Yanmar 3YM30 Oil Flow Static Test ?

[DougnJoy]

Hi there all you mechanics with the "tricks of the trade"......
........I have just reassembled my Yanmar 3YM30 after being drowned and stripped right down with new parts and reassembled. I notice after a short test run the timing gears are still dry and assume the oil might not be getting right thru the engine (even tho I tested all the galleries)
Is there a static test method to assure full oil flow to all the right parts and bearings without starting the engine (don't want to chance running bearings dry)- maybe pump oil thru somehow.
I figure I could disconnect various items to check flow (Injector pump oil line- oil gauge sender hole, rocker cover – where’s the hole for the timing gears) I’m sure I assembled all the bearing metal oil holes correctly by the manual
Thanking you for any advice
"Drowned Donk"..........

[Dieseldude]

Hello DougnJoy,

Large diesel engines are equipped with a prelube pump that provide a means of circulating oil independent of the engine’s stock oil pump. There is only one convenient means I can imagine to add one to your Yanmar. Auto enthusiasts often add a bypass oil filter. Kits are available from performance auto suppliers. Amsoil also markets them. A web search should show you some suppliers. You just have to find a kit that is compatible with your Yanmar filter dimensions and threaded base.

In case you are not familiar, a bypass filters is a filter with finer media than stock filters that operates in parallel with the stock filter. The kit has an adapter that screws into the stock filter base with plumbing that facilitates tapping into the lube system. Instead of the bypass filter, just connect an external pump, and you have a means of circulating oil without running the engine. I’ve never tried this, so I do not know what kind of pump to suggest. Perhaps one of those pumps that is used for draining the sump for oil changes by way of the dip stick tube. I would expect that this kind of pump should not over pressurize your lube system. However to be sure, do a test before connecting it to your engine. Put a pressure guage on the pump discharge and run it against a load such as a partially opened quarter turn valve to see how much pressure the pump will produce. Tweak the valve from full open to almost closed while watching the guage. The first time you try running the pump connected to the engine, also watch the guage. If too much pressure, the first few seconds, STOP. Over pressuring could destroy seals and rip the media of your stock filter. Oh, I just thought of a problem with trying to suck oil through the stock pump with it sitting idle. This is not likely to work since the stock oil pump is likely a gear pump and you will have little success getting oil to flow past the gears.

Alternatively put your external pump suction directly into the sump through the dipstick tube and cap off the suction port of the bypass filter adapter. This set-up would provide an oil flow path independent of the stock pump. Of course be sure and get the pump flow direction correct. To get oil well distributed, you might need to turn the engine as the oil is pumping. Large diesels have a turning gear for this. The only simple means I can think of is to turn it briefly, using the starter and with fuel supply to the engine disabled so that it cannot start. Of course you were concerned with damaging bearings by running the engine. I’m sure that you re-assembled the bearings with a lubricant, so this low speed turning should not cause any harm.

It’s a somewhat elaborate set-up with some expenses, but the only means I can think of to get some oil pumping through an engine that’s not running and that is not equipped with a stock prelube pump. Once you have your engine back to normal, you can install the bypass filter and perhaps get extended service life from your oil and engine.

Have fun with your project,
Dieseldude