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By oldcarmark - 8 Years Ago
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I am working on mine Today to fix a Leak at rear of Engine. Been leaking since I rebuilt it about 10.000 Miles ago.I used the Best Neoprene seal when I assembled it. Followed Ted's Instruction Sheet. When I pulled it apart Today I verified that the Seal was in facing the correct Direction with the Lip facing towards Engine. The Nails in side Seals were in correctly. There's traces of the Black Sealer at the Bottom of the Seal Retainer and on the Parting Surfaces. I can see on the Crank a nice outline of where the Seal has been riding. I can't see where I did anything incorrectly. I do have a new Best Set to go back in. I am hesitant to try and replace the upper Half because I don't see how anything could be wrong with it. Bottom half is good.I am working on my back under the Car which is not real conducive to working comfortably. Trying to get the Upper Seal replaced may be more trouble than its worth as its only been in for less than 10,.000 Miles. Any Suggestions? The Leak seems to be from rear main. The Valley Cover was modified using tapped machine Screws so its not leaking. The Flex Plate for Convertor is clean and dry so I don't think its the Cam Plug. By the way the Pan will come off with #5 at TDC but the Sway Bar needs to be unbolted and moved out of the way. I don't remember that ever being mentioned before. Cutting the Bracket off where the Steady Rest used to bolt on would be helpful too..Looking for any input before I put this back together. Thanks
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By miker - 8 Years Ago
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If that seal is "orange" in color, it's one of soft seals. When I used one 10 years ago it failed in 500 miles. Then new ones are black, and neoprene. I think the orange was silicone. The new one seems to be holding fine. I replace the top half also, no choice with those.
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By oldcarmark - 8 Years Ago
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The Ones in there now and the Replacement Set I have is Black for 292. Both are"Best". I think the Orange Ones were for 312.
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By miker - 8 Years Ago
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Yes, mine was a 312, I don't know if they made them for the 292 . It just put me off a lot to have a new "improved" seal from a major manufacturer fail that quick. And I know I wasn't the only one.
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By Ted - 8 Years Ago
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Mark. I take it that you are using the Bst Gskt black seal and your engine is a 292? I’ll suggest also replacing the top half of the seal while you have the pan off. For rear seals that are tight within the block groove, have someone else turn the crankshaft via the damper bolt while you put pressure on the rear seal edge with a small punch or screwdriver. This typically helps in removing the upper half of the rear seal.
Be sure to check the seal surface of the crankshaft to insure it’s smooth and not pitted or rough. I have had to re-machine the rear seal surface as much as 0.010” to get a fresh ride for the seal.
The current run of neoprene rear main seals from Best Gasket for the 312 engines are now black. The rear seal offered for the 292 engines was already black. There are two different part numbers involved simply due to the crankshafts having different crankshaft and block seal diameters between the 292 and 312 engines. When Best Gasket started producing a rubber seal for the 312, it was orange and this I assume was so that the 312 seal could be easily differentiated from the black seal that was being used for the 239, 256, 272, and 292 engines. The orange seals were made from a softer material and wore quite quickly. Once this issue was noted, the Best Gasket 312 seals were revised where they were being made from the same ‘black’ material as the 292 seals. Be forewarned that Best Gasket has tried to get all those orange 312 seals off of the vendors shelves but those seals still manage to show up on occasion through Ebay sales and vendors that are not aware of the problem.
