I’ve been dealing with a nasty oil leak on my 460. Originally thinking I️t was the rear main seal, after tons of reading. So I️ pulled the oil pan and behold! An 1/8” chip on the rear main bearing cap. With a glob of silicone right on the outer edge. (Previous owner) Now the chip sits on the outside edge of where the pan and gasket set. And I️ cannot find a replacement on the internet anywhere! So my question is, 1. Where can I️ find a suitable replacement? 2. Machine shop around Orange County N.Y.? 3. Spot weld myself? Seeing as that it’s on the outside edge of the gasket lip. Sent from my iPhone using The H.A.M.B. mobile app
My thoughts: 1) the rear main cap probably has to be matched / machined to the block to Properly hold the bearing shell round and precise. So I don't think you can just replace the bearing cap. 2) I would probably try Tig welding a little silicon bronze to fill the missing piece. It is basically brazing so temp is low so should not cause distortion. Also the cap is a cast of some kind. The bronze won't be effected by the high carbon content. The bronze is soft enough that you should be able to work the shape back with hand tools and files. Welding is an option, but the likely high carbon content will create a hard weld that will be difficult to work with. You would need to use nickel. I have repaired many items with Tig bronze and it works superbly. Sent from my iPhone using H.A.M.B.
Usually if there's a problem with a main cap, you find a replacement cap from a junk block. Then get the block align honed with it's new cap in place.
Squirrel is correct. The caps are mated to each block, but get the cap from a block and align it. You will be back on the road in no time! Sent from my Pixel 2 XL using The H.A.M.B. mobile app
Since it's on the edge of the cap with no stress, I would try cleaning it well with brake clean and use JB weld. Then file it to shape. After all, all it has to do is seal to the oil pan.
That chip is from a part of the cap that shouldn't see any oil. The pan gasket should seal it from getting to that point. Unless there's some other damage/deformation associated with that chip, that's not the source of your leak.
The more I️ think about I️t. You guys should be correct. really shouldn’t affect I️t. And looking at the old pan gasket. I️t is deformed where that chip is. So possible too much silicone mishaped the gasket? Or over tightening has done it Sent from my iPhone using H.A.M.B.
That looks like the sealer was put on there after it was assembled. I would have to take a look at the rear seal.
From the appearance of the crankshaft throw it appears that the crank has been seriously reworked then re-balanced. Do you know any of the specifics of this engine, stroker, etc.? Was the engine stroked then rebalanced or just some serious machine work done on the crankshaft to lighten it? There could be more issues than this one cap which as Squirrel stated will require line boring if replaced.
Is the oil leak isolated to just the rear of the engine in that specific area? If so the cap could be cracked, highly unlikely but it could be and should be investigated before slapping a Band-Aid on it with just a new gasket. Is this a stroker? Does the engine vibrate when tached up high in the RPM range?
Not trying to point fingers at the engine builder, but while you have the pan off, pull the cap to confirm the rear main seal isn't installed backwards. I've seen this hiccup many times, especially to non-Ford specific engine builders.
Maybe the seal was put in backwards. Or if the maincaps have been machined and the new seal may lost its crush and is distorting the seal. The seals are also offset when there placed in the block and maincap.
There was a small amazing of sea page from the front of the pan. And Engine runs smooth at high RPM. Sent from my iPhone using H.A.M.B.
Have you pulled the cap and looked at the crankshaft seal? As others have said, that really shouldn't allow a leak. I liked to clean the surface of the cap and seal with thinner and use 3M weatherstrip adhesive to glue it in place.
attempted to pull the rear main cap, but with the motor still in. Might be impossible. Caps in there pretty good. I️ don’t want to damage trying to remove Sent from my iPhone using H.A.M.B.
As stated above in saltflats post, loosen the bolts and tap it with a hard rubber faced hammer is what I use and examine the bearing cap. Check the seal as engineman suggests and possibly get the cap magnafluxed while you have it off just to eliminate any cracks. If you even have to just replace the one rear cap you will have to get the entire block and all other mains align bored. So rule out a cracked cap before proceeding any further, have the cap magnafluxed..
Ok, going to go at this again. Thursday. It’s down to 6 degrees To be continued... Sent from my iPhone using H.A.M.B.
If you pull the cap, brake clean it and let it set, if it's cracked, oil will migrate back out of the crack and should show up pretty easy. The main cap and rear pan gasket, should be completely free of oils and grease, a little dab of sealer in the corners is all thats needed for leak free installs. Also, be sure the pan sets flat all the way around.
I highly recommend changing the rear main seal while your so close. While doing so, offset the seal approx 1/4" so that the parting line of seal is not at the same parting line as the main cap. Also a very little dab of silicone on the ends of the seal before you bolt the cap back in place. Don' forget to oil the seal and bearing. Also another thong I've found....we used to use a one piece pan gasket (I believe it was actually for a 330 or 390?). I would use 3m spray adhesive to spray the block surface then I could stick the gasket up to it perfectly and easily bolt oil pan in place. The gasket we used had to have very end holes cut out for larger bolts....youll understand if you see it.
Update to where this stands. As recommended, pulled the cap. Looked to be in good shape. (Other than the chip)Pulled the seal, also looked to be in good shape. I️t was in the correct way. Replaced rear main seal. Offsetting the install in block to cap. Dab of silicone, new pan gasket. But as soon as I️ reach operating temp. Steady drip occurs. going to attempt a different rear seal, and pan gasket. I️ also checked crush depth, and was at .05 on both sides of gasket. Possibly not enough from manufacturers? Sent from my iPhone using H.A.M.B.
Crush depth should be set @ 0.015-0.020. If the engine has been line honed it can throw things off. Had to give my rear seal a touch up to bring it to spec.
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