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Rear Main Seal Leak
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samstrader
Posted 2020-05-04 2:02 AM (#597738)
Subject: Rear Main Seal Leak


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When my engine (1955 259 V8 Poly) was first rebuilt in 2011, a rubber rear main seal was installed. This car originally came with a packing seal. It ran OK for a couple of hundred miles and then started leaking. Like 5 or 6 drops every time I park it. I drove it about 500 miles and the rear main bearing wiped out.

When I rebuilt it again this year (just main bearings and a new seal), I used a rubber seal again. It's the Fel Pro seal that Hot Heads said everyone uses. It's leaking again.

I'm trying to figure out what I did wrong. The crank has those shallow diagonal cuts in the steal area that I think were to help push oil away from the packing. I still have those cuts on the crank even though I'm using a rubber seal. I asked my machinist if a rubber seal would work with those cuts still in the crank and he said they would not be a problem

But something is wrong because the seal is leaking. I was very careful to put it in correctly (at least I think so). I'm sure the big lip is right. It is pointed to the interior of the engine. And the main bearing cap crushed down evenly and completely. I checked this.

Should I use a rubber seal or should I go back to the packing. My mechanic and Hot Heads said the rubber seal is way better but it seems to me like the packing would be a lot more forgiving.

Anyway. Sorry for all of the questions. Just looking for some guidance on how to do this right because I may fix this when I fix the cam bearing problem.

Thanks,

Sam
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Powerflite
Posted 2020-05-04 12:45 PM (#597756 - in reply to #597738)
Subject: Re: Rear Main Seal Leak



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Carefully inspect the seal when you take it apart to discover where the problem was. The packing works well at the beginning, but doesn't last as long as the rubber, in general.
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samstrader
Posted 2020-05-05 4:26 AM (#597808 - in reply to #597738)
Subject: Re: Rear Main Seal Leak


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Thanks Powerflite. Do you think the groves on the crank in the seal area would make the seal leak. It seems to me like those groves (which I think would be there for the packing) would make a rubber seal leak. If a rubber seal works, I think I can change that out without pulling the crank shaft. That's a big positive for the rubber seals.

thanks,

Sam
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GaryS
Posted 2020-05-05 7:01 AM (#597811 - in reply to #597738)
Subject: Re: Rear Main Seal Leak



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In 1964 I worked at a Chrysler-Plymouth dealer. We received a notice from the factory that several marine 318 crankshafts had been inadvertently installed in passenger car engines. Apparently, the knurling is ground differently on counter rotating engines, and the result was oil leaks that couldn't be fixed with new seals.

Not even suggesting that it's possible on yours, just saying that strange things happen and sometimes those little things mean a lot.
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samstrader
Posted 2020-05-05 12:13 PM (#597818 - in reply to #597738)
Subject: Re: Rear Main Seal Leak


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Thanks GaryS. If I remove the main, I know how to check what you are mentioning and I did not check this before. So it is a good thought. It just seems to me that you would not want any knurling if you have a rubber seal. Do you think this is right or am I just thinking wrong?
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samstrader
Posted 2020-05-05 12:14 PM (#597819 - in reply to #597738)
Subject: Re: Rear Main Seal Leak


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I forgot to say that it is definitely the little things that mean a lot. I've looked over so many little things working on my car. That's what experience is so valuable for. The experienced experts know the little things to watch out for.
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samstrader
Posted 2020-10-30 5:07 AM (#605056 - in reply to #597738)
Subject: RE: Rear Main Seal Leak


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I'm going to replace my rear main seal again. This is a picture of what is currently in the car. Is this seal installed correctly, in the right direction. Can you give me any pointers on how to make this seal work good. I've not been doing something right and my seal leaks pretty bad. This will be the third attempt to get a seal to hold.

I did check those groves for being a marine engine and my groves are angled correctly. The would push the oil back toward the inside of the engine when the engine is rotating. I think I'll use some 1500 grit paper and polish these groves a little just to make sure there is not any sharp edges that could hurt the seal.

Thanks....



(Rear Main Seal.jpg)



Attachments
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Attachments Rear Main Seal.jpg (247KB - 234 downloads)
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Shep
Posted 2020-10-30 7:13 AM (#605057 - in reply to #605056)
Subject: Re: Rear Main Seal Leak



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I have found the rubber seal does not work well on a knurled journal. I think the seal is backwards, can't see the angle of the lip.

Edited by Shep 2020-10-30 7:14 AM
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57chizler
Posted 2020-10-30 1:00 PM (#605065 - in reply to #605057)
Subject: Re: Rear Main Seal Leak



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Kinda hard to tell but if the yellow arrow is pointing to the seal lip, it's in correctly.



(Lip.jpg)



Attachments
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Attachments Lip.jpg (248KB - 228 downloads)
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samstrader
Posted 2020-10-30 2:15 PM (#605069 - in reply to #597738)
Subject: Re: Rear Main Seal Leak


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Thanks Shep and 57 Chizler.
The big part of the seal lip is on the engine side and the small seal lip is on the outside of the engine. It seems to me like the Knurling would make the seal not work good like Shep mentioned but I have heard from others it does work.

