383 Rear main Seal leak

[69 Soop R Bee]

I know, this topic has got to be the most beaten to death problem. Please bear with me, I have searched for hours and read all I can read.

383 Stock Crank. Oil Grooves (knurling) still present and dial indicator shows 0.002 runout tops on seal area of crank.

Using Manicini Billet Retainer - upon inspection the top corners are beveled slightly and do leak if installed without any type of sealant. (top reference = motor upright)

I am using the Felpro Main seal sold by everyone and their mother.

When I put the top half of the seal in the motor I have tried putting a smear of silicone on its backside before the crank was installed. Same for the oil seal in the retainer. Just enough silicone to provide a barrier if oil tried to seep past it.

On the retainer with the end seals installed, I put silicone in the top corners and smeared silicone on the top face of the retainer where it clamps against the block. I did also smear the tiniest amount on the seal where the halves mate. I made very sure there wasnt enough to get on the crank or on the lip.

Rear seal doesnt appear to leak at idle but when driven it leaks and I see a drop or two in the garage. I pulled the motor and noticed oil on the frame rail and headers right across from the flywheel.

Motor doesnt have a PCV valve, I have 2 -10 AN lines running to a -10 T which goes into a STEF Catch Can breather. The 2 -10 lines i have Y into 1 -10AN fitting right at the catch can. Motor only has 600 miles on it so I am second guessing a crank pressure issue here.

Oil pump is the melling HIGH Pressure Pump......Mancini tells me this is a problem if I am running a stock oil pan and possibly the problem.

What am I doing wrong here or what can i do to solve this issue? as it is i never bring the car out the garage becuase i dont want the hassel of having to wipe oil off everything and I am tired of that. Its terrible this 3 year restoration cant be driven.

Terry

[69 Soop R Bee]

Good friend pointed me in a good direction......it was a direction I was avoiding accepting. With good guidance I learned something very valuable for the next motor build.

I measured the amount of compression on the lower seal in the retainer. This would be an issue if Line bored. So I pulled out both seal retainers, Mopar and Mancini......I get less that adequate of compression of the seal.

Rail to Crank seal area: 2.359 (1" straight edge)
Mancini Retainer sits .008 higher than rail
Mancini Rail edge to Seal lip 2.375
Math: 2.375-.008-2.359=.008 compression

Mopar retainer sits perfect flush with rail
Mopar rail to seal: 2.364
Math: 2.364-2.359 = .005 compression

I am informed by my friend that .010 compression is minimum for a leak free seal.

The mopar retainer was in when i bought the car 10 years ago and the car always leaked in the rear main area......now we can see why.

Hopefully taking .010 off the retainer and seal edge will solve this. That will make the retainer sit nice and pretty with the oil pan rail and give me .018 compression on lower seal lip.

Terry

[chirorod]

I'm thinking that the bead of silicone is what is limiting the seal compression.

[69 Soop R Bee]

these measurements are all takes with the surfaces clean and free of any silicone so no thats not it.

[John Kunkel]

Originally Posted by 69 Soop R Bee

Oil pump is the melling HIGH Pressure Pump......Mancini tells me this is a problem if I am running a stock oil pan and possibly the problem.

I fail to see the reasoning there, what difference would the oil pan make?

I completely gave up on using the neoprene seal with a knurled crank, the rope seal worked for years so why fix something that ain't broke.

[nhdriver]

I had a similar problem w/ rear main seals on a 440 I had built. After changing it once w/ a new rubber one it still leaked. I tracked down an old "rope" seal & it ended the leak. I don't know if he old school rope seals are available anywhere. but I'd try one & see if it solves your leaking problem.

[JVMopar]

Why not run a PCV valve?

I think your whole problem is crankcase ventilation. Unless your putting the seal in backwards or something.

[dodger1]

Originally Posted by JVMopar

Why not run a PCV valve?

I think your whole problem is crankcase ventilation.

I was wondering the same thing - PCV systems don't hurt performance one way or another AFIK. JK and nhdriver might be on to something regarding the old-style rope seal too.

[69 Soop R Bee]

I agree that the high pressure pummp does not make sense. I gave the concept consideration becuase I read some info in various places on the net where people had high pressure and dropping it solved the issue.

I dont run a PCV because of Break in and I dont want blowby during the process entering my intake (intake style PCV).....depending on the levels, burning oil vapor does hurt performance from simple mixture issues to increasing preignition. I can install a PCV in the exhaust system if needed. With the -10an lines I couldnt imagine there is pressure in the motor but who knows unless I put a gauge on the dipstick tube.

I am going to add a PCV to my intake and try it, If I notice oil residue I will have to weld up an alum catch tank to put inline with the PCV valve. I could make a slender one to tuck under the Indy intake if I need to. It would just take a lot of finesse with all the alum baffles that would be needed.

Right now I am suspecting the seal is the issue as well as crankcase pressure. With the seal halves clearly misaligned by 1/8" and the lack of pressure on the lower seal area, this makes so far makes sense. You cant argue measurements and numbers, if you could then why bother building to specs. I also upgraded the seal to Viton material. I offset the seal by 3/16" to make sure the alignment is proper and the retainer has been milled. Everything went back together last night and hopefully I will get it back into the car by Friday and ready to fire. If not then it will wait till Jan 5th since I head to Florida.

If this doesnt work the Rope seal may be the best bet but I would have to source out a mopar retainer since the Billet ones dont have the nubs to keep the seal from spinning/moving. I dont have much experience with rope seals so that too will factor into my issues. I am concerned about the amount of drag that the rope applies to the crank. I have been read that people have done dyno tests and seen as much as a 10hp loss. I agree with running factory seals if they worked but they didnt, rope seals never stopped seeping and every so often you need to degrease the area. I know, it beats oil on my frame, I am not arguing that it is better than what i have now. So many people have had great luck with neoprene so I dont see why I cant make this work.

