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Old 09-01-2013, 04:16 PM   #1
cw
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Default Rear Main Seal - Help please

We blew the babbit out of No. 4 and I think failed the rear seal.
The rear main seal appears to be broken. Can you confirm?
Is this difficult to repair?




High resolution picture is here
https://skydrive.live.com/redir?resi...4Vw_I-3eJM&v=3
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Old 09-01-2013, 04:42 PM   #2
Kurt in NJ
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Default Re: Rear Main Seal - Help please

In the picture posted the rear seal is not visible, but it does look like some of the front thrust flange is missing on the rear main cap.
A stock A engine doesn't have a "rear seal" as we think of one today, it just had a slinger and grooves with a drain on the bottom, but there are many different methods that have some kind of aftermarket "seal" that has been tried as an "improvement" or repair instead of fixing the root cause of leaks.

Without having more than a picture to go on the #4 rod looks to of had a bonding failure of the tinning to the babbitt.

The next step is to take the rear main cap off to look there at the "seal" area, and the babbitt
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Old 09-01-2013, 06:02 PM   #3
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Default Re: Rear Main Seal - Help please

Thanks
Is this the area of the thrust flange?
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Old 09-01-2013, 06:22 PM   #4
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Default Re: Rear Main Seal - Help please

Yes that is the area where there would normally be babbit.
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Old 09-01-2013, 06:55 PM   #5
Mike V. Florida
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Default Re: Rear Main Seal - Help please

The vendors have a bronze thrust bearing that can be used.
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Old 09-01-2013, 07:53 PM   #6
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Default Re: Rear Main Seal - Help please

Mike, it won't work on the front.
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Old 09-01-2013, 07:54 PM   #7
James Rogers
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Default Re: Rear Main Seal - Help please

Quote:
Originally Posted by cw View Post
Thanks
Is this the area of the thrust flange?
Yes, and all is lost. Time for some new mains and the rods don't look too good either.
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Old 09-01-2013, 08:00 PM   #8
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Default Re: Rear Main Seal - Help please

I second that!
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Old 09-01-2013, 09:08 PM   #9
glenn in camino
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Default Re: Rear Main Seal - Help please

Don't give up. Too many engines are rebuilt when a simple fix is possible.
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Old 09-02-2013, 03:13 AM   #10
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Default Re: Rear Main Seal - Help please

If everything else is sound with the engine, a new babbit job is not that terribly expensive. I fear if one part of your babbit system is failing, it is time to redo the whole thing. Most likely, anyway. Send it to James Rogers.....
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Old 09-02-2013, 11:16 AM   #11
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Default Re: Rear Main Seal - Help please

Could we repair the rear main and replace the rods with parts from a catalog?
Or do we need the block mains rebabbitted or inserted?

We have a Winfield head of unknown compression. Could this problem have been caused by too much compression in the head?

For a go job would we be better off with a B/C head and inserted mains and rods?

thanks
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Old 09-02-2013, 05:30 PM   #12
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Default Re: Rear Main Seal - Help please

So did you have any trouble with pre-ignition, or detonation (pinging), did your troubles start soon after installing the sparkplugs ---they appear to have quite a few threads exposed in the combustion chamber, this will change the sparkplugs "heat range"

Abnormal combustion can damage any bearing, babbitt or insert
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Old 09-02-2013, 06:33 PM   #13
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Default Re: Rear Main Seal - Help please

No problem with pinging or pre ignition. She fired and ran well. We did have a noise under load. Could have been the rear main?
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Old 09-02-2013, 07:17 PM   #14
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Default Re: Rear Main Seal - Help please

I agree with Kurt. There should be no exposed threads, as they can load up with cabon and wreck the threads in the head when you remove the plugs. The plug will also run hotter than it should.
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Old 09-03-2013, 12:10 AM   #15
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Default Re: Rear Main Seal - Help please