Shep, do you just use the rope seals? I can't install a rope seal now with the crank in the engine but almost chose that option when I had the engine out of the car. I might just work on polishing a lot of that knurling out with some very fine paper.

Any ideas?
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samstrader
Posted 2020-10-30 2:28 PM (#605072 - in reply to #597738)
Subject: RE: Rear Main Seal Leak


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Here's a better picture of the seal.

There are two seal lips, a small one and a thicker one... The thicker seal lip is on the engine side as installed. I think this is correct but just want to make sure.

Edited by samstrader 2020-10-30 2:30 PM




(Rear Main 1.jpg)



Attachments
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Attachments Rear Main 1.jpg (238KB - 237 downloads)
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wizard
Posted 2020-10-30 3:46 PM (#605077 - in reply to #597738)
Subject: Re: Rear Main Seal Leak



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Rope seals can be installed with a wire tool.
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samstrader
Posted 2020-10-30 3:59 PM (#605079 - in reply to #597738)
Subject: Re: Rear Main Seal Leak


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Thanks Wizard. Does anyone know where to get one of these wire tools. I remember them from a very long time ago. But have not seen one in many years. It is just a coated wire with a cork screw attached if I remember right.
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56D500boy
Posted 2020-10-30 4:21 PM (#605082 - in reply to #605069)
Subject: Re: Rear Main Seal Leak



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MoparMall/i.monit/TemeculaValley Mopar says that they have both the rope and the rubber seals in stock. PN 1326 093 (or 1326093 when doing a Google search).

I wish the instructions for the Rope Style were bigger/clearer.

https://www.ebay.com/itm/Crankshaft-Rear-Seal-for-1955-1959-Plymouth...



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wizard
Posted 2020-10-30 4:35 PM (#605083 - in reply to #605079)
Subject: Re: Rear Main Seal Leak



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samstrader - 2020-10-30 9:59 PM

Thanks Wizard. Does anyone know where to get one of these wire tools. I remember them from a very long time ago. But have not seen one in many years. It is just a coated wire with a cork screw attached if I remember right.


Yes, just a wooden screw soldered on a wire with a T-handle. coat with shrink tube...
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wizard
Posted 2020-10-30 4:36 PM (#605084 - in reply to #605079)
Subject: Re: Rear Main Seal Leak



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samstrader - 2020-10-30 9:59 PM

Thanks Wizard. Does anyone know where to get one of these wire tools. I remember them from a very long time ago. But have not seen one in many years. It is just a coated wire with a cork screw attached if I remember right.


Yes, just a wooden screw soldered on a wire with a T-handle. coat with shrink tube...
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56D500boy
Posted 2020-10-30 5:59 PM (#605087 - in reply to #597818)
Subject: Re: Rear Main Seal Leak



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samstrader - 2020-05-05 9:13 AM
Thanks GaryS. If I remove the main, I know how to check what you are mentioning and I did not check this before. So it is a good thought. It just seems to me that you would not want any knurling if you have a rubber seal. Do you think this is right or am I just thinking wrong?


Wrong. The knurling is there for a reason. It helps to push the oil back into the engine, away from the seal. The seal is there to deal with the oil that the knurl does not grab and push back.

Marine engines: There are two kinds. Clockwise rotation and anti-clockwise rotation. These are for when they are used in pairs, so one screw is turning one direction and the other is in the other rotation.

My NOS parts guy who has a NOS rear seal for me (he says rubber is just fine, not worse than rope) told me a story about somebody with a gravel truck with a 413 that was being rebuilt and reinstalled when he was working at a Chrysler dealership. After the engine was back in the truck, they could NOT get the real seal to stop phishing oil. Even after two tries with rear seals. Hmmm....so they phone the engine rebuilder and ask "By chance, did you have any Marine 413 in your shop at the same time as the gravel truck 413?" The answer was "Why yes we did, we had a matched pair of Marine 413s at that time". Oops.

Turns out that the truck 413 crank got swapped with the wrong rotation Marine 413 crank and the knurling on the crank in the rebuilt truck 413 was *PUSHING* oil to the rear seal and the rear seal couldn't cope. Many $$$ later the rebuilding shop fixed the problem by swapping the cranks back.

That's just one story.

The other story he had I had heard before: The early V8s (1955) had an issue that as the block aged it shrank at the rear of the block, lifting the rear crank journal up into the block. Not by much (0.004" in his case).
This was enough to break his crank while drag racing (back in the day). He thought that he had a rod knock. The break was eventually discovered by removing the pan and rotating the crank using the front pulley nut while the rear of the crank was observed. Any discrepancy in rotation = a fracture in the crank. His was around the No. 7 rod journal. Not pretty. New crank and line boring the crank journals and caps.

Just some things to consider/eliminate as a you investigate further.



Edited by 56D500boy 2020-10-30 9:04 PM
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Shep
Posted 2020-10-30 7:09 PM (#605088 - in reply to #605072)
Subject: RE: Rear Main Seal Leak



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Seal looks correct. I would not advise polishing the knurling.

