need rear main seal information

Alaska Jim

Alaska Jim

Well-known member
I will try to keep this long story as short as I can, and hopefully I will get some answers, and/or suggestions.. I recently bought a vehicle that supposedly ( and all indications seem to verify this ) the eng. is fresh with only 4 miles on the complete drivetrain. I get the vehicle home ( shipped to Alaska then trailered to my home ) I checked the vehicle over, all seemed ok. had it running several times although just at Idle and a little above. took it for a 18 mile drive and discovered a large trail of oil following me up my driveway looked to be the rear main seal. I removed the Pan and the seal retainer. It does not have a rope seal. it has the new replacement plastic/neoprene style seal. I got to looking at the retainer and it is marked ECZ-6335-A. I believe this to be a 312 seal retainer. the eng is supposed to be a 272 . the main caps are marked EBU-6329-B the rods are marked EBU-9502-A and the block is marked ECG. The seal in the retainer has a FelPro # that matches for a 272/292. my question is this. Is the seal retainer for a 312, and is this a mismatch that will cause a leak at the rear main seal? I know that the 312 has a different diam . journal for the seal, and requires a different rear main seal than the 272/292. do I need a 272/292 seal retainer or will the 312 one work with having a leak? what to do, what to do? any suggestions?
 
The 312 rear seal surface on the crankshaft is 1/8" larger in diameter than that of the 272/292 engines. As such, the seal retainer for a 312 is different from those for the 272/292 engines. In your case, it sounds like a rear seal retainer for the 272/292 engines is required. If you have the ECZ rear seal retainer, then you likely have a healthy slot or opening at the seal to crankshaft surface for the oil to pass through.

I have the correct seal retainers here and will be happy to simply swap you a 272/292 seal retainer for the ECZ 312 seal retainer that you have. My contact information is at www.eatonbalancing.com . Ted Eaton.
 
I'm wondering if they did use the 312 retainer and seals, how did they get the top half in the block. You might check to see if the top half is the right one, just in backwards.
 
Ted, thank you for the information. it is what I suspected. Thanks for the offer on the swap, but I do have a spare for the 272/292. now I have a retainer that I needed for a 312 I am building from parts. who ever installed the seal put the correct seal in the wrong retainer. you can still read the # on the seal and it is correct for a 272-292. they did "glue" it in with what looks like aviation sealer. it was a big mess. ponymare---they used the correct seal, just the wrong retainer. there is no way the larger 312 seal would fit in the block and still be able to put the retainer on. As far as I know Best Gaskets are the only one who make a modern seal for the 312, and it is an orange color. the ones I have for a 272/292 are FelPro, and they are black with the part # embossed into the seal, that is how I identified the seals as being correct, and only the retainer being possibly wrong. I appreciate all the help and suggestions. now I need to get out there and put it back together. Thanks again, -----Jim
 
Best Gasket has discontinued making the orange seal for the 312 engine. The latest 312 neoprene seal from Best Gasket is now black. That change came about due to the quick wear factor on the orange seal. Ted.
 
I just rebuilt my 56 312 and used the best gasket seal(black). I do have the right retainer but the seal leaked anyway. After pulling the gasket I found that the inside diameter was a little large for the crank. Before some one suggest it, I DO have a 312 crank! I ordered a new gasket from NPD and found it to be a felpro gasket that has been "reworked" to fit the 312. I checked the inside diameter and it was perfect. Installed it and have not had any leaks.
 
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