I have a couple design ideas for a single piece Main but until I have a couple million to do the R&D......I am shit out of luck

Terry

[dodger1]

Regarding the comments on a "high-pressure" oil pump, I recall getting advice back in the late 90's when I was putting my mild 360 together. The advice generally said to go for a "high-volume" pump vs. an H.P. type. Melling offered both, I went with the high-volume unit. No issues for 13 years now (except for an improperly balanced crank that destroyed the rear main after 20,000 miles)

[John Kunkel]

The HV pump has the HP spring so it's high pressure also.

I don't buy the notion that high oil pressure affects the seal, there is a slinger between the bearing and the seal so that pressurized oil escaping the rear bearing can't apply pressure directly to and overload the seal.

I do, however, agree that crankcase pressure effects the rear seal's ability to hold back oil

[dodger1]

[QUOTE=John Kunkel;824171]The HV pump has the HP spring so it's high pressure also./QUOTE]

Now you tell me. Never heard that before. Curious as to just what does differintiate the two?

[rlaman821]

As soon as you guys figure this out let me know. I'm having the same problem with my 440. I just figured it was due to the track time it sees.

[JVMopar]

Originally Posted by dodger1

Now you tell me. Never heard that before. Curious as to just what does differintiate the two?

The high volume pump has a gear that is taller than a standard pump.

A high pressure pump has a stronger relief valve spring.

Here is a video by melling explaining the differences in detail. http://www.youtube.com/watch?v=tOiHd...layer_embedded

[dodger1]

Thanks jv. Actually an oil pump is pretty simple - I should have figured out my own question! I notice the HP spring allows 75-80 psi in the std pump, but only 70 psi in the h.v. unit. A function of volume only? (Sorry, I'm hijacking this thread!)

[JVMopar]

Both pumps should create the same pressure IF they use the same high pressure spring compressed to the same installed height. Assuming of course the bearing clearences aren't too large for the standard volume pump to make maximum pressure.

Pressure is created by the restriction of flow. So if you have the same restriction but more flow (higher volume) then the pressure will be higher. The relief valve in the pump is what regulates the pressure. So the pumps must either use a different spring, or have a different installed height for the high volume pump to have a pressure set to a lower max psi.

Here's another video that explains volume (flow) vs pressure. http://www.youtube.com/watch?v=7IpJl...Co3pLbMfnOv-B-

[rlaman821]

So let me break in here a sec. I had the crank turnend .010. Should I have tightened up on my retainer also?

[JVMopar]

When they grind the crank they don't grind the seal surface. Otherwise you'd have to have an oversized seal to fit the crank. They probably polish the seal surface with some fine emery cloth.

[rlaman821]

Ok JV, that makes sense. I was going to say I never had to tweek the rear seal on any other crank. But that brings us back to the original question. How do I stop the rear main seal leak. I have the pcv vented to the atmosphere. Is it enough for a street/strip car? I want to replace the seal this winter as soon as time allows but I was just going to clean it up real well and do it over. I don't think the oil pump has anything to do with it myself. I was leaning to too much crank pressure. The car does not lead a pampered life but the motor is only a year old so it shouldn't be leaking already.

[John Kunkel]

Originally Posted by JVMopar

So the pumps must either use a different spring, or have a different installed height for the high volume pump to have a pressure set to a lower max psi.

I have had both pumps apart side-by-side and the spring is the same for the HP and HV pumps...in fact, the pump cover with the relief valve is identical on both, the only thing that makes them different is the main housing and wider rotors.

[69 Soop R Bee]

RLAMANN, what has probably happened in my case is the mains were line bored. Anytime you do that there is a possability the crank now sites higher (towards the cam). That is why my lower seal fits looser than it should.

If you have an original block and are not the original owner you have no idea if that was ever done to that motor. Only way is to measure. You would need to pull the crank and reference everything off a straight edge across the oil pan rails. I have talked with 2 shops once (both i know the owners) and the agreed if a motor comes back with a rear main they cant seal, that is how they would go about verifying the seal contact pressure.

Another thing you need to do is bolt the retainer in with the crank out and check how the ends of the seal line up. Mine was sitting too far back if you just simply put it in and didnt check. I ended up rotating my seals 10* so they would line themselves up. I just had to make sure the retainer was square.

I have mine back in the car but I have a blown PV in the carb so i have to wait till after the holidays to get one. I leave for florida in 3 days so i wont get back to this until Jan 4th. Considering I have identified 2 issues, I am confident this will solve my problem.

With the concept of the Rope seal being factory.....I was looking at the factory service manual for shits and giggles and it never mentions setting up a rope seal, it describes the installation of a Neoprene..........Found that interesting

Terry

[John Kunkel]

What year is your FSM? Anything earlier than the mid-seventies covers the installation of the rope seal.

[69 Soop R Bee]

You know what, your right John. It does mention cutting the seal after you use CXXX tool to install it. You really cant cut a neoprene. I didnt pay close enough attention to the last step last time I browsed through it. It doesnt mention anything about using any sealant though.

I did find a TSB from 1971 online when the Neoprene came out and was directed to be installed on any 426 with rear main leaks. might have been on this site i saw the TSB too.

[chirorod]

When I was working at Volvo, the dealership added Nissan (Datsun then). They sold a Datsun B210. The rear main seal leaked. That one was a one piece seal. It was changed 3 times, each time by a different one of the techs. It never did get solved, so Nissan authorized an engine change. I hope that isn't the only way to fix your problem.