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athawk11
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Oil Pressure and Rear Main Seal
09/05/18 at 12:51:32
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Thought I would run this by the 3A team to see what you think.

I love my green Willys, but it had two flaws. The TC whined like a 5 year old at bedtime.  And number two, Iíve never been able to solve my rear main seal leak.

I rebuilt a replacement TC this past spring.  I upgraded to a TC with a 1-1/4Ē intermediate shaft.  This case runs much quieter at high speeds, so now Iím down to the rear main seal leak. This drives me nuts.  Those of you that know me personally understand why I donít like this.  For those of you who donít know me, Iím the guy that scrubs my undercarriage after a week of Willys trail adventures.
 
This is a GPW engine.  Tolerances in that era were not as precise as they were during later 3A production, so Iím already fighting an uphill battle.   Short of pulling the crankshaft and having this race repaired, I have tried every conceivable approach to eliminate this flaw.  I have installed 5 different seals and used just as many different techniques. Nothing stops the leak.

What I have noticed over the years is the rear main wonít leak unless I push the engine to its extremes.  The oil pressure on this engine is around 23psi at warm idle and mid 50s during warm acceleration.  It's much higher during warmup. (40psi at cold idle)  This is pretty high for an engine like this.  I believe this high pressure pushes the oil out of the weakest point.  In my case, the rear main seal.

I am considering putting a weaker relief spring in the oil pump so to reduce the overall engine oil pressure. I knowÖcrazyÖright?  We are always trying for higher oil pressure.  My thinking is this would possibly reduce the pressure on the rear main seal and thus reduce my oil loss.  Or am I thinking about that relief spring in the wrong way?  What do you think?
   
This is a photo of one attempt to stop the leak.  In this case, I compressed the filler dowels  and let them set up in a bath of RTV sealant for a few days.  The blue you see is what squished out when I compressed the dowels.




  

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1-1946 CJ2A
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mtnman37879
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Re: Oil Pressure and Rear Main Seal
Reply #1 - 09/05/18 at 13:48:53
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How do you intend on stopping the undercarriage rust If you clog up the anti-rust spray?
  

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Trust me, It's not out of my way at all.
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stony
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Re: Oil Pressure and Rear Main Seal
Reply #2 - 09/05/18 at 14:44:22
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IMO messing with the pump is a bad idea.† If your finger is bleeding there are two ways to stop it, put on a Band Aid, or stop the heart, pick one Wink.† If you changed the seal five times, then the problem is probably not the seal.† Couple of thoughts, it might not be the seal, there could be some flaw in the block and it is leaking under the seal, or it might be that the crankshaft under the seal is not exactly round and may leak under high pressure, especially with a rope seal.† If you take the cap off again you might want to put a dial indicator on it.† I guess, if you can, try to determine the exact location of the leak.† Me, Iíd just buy a bag of oil dry Cheesy
« Last Edit: 09/05/18 at 14:50:04 by stony »  

Terry
1949 CJ3A† 11159† †body 11225 engine 11140
On preservation vs. restoration:† Roscoe Lee Brown "the Cowboys" when he met the whores on the trail:† "Well, I have the inclination, maturity, and the wherewithall... but unfortunately I don't have the time."
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specialty
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Re: Oil Pressure and Rear Main Seal
Reply #3 - 09/05/18 at 15:18:22
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I have done mine twice now Tim and still have a few drips but nothing serious. Never tried the rope though. I forget where the last seal came from but it's much better than the first one. Also my crank had some pitting but i took care of that the last time. Just how bad does it leak?
  
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64CJ5
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Re: Oil Pressure and Rear Main Seal
Reply #4 - 09/05/18 at 21:32:02
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Hay Tim,  Looking forward to seeing you at the FCT.  On Eeyore the CJ5 the oil pressure went down and the oil was flowing out around the rear main.  I took things apart and there was no rope seal.  The rope had plugged up the screen on the oil pickup.  I put in the neoprene/rubber seal and cleaned the screen.  Things have been good on the oil side since then.
I do not think I would put in another rope seal.
  

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Gunslinger
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Re: Oil Pressure and Rear Main Seal
Reply #5 - 09/06/18 at 08:46:49
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Hi Tim,
Looking forward to meeting you and the rest of the guys at FTC as well.  I'm going to weigh in here on the leak as well.  Please don't mess with the pump.  As you guys know I changed my lube system on Triple X to a full flow pressure system, I get 50-60 PSI on a warm engine consistently with 30 weight oil and I'm not getting any leakage past the crank seal.  On my last rebuild we put in a neoprene seal and it seems to be working fine.  I will caution everyone though to be careful with these as well, my first neoprene seal from Felpro disintegrated in about 5 minutes and cost me another crank...

If  you do want to relieve some pressure in the engine another thought would be to enlarge the pilot hole that provides lube to the timing gear/chain.  When I put mine in we actually closed that hole down to 12/1000. If I remember correctly the original on the L134 was 70/1000, but there were issues with the front crank bearing failing from lube problems, so willys changed that to 35/1000 to solve the problem.  Like I said on my last rebuild we went to 12/1000, and that really pushed my OP up.  Just a thought, but I think I'd work the seal issue first.  Beware the unintended consequences.
  