The plugs are wrong, take the head to NAPA and fit plugs of the proper length that only expose the grounding strap.
The head with the flycut is probably a 6:1 CR. Aluminum or cast iron? Should be cast iron. Does it say Super Winfield on the water passage on top? Is the red paint original? Jim Brierely is the guy to ask about Winfield heads and the repos. But the head and plugs are not the problem. That head is fine on an A and did not cause the babbitt probs.
First, the rod oil grooves are wrong, but workable, but the reliefs at the parting line are all wrong from what I can tell. It also looks like in the photos that there is "gouging" of the babbitt from "foreign material", ie, hard sediment. Get an oil filter. Is the crankshaft scored too? And the babbitt looks thin. Herm Kohnke can analyze this best if he is still reading this forum. Have not heard from him in awhile and I miss his contributions.
A "mere" chip in the thrust face babbitt can be tolerated without repair, so long as there is no separation from the underlying cast iron, but since the rods were done wrong I expect the mains were done wrong too. I suggest you get a new babbitt job from someone who knows what they are doing. Ask questions. Search forums on this issue on this forum to learn about babbitt jobs.
FWIW, it is not so simple as just ordering rods from a catalog. They have to be fitted to the crankshaft. Your crank may be, and probably is, undersized. There are threads here on that topic.
IMHO, you do not need inserted rods and mains unless you go to a full pressure oil system, and that is a major modification, unnecessary except for extreme conditions. I run a fairly hot engine, "speed job," as you put it, with correct babbitt and splash oil and a pressure center main from Dennis Pirano's kit. Just don't go over 4000 rpms, which is my personal redline. However, some folks do inserts anyway, up to you if you are willing to spend the money.

Last edited by PC/SR; 09-03-2013 at 03:07 AM.
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Old 09-03-2013, 11:23 AM   #16
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Default Re: Rear Main Seal - Help please

The crankshaft is not scored and measures about 1 31/64 to 1 1/2.
If the rods are replaced and shimmed to fit the crank. Would the rear cap be ok as is?

The Winfield is aluminum. I believe from Ford Specialty Parts.
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Old 09-03-2013, 07:09 PM   #17
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Default Re: Rear Main Seal - Help please

You need an exact measurement of the crankshaft journals. Shims can adjust for a few thousandths, but beyond that things get way off. Some babbitt guys will cut rods to fit on an exchange basis, but you have to know the exact dimensions.
No way to tell about the mains without inspecting them, but with the chip off now, and the apparent chip on the rod looking like a bonding failure as noted by Kurt in NJ, I would not trust it.
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Old 09-03-2013, 09:08 PM   #18
Kurt in NJ
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Default Re: Rear Main Seal - Help please

You will have to go through all the bearings to check for damage, and to adjust clearances ---
I know that you may not like what you see, I didn't when I first took off my rear cap 3000 miles after a rebuild --it was just crumbs, it only had a little chunk off the thrust too when i first took off the pan.

The crank really needs to be measured accuratly with a micrometer ---a harbor freight digital caliper for 9.95 with coupon can get you close, tell if std, .010, .020 or so with a +- .003 tolerance or so, but an accurate micrometer is best.

Babbitt is made to fit crankshafts, crankshafts are made to fit inserts ---for babbitt a crankshaft can be any size as long as it is straight and round ----but with inserts the crankshaft has to be the exact size for that insert.
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Old 09-03-2013, 11:14 PM   #19
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Default Re: Rear Main Seal - Help please

Mr. PC, and Kurt seem to have every thing under control.

The rod was tinned, and the babbitt didn't stick to the tinning.

If the rod was not tinned, the metal would be dark.

So the tinning stayed, and the babbitt fell out as the two surfaces didn't melt together, as in cold solder joint.

The rod next to the burnt out one has some babbitt splatters on it, and was not cleaned. If you are sloppy and don't clean all the rod metal, the splatters can come off and also cause bearing problems.

Like the boys said, be safe check all the bearings.
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Old 09-04-2013, 09:45 AM   #20
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Default Re: Rear Main Seal - Help please

Thank you all for the help.
I will look into an engine rebuilder.
Can anyone recommend one in Michigan?
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