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By oldcarmark - 8 Years Ago
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Ted (7/13/2017)
Mark. I take it that you are using the Bst Gskt black seal and your engine is a 292? I’ll suggest also replacing the top half of the seal while you have the pan off. For rear seals that are tight within the block groove, have someone else turn the crankshaft via the damper bolt while you put pressure on the rear seal edge with a small punch or screwdriver. This typically helps in removing the upper half of the rear seal. Be sure to check the seal surface of the crankshaft to insure it’s smooth and not pitted or rough. I have had to re-machine the rear seal surface as much as 0.010” to get a fresh ride for the seal. The current run of neoprene rear main seals from Best Gasket for the 312 engines are now black. The rear seal offered for the 292 engines was already black. There are two different part numbers involved simply due to the crankshafts having different crankshaft and block seal diameters between the 292 and 312 engines. When Best Gasket started producing a rubber seal for the 312, it was orange and this I assume was so that the 312 seal could be easily differentiated from the black seal that was being used for the 239, 256, 272, and 292 engines. The orange seals were made from a softer material and wore quite quickly. Once this issue was noted, the Best Gasket 312 seals were revised where they were being made from the same ‘black’ material as the 292 seals. Be forewarned that Best Gasket has tried to get all those orange 312 seals off of the vendors shelves but those seals still manage to show up on occasion through Ebay sales and vendors that are not aware of the problem.
Thanks Ted. It is a 292. Yes it is another "Best" Seal Kit I am using. The Crank was not turned when I rebuilt it as was apparently not needed. Polished only and still Standard Size. I will have a good look at it before I put it back together.
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By 57RancheroJim - 8 Years Ago
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Did you offset the seal so the parting lines aren't the same as the parting line between retainer and block?
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By oldcarmark - 8 Years Ago
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I did Jim. Followed Ted's Instruction Sheet.
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By 57RancheroJim - 8 Years Ago
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I did everything correctly I think, first time using the Best gasket black seal and have a minor leak about the size of a quarter over night. I just live with it, not bad enough to me to redo it.
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By Rudder2fly - 8 Years Ago
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I never did stop the leak on my seal. See my previous posts on this subject. I have heard that the Y's mark there spot! I guess that is so, I'll just live with the leak as long as it doesn't become major. I have yet to get the car on the road. All the leakage has been on a test stand. Soon I will see how bad this may be.
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By oldcarmark - 8 Years Ago
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I did get the Upper Half replaced Today. Dropping the Crank by backing off the main Caps makes it easy. Just used some White Grease and compressed the Lip as I pushed it in a little at a Time. Still nothing wrong with One I took out so we will see if this makes any difference. Going to put it back together Friday. Repainted the Oil Pan while I had it off. Mine is more than One Spot the size of a Quarter.
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By 57RancheroJim - 8 Years Ago
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Good luck this time around. Seeing your other post do you know if the seal material is compatible with Synthetic oil?
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By oldcarmark - 8 Years Ago
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I am not planning on using the T-5 Synthetic. T-4 is what the Rotella-T was before they added the 4. Been using it for Years. never had a problem with it. **Question for Ted**- On Teds Instruction Sheet there is a Tube of Ultra Black RTV Gasket Maker pictured. Is that what Ted uses in the side of the Seal Retainer just before the Seals are inserted? It appears to be clear in the next 2 Pictures. Will the Black do the Job?
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By oldcarmark - 8 Years Ago
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Question for Ted in previous Post.
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By Ted - 8 Years Ago
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oldcarmark (7/13/2017)
.....**Question for Ted**- On Teds Instruction Sheet there is a Tube of Ultra Black RTV Gasket Maker pictured. Is that what Ted uses in the side of the Seal Retainer just before the Seals are inserted? It appears to be clear in the next 2 Pictures. Will the Black do the Job?
I only use the Ultra Black RTV here in the shop. I have no experience with the plain RTV for the side seals. I'll add that when I do the dollop of RTV and the side seal insertion, the rear seal retainer is not bolted down yet. It's sitting about 1/16" off the block mating surface as this allows the RTV to creep under the seal retainer when the side seals are pushed into place. When the seal retainer is brought on down and tightened, this insures that the mating surface between the seal retainer and the block is also sealed.
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By oldcarmark - 8 Years Ago
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Thank You. That's what I have on Hand. Just wanted to verify that's what You use. If this thing still leaks after this I don't want to second guess myself that I used the wrong Sealer. Going back together Today. Let You know if its a successful repair.
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