Edited by Shep 2020-10-30 7:13 PM
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56D500boy
Posted 2020-10-30 11:30 PM (#605097 - in reply to #605087)
Subject: Re: Rear Main Seal Leak



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I forgot to add that my NOS parts guy who was a Chrysler Dealership mechanic for 35 years said that the almost always replaced the top half of the rubber rear main seal without having to drop the crank. As I understand what he said, you retreve/remove the upper half using the tool that Sven (wizard) described.

After cleaning up the old seal galley, you grease up the new upper seal half and push it in from one end. He said the trick was lots and lots of grease.

He has a NOS rubber rear seal that I am going to get tomorrow so I have it on hand when I tackle this once the snow flies.

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56D500boy
Posted 2020-10-31 2:43 AM (#605102 - in reply to #605097)
Subject: Rear Main Seal Removal and Installation Tools



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These (Lisle 27000):

"Lisle upper rear main seal remover and installer tools, a.k.a. Sneaky Pete, allow you to service rear main seals without dropping the crankshaft. The kits include everything needed to speed up a long, slow job. The corkscrew puller makes it easy to remove the old seal, and to install a new seal, you use the included pulling wire with removable T-handle and spring steel clip that grips the seal firmly as it is pulled into position. Lisle furnishes two extra clips, and these tools will save you time, frustration, and money. "

https://www.summitracing.com/parts/lil-27000

Using the Sneaky Peak on a "Rope" (Asbestos (OH NO!!!) upper rear main seal:

https://www.youtube.com/watch?v=pXQw2luGYPQ

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samstrader
Posted 2020-10-31 4:13 AM (#605103 - in reply to #597738)
Subject: Re: Rear Main Seal Leak


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Thanks Dave and Dave. I have heard rubber seals last longer than rope seals, and they are easier to install with the engine in the car, so I'm going to try one more time to use a rubber seal.

The youtube video on Sneaky Pete was very interesting and really good information if I decide to go with a rope seal. I can get the rubber seal that is in mine now out pretty easy and without the Sneaky Pete but I would need the Sneaky Pete to put a new rope seal back in.

I looked at some you tube videos on how to install split rubber seals and saw a couple of things I didn't do the last time and this is probably why my seal is leaking. I did not stagger the split of the two pieces away from the bearing cap seam where the bearing cap seats to the block and I didn't use any RTV on the ends of the seal halves or on the bearing cap to block joint. You can't use very much RTV but videos say you can use a little. These videos are very helpful actually!!! Here is one of the videos I thought was very good:

https://www.youtube.com/watch?v=WSy5hywk_ls

Here is another one:

https://www.youtube.com/watch?v=24bh_F6trQU

And here is one for installing rope seals. They are a lot harder to install:

https://www.youtube.com/watch?v=vVLXAGKjnGI

And this is the best one for replacing Rope Seals (with engine out of car) but has quite a few things to watch for...

https://www.bing.com/videos/search?q=rear+main+rope+seal...






Edited by samstrader 2020-10-31 4:13 AM
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samstrader
Posted 2020-10-31 4:17 AM (#605104 - in reply to #597738)
Subject: Re: Rear Main Seal Leak


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Forgot to mention that I checked my knurling and it is in the right direction and I don't think my crank is cracked or broken because I just had the mains reground and any break would have shown up then. I have been only breaking in the engine since the rebuild and have not put enough pressure on any thing to break the crank. At least I don't think so. But I'll double check the crank when I work on the seal.
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samstrader
Posted 2020-11-11 1:16 AM (#605526 - in reply to #597738)
Subject: Re: Rear Main Seal Leak


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I installed a new rubber rear main seal with the engine in the car. It was actually very easy once you get to the inside of the engine. So far it is not leaking but I"ve only driven 30 miles so it may start leaking soon.

I already had a rubber seal so my upper seal came out real easy, just like the videos above show. Tapped it with a punch a couple of times and then pulled it out (actually rolled it out) with a pair of needle nose pliers.

I lightly rubbed the seal surface where the knurls are with 1500 grit sand paper. I didn't try to remove any of the diameter or the knurls; just trying to make sure there weren't any burrs that might scratch or damage the seal. I didn't feel any thing on the shaft while doing this.

I put RTV on the seal ends, just a very small amount and I clocked the seal halves .415 inches. I also put RTV on the rubber pieces that fit into the bearing cap and a very small amount of RTV on the back edge of the bearing cap just like the guy in the video said.

Hopefully it won't leak this time. But the purpose of this note is to say the change out is very easy to do.
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GaryS
Posted 2020-11-11 3:37 PM (#605541 - in reply to #597738)
Subject: Re: Rear Main Seal Leak



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I had a problem with a B, 400 engine that wouldn't seal, so the last time I tried to fix it I too put a ribbon of sealant on the engine and cap sides of the rubber seals before I installed them. No more leak, so I now do the same during assembly of all my engines and have not experienced any more rear main leaks on start-up. Coincidence?...maybe, but in my case it seems to do the job.

Edited by GaryS 2020-11-11 3:40 PM
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