chatt69chgr]

Am I hearing that if you don't use the rope seal but use the neoprene seal that you should have the knurling removed?  If so, thats the first time I have heard of that.

[Sublime/Sixpack]

Me too.

[Chatt69chgr]

I talked to Hughes Engines today and they told me that their rear seal has a "accordian" piece that helps the side seals seal properly.  They said the old Mopar Seals had asbestos in them that supposedly swelled up after immersion in oil and so developed a better seal.  Of course, the rubber isn't going to do that.  They also mentioned the alignment issue with the main seal.  Their seal kit comes with some instructions on how to install the main seal.  I bet these instructions were the same ones that were detailed on here in another post.  They did say that some aftermarket crankshafts come without the knurling.  Would be nice to hear from a big shop like Ray Barton or someone like that on the rear main seal issue, whether and when the knurling is needed, and why.  Do you think knurling was needed with the rope seal but maybe not with the rubber seal.  I don't think any other surfaces in the engine that have seals have knurling on them do they? 

[1971 chrysler 300]

I'm for sure that my crank isn'st knurled. So if the car used to have a rope seal with a knurled crank in its early years, there must have been a crank change during the cars' life. However, the initial broken seal was also a rubber one so a new rubber one should do I thought! But haven't been able to fix it eversince. I'm bringing the engine to a guy with a mopar shop next week. We'll keep in touch!

BR,

Niels