YM1610D #2 rod bearing

[tdmack-HT]

Engine would blowby extreme amount of smoke after running a few minutes. Noticed bubbles coming up in radiator making me suspect head gasket or cracked cylinder. I pulled the head to further investigate. I didn't find any definitive signs that the head gasket had failed but I'm not sure that means anything. Rocking the crankshaft a bit I find that #2 piston has a lot of end play (time to go underneath). I removed number 2 rod cap to find the bearing was hammered. It looked like it wasn't getting oil.
Although there was quite a bit of bearing material transferred to the rod journal it cleaned up pretty good.

Question: should I be able to see oil pumping out of all the rod journals when I spin the motor (head and pistons removed, pan installed full of oil) number 1 rod journal is squirting pretty good.

Is there a recommended procedure to test the lubrication circuit at this stage of assembly?

I just hate to reassemble the engine without verifying that all the rod bearings will get oil.

Tim

 

[winston-HT]

I would sure agree with your thinking. Something caused that rod bearing to fail. If you are seeing oil at one journal and not another I would certainly be suspicious. I do not have a drawing of the oil circulation path for the 3t75u, maybe Aaron can post it for you. I would think with the pan removed you might be able to use air to blow in at a journal and with plugging along the way confirm the air is making it's way the length of the crankshaft. Has you oil light ever came on?

 

[tdmack-HT]

I've not seen the oil light come on. It's operation is something that I need to verify. I should be receiving new .010 under rod bearings next week. I plan to reinstall #1 piston to stem the oil loss from that journal thinking I'm loosing so much there that I may not have any oil left to push on down the crank to the other journals. I might add that there is some oil just weeping from the mains while I spin the engine.

Like you say, that number 2 bearing went out for a reason.

Have the oil pumps been an issue on this engine, (900 hours)?

 

[winston-HT]

I have not read of oil pumps being a problem on these engines but would not put that out there with any authority. Did you micrometer your crankshaft to justify ordering the .010" under bearings?

 

[Aaron-HT]

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No.

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[tdmack-HT]

I only had calipers and couldn't take a measurement with any accuracy so I put plastiguage under a new set of standard bearings. That measurement showed about .011 clearance.
Seeing the diagram Aaron put up (thanks) is giving me a bad feeling about the #2 crank bearing.