Engine Oil Drain Back Tube

JC60B

JC60B

Member
On a previous thread there was a link to a site for engine oil leaks. Good info but doesn't mention rear leak just after shut down as my '29 60B does. I'm thinking maybe the oil drain back tube is plugged. The engine doesn't leak much running but sure does once shut down. I bought an oil pan gasket and going to pull the pan to investigate. Is the anything else to check that could cause a simular leak. Oh this is a truck engine if that matters. Thanks.
 
some truck engines on grain trucks had a drain pipe with a ball check valve in them, to prevent back flow when they were tipped up to unload grain. The ball occludes the oil flow. When the engine is running, suction from the pump assists drainage from the tube. When the engine is off, only gravity is in effect, and a ball type drain can overflow out the back. If I recall, the ball type tubes as well as the early engines' tubes were smaller diameter too. Replacing the tube with the later larger diameter can help. Another common cause is a small leak kept inside the flywheel housing by the turbulence of the spinning flywheel. When the engine is shut off, the oil drains out. The link to the rear main page is here:
http://www.antiqueenginerebuilding.com/REARMAINLEAK.html

do not assume anything about rear main leaks. Check each possibility carefully. It could be a combination of more than one cause.
 
Verify that the oil level is proper. To much oil will cause a leak at the rear main. When the oil is drained about a quart will stay in the valve chamber and rod dip troughs.
 
Well I pulled the oil pan today and Pat, you are right. It has the check ball in the drain tube and it is smaller diameter. But that is the least of my worries.
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The corner edge of the cap that meets the aluminum block seal is broken off and that is the cavity the drain is in. Also the thrust end of the bearing is broken (pieces still in place). I took some pictures. Could I replace this rear main cap or were these engines linebored? If so I may have to try and somehow repair this one for I am not up to doing a major overhaul right now. Also since this cap is the forged one with the thicker bolt bosses would a later one from a car work?
 

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The forged caps had the shorter bolts and bolt bosses. I would try to build up the missig part with weld and grind it to shape using a Dremel.

Actually you could also clean and dry it well and build it up with JB-Weld.
 
Suggest you contact Bill Barlow at (541) 389-2694. He can likely do up a new cap for you to match the old one.
 
Thanks Tom. I stand corrected. Thicker boss is cast. Lets say that I can repair the cap with JB Weld, could it be drilled and tapped to accept the larger diameter tube? Then there is that broken thrust bearing issue. Can a cap be re-bearinged by itself or is the block machined together with the caps which would make more sense to me. And now right after Christmas, it's sense I have not dollars.
 
30Tudor said:
Suggest you contact Bill Barlow at (541) 389-2694. He can likely do up a new cap for you to match the old one.
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Thanks. That would be great if he could do that. Where is he located? Does he have an Email? Would I send him mine for size?
 
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Bill can do individual caps-that is what he told me when he did my engine. He is located in Bend Or. and you will have to send yours to him, he even has spares that he may be able to swap out.

Mike
 
if you can get a replacement cap poured, find a good core. Yes, it can be drilled to accept the larger tube. It must be drilled so the tube slants slightly away from the pan but not too close to the crankshaft. I'm sure if Bill can make you a replacement cap, he can modernize the tube for you. You will probably have to fit the cap to your journal by bluing and scraping it, a methodology that seems to have been lost in time, but which was once very common. Back in the 70's, when I was a poor kid just out of college, I fit a .030 under cap to a .020 journal. It took a long time, but worked well with no leakage.
 
Just have another cast cap with the larger return pipe rebabbited to the size you need.You may have to file the end thrust to get correct clearance.Main caps were changed quite often back in the day.Make sure sure block face of cap is perfectly flat & shims are touching C-shaft.
 
I got in contact with Bill Barlow and he can fix me up with a cap. He told me just shim the original cap to .0015" and send it to him with the shims. From that he'll know the crank size for the new cap. Problem was, no shims was .002" and the crank would not make a full revolution, so out of round bad. That and pitting on the journal and .020" end play - time for different crank. This one already ground M .035 and T .030. Found a used one polished and at .025 so Bill is going to build a cap for this crank. I'll have to get my block and rods machined to fit new crank. Then I'll add that brass rear main thrust washer A6334 for my end play issue and re-ring etc while apart. Anyone know who in my area (Edmonton Alberta) does this old school babbit machine boring? I really opened a can of worms with this oil leak repair.
 
it does not make sense to me to have a cap poured in one place, and the rest of the engine somewhere else. Why not have the entire job poured and line bored in the same shop?? you can buy rods already made to the standard under sizes from most vendors.
 
Since the new crank is larger diameter, there already is enough babbit so why repour the whole thing. And Bill figured there shouldn't be an issue. Don't see any pitting in the babbit so far. I'm pulling the engine out this weekend. Once it's apart I'll have a better look.

PS why does this site keep logging me off when I try to post?
 
JC60B said:
Since the new crank is larger diameter, there already is enough babbit so why repour the whole thing. And Bill figured there shouldn't be an issue. Don't see any pitting in the babbit so far. I'm pulling the engine out this weekend. Once it's apart I'll have a better look.

PS why does this site keep logging me off when I try to post?
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aha. I misunderstood that you were going to line bore the old babbitt, and not repour it. Sounds good, as you will be left with babbitt that has proven itself to be strong. With the exception of the rear cap, which probably suffered from excess end play. Be sure to check the center main carefully for cracks...that one gets a lot of stress. Good luck, and sorry I have no clue why you are getting logged off
 
Thought I'd give an update. I pulled the engine and tore it down. Turns out no. 2cyl had a wrist pin let go at one time and a repair done. Bored out to max .125 with gouges still there. Also there is a crack from the center head stud. So I'm getting the block sleeved back to standard and the crack stitched. And then line bored to fit my other crank. Wasn't really planning on doing a major but will be all good when done now. It's amazing how forgiving these engines are. No one could get away with a repair like that on a modern engine. The engine actually ran quite well and no noticable blowby.
 

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J.C., if you got a .035 old crank, and a .025 thousandths New crank just polished out, your chance of making that work with out all new babbitt, is a very long shot, as you only have .005 thousandths wall to play with, and an Align Bore has to be put where it belongs, to come out with the center of the block, and the time Gear mesh, and you will probably, not have babbitt where it is needed.The rear cap you showed in pictures, has Lead Babbitt, and it has never been peened, so I am asuming the rest of the bearings were also not peened. Good Luck, Herm.
 
I agree with Herm, why do the job half aXXed if you have to go that far? Looks like you are in for either a complete rebuild or lots more laying under the car and pulling the motor.
 
Kohnke Rebabbitting said:
J.C., if you got a .035 old crank, and a .025 thousandths New crank just polished out, your chance of making that work with out all new babbitt, is a very long shot, as you only have .005 thousandths wall to play with, and an Align Bore has to be put where it belongs, to come out with the center of the block, and the time Gear mesh, and you will probably, not have babbitt where it is needed.The rear cap you showed in pictures, has Lead Babbitt, and it has never been peened, so I am asuming the rest of the bearings were also not peened. Good Luck, Herm.
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This is my first babbitt engine so forgive my ignorance when I ask - What is meant by peening the bearings? And how do you tell if they are or not peened? And the machine shop is measuring first to see if an align bore can be done.
 
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