Yanmar ym3810d and 336d. I built one engine out of the two. New Rings and rod bearings new gaskets seals did valve job on head. Ive done probably a hundred different overhauls but never a 3 cylinder yanmar. My problem is no oil pressure. I'am hoping someone here may know what could cause this. After completing the overhaul I primed fuel system and it started right up and ran good. After starting I quickly looked at my oil gauge as I always do and no pressure. I checked gauge on something else and it works fine. I thought well maybe oil pump is bad since the other block had a rod through it and I was not sure which of the 2 oil pumps I put on the new motor. Took front cover off and put other oil pump on. Dropped pan and checked rod bearings just to make sure they hadn't been hurt and checked rod orientation thinking maybe I had them in backwards, grasping at straws. Only ran engine for a couple minutes. I went ahead and re lubed the bearings with engine assembly oil re torked and this is where I am now. Just don't see any reason to not have oil pressure. Any comments or suggestion is appreciated. Can the main bearings be installed wrong? Maybe block a oil passage.? I blew through oil holes on crank jornals. Everything seems open.
oldnslo
Super Member
Can you remove the filter and figure out some way to pump into the filter nipple with out the engine running to see if you build any pressure. You would need to be careful since I am not sure which side of the filter the relief is on.
This way you can start to isolate where flow is going without risk of damaging the engine.
This way you can start to isolate where flow is going without risk of damaging the engine.
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oldnslo
Super Member
Sully
Other option might be to feed oil into the fitting for oil pressure. This would backflow to the filter but still might provide a little insight on where the oil is going.
Other option might be to feed oil into the fitting for oil pressure. This would backflow to the filter but still might provide a little insight on where the oil is going.
Tinhack
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^^^ This. Use an old grease gun filled with oil and tube facing up. The hose thread is probably the same and you can feel any resistance if there's a blockage. The oil pressure gauge is typically on the main oil gally.
I use an old grease gun like this with Way Oil to lube my Bridgeport Mill. I sealed the plunger end cap since that's all I use it for now. I keep it filled with oil.
I use an old grease gun like this with Way Oil to lube my Bridgeport Mill. I sealed the plunger end cap since that's all I use it for now. I keep it filled with oil.
Pump was not setting very long. I put substantial amount of the sticky engine lube in the pump gears thinking that might help prime the pump.
Thanks, will try this.
Great group of guys, especially like the thinking outside the box. Must be some MacGyver DNA in the bunch. As for me just a little slow on getting back to the tractor. I have it ready to test again but have to take care of some mowing first. At 76 years young and 100 degree South Texas heat it is like working in a sauna down here. Thanks again for all the help...
California
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I would try just about anything, before cranking the engine again with no oil pressure.
You might try injecting oil, or just air, wherever you can to see if it's blocked or leaking out somewhere. Maybe make adapters (or rubber nipples) to put oil under pressure into the oil gauge fitting, into the center of the oil filter mount, into the fitting for the exterior oil line that goes up to the valve train if your model has that.
Or pull the oil pump and inject oil there as a substitute for a bad pump.
Anything but crank the engine dry.
You might try injecting oil, or just air, wherever you can to see if it's blocked or leaking out somewhere. Maybe make adapters (or rubber nipples) to put oil under pressure into the oil gauge fitting, into the center of the oil filter mount, into the fitting for the exterior oil line that goes up to the valve train if your model has that.
Or pull the oil pump and inject oil there as a substitute for a bad pump.
Anything but crank the engine dry.
Using Shell T4 Rotella 15w40 Diesel enging oil. Thanks for the tip. I try to stay out of heat as much as possible but you know how that goes.
Going to try that in the Morning. Thanks for the help California. Met my wife in Oceanside California. Married in 1969, 55 years later still got her.
bmaverick
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YIKES. We are told not to use 15W40 in Japan made to JIS standards diesel engines. It traps the heat in. The heat takes longer to dissipate. 15W40 is fine for American iron tractors or that era as those are made to SAE with larger oil passages in the engine.
10W30 summer, unless it's over 86F, then straight 30.
I use the Rotella 10W30 T4 diesel.
rScotty
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I now use lighter viscosity oils like 5w-30, but used 15w-40 for 50 years in diesels of all types and never saw any wear or problem due to oil. I do warm my machines up before using them.
Back to the oil pump, engine oil systems are relatively low pressure. That is why their filter is in the oil pressure side of the pump rather than on the suction side like hydraulic power pumps.
There is no reason why you cannot wire in a small 12 volt & 30 psi electric pump and use that for troubleshooting the lubrication instead of risking your irreplaceable diesel engine. You could even run with the electric pump.
Also add a couple of pressure gauges so that you can see if the problem is blockage or lack of fluid.
Back to the oil pump, engine oil systems are relatively low pressure. That is why their filter is in the oil pressure side of the pump rather than on the suction side like hydraulic power pumps.
There is no reason why you cannot wire in a small 12 volt & 30 psi electric pump and use that for troubleshooting the lubrication instead of risking your irreplaceable diesel engine. You could even run with the electric pump.
Also add a couple of pressure gauges so that you can see if the problem is blockage or lack of fluid.
Tinhack
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Are you new to South Texas?
It's like this every year. The really hot weather doesn't get here until later this month and through August into September. I'll be 74 in October. I'm looking forward to Winter when it drops down to the 50s and 60s. 
Thanks for the ideal. I'am still in the field mowing but will get back to tractor tomorrow. Thanks again...