Climbs trees, hides in the long grass, hangs out with wet dogs...
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aboyandhisdog
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Re: Oil Pressure and Rear Main Seal
Reply #6 - 09/06/18 at 11:09:11
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Gunslinger wrote on 09/06/18 at 08:46:49:
my first neoprene seal from Felpro disintegrated in about 5 minutes and cost me another crank...



What do you mean here?  I thought Fel-Pro made good stuff.  Are you saying all your oil ran out and the crank was destroyed...what about the rest of the engine?  So, what brand seal did you end up with?  Inquiring minds want to know - we need more information. Huh
  

Tom

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specialty
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Re: Oil Pressure and Rear Main Seal
Reply #7 - 09/06/18 at 15:34:39
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My first neoprene seal worked great for about 20 miles. Then the oil would almost run out when hot. Some of the seals were made wrong from what I understand and would groove the crank or just fall apart. I found a man that had the right ones but can't recall his name. It performs well. Just a few drips now and then.
  
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athawk11
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Re: Oil Pressure and Rear Main Seal
Reply #8 - 09/06/18 at 21:55:28
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Mtn, I coated every inch of this Willys with Master Series Silver.† 7 years later and no rust.† None.† I do touch up rock chips...and I live in a dry climate.† All contribute to the lack of rust. So, no need for a coat of protective oil on this one.†

Stony, The tolerance of the rear main seal race is not perfect.† This is why I no longer try the neoprene seals.† Again, this era of engines were built quickly and put into service.† Estimated average survival rate for the WWII jeep was something like 2 months, so a leaky rear main seal on a new engine was not much of a priority at the time.

Specialty, After a 40 minute trip at 30-35 MPH, it will create about a 1" spot.† After a 40 minute trip at 45-50 MPH or a long hard steady climb, it leaves a 3.5" spot.† This is not horrible, but it drives me nuts.† If I ever have to pull the internals out again, I will have the race fixed and revert back to the neoprene style seal.†

Tom, Looking forward to seeing you again.† Hopefully, we'll stay dry this time around. Will I get to meet the M38?

Gun,† This engine is chain drive, so no oil squirter. Still, I think you all have convinced me to leave the oil pump alone.† I'll leave it be until it's time to pull the crank again.†

After many years of forum interaction, I'm excited to finally meet you at the FCT.† I can easily predict that you'll have a great time at this event.† Great Willys fun. Great people.† It's become quite popular, but even though it's grown to 40-50 Flat fenders, M38Mike has managed to keep it organized and enjoyable.† I'll be joining the fun early Tuesday morning.† I'll try to find you when I get there.† If you see me pull in, track me down.

Thanks again to all for your input. I appreciate it.

Tim
« Last Edit: 09/06/18 at 22:05:00 by athawk11 »  

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64CJ5
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Re: Oil Pressure and Rear Main Seal
Reply #9 - 09/07/18 at 11:17:06
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Tim my plan is to bring "Popeye".† We had some fuel delivery problems then some electric switch problems.† That is the way things go with some projects.
From what Mike posted the weather sounds good.†
Till we Jeep again.

Tom†
« Last Edit: 09/07/18 at 11:17:50 by 64CJ5 »  

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Gunslinger
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Re: Oil Pressure and Rear Main Seal
Reply #10 - 09/08/18 at 12:54:36
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Hey Tom,
I rebuilt Triple X about 4 years ago, The first rear main was a Felpro and apparently there were some tolerance issues, the seal disintegrated, went into the oil galley and went through the crank bearings, scored them badly and I had to have the crank turned, rest of the engine was ok as I got to it in time.  I don't recall what the replacement brand was.

So the saga continued, my builder also put in the oil pump seals that come with the rebuild gasket kit, so on that re-build apparently the new gaskets were thinner than the OEM gasket that was in the pump and when the pump got hot it locked up and broke a couple of teeth off of the pump gear, so happy I didn't lose the cam gear.  Any way we pulled it down and could not turn it by hand, loosened the cap screws 1/4 turn and the pump moved freely.  I got an NOS gasket from Midwest Military and miked the Felpro against the NOS and it was noticeably thinner. 

Hence the name Triple X, I had to pull that motor and rebuild it three times that summer, a real learning experience... if you like that sort of thing.
  

Climbs trees, hides in the long grass, hangs out with wet dogs...
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Re: Oil Pressure and Rear Main Seal
Reply #11 - 09/08/18 at 20:01:32
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While we are on the subject, I am getting ready to put my oil pan on.  How much of those two rubber plugs on the rear main do you leave sticking up.  I think I read 1/4 inch.  That correct?
  

Terry
1949 CJ3A† 11159† †body 11225 engine 11140
On preservation vs. restoration:† Roscoe Lee Brown "the Cowboys" when he met the whores on the trail:† "Well, I have the inclination, maturity, and the wherewithall... but unfortunately I don't have the time."
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