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Old 30-05-2023, 10:27   #1
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Water in oil after Yanmar 4JH2-TE rebuild

Hii again everyone,

So yesterday I fixed an oil leak and today found water in oil so for you following along, this is a never ending story 😅

The engine runs very smoothly so I’m excluding head gasket issues also as I just redid it during rebuild and the engine hasn’t run longer than 5 minutes at a time since I rebuilt it(due to the oil leak that has been fixed).

The coolant level stays the same but again, a 5 minute run isn’t very long… & as the head gasket isn’t blown it shouldn’t mix anyways…(and the level stays EXACTLY the same)

The water pump">raw water pump shaft or the oil lube cooler are currently my thoughts but what would you check first?
Idon’t want to pump all the oil out , change the raw water shaft seal and find that I have to change all the oil again and do the oil lube cooler…
Any way to exclude one of the Teo?

Currently I haven’t managed to get the instrument panel to work so I don’t want to run the engine too long at a time as I don’t

Water comes out of exhaust just fine, slightly white smoke…

would you drain the oil through a dipstick pump out or better open the banjo but at the bottom of the dipstick ? (Suppose a pump out doesn’t clean it enough…
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Old 31-05-2023, 11:26   #2
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Re: Water in oil after Yanmar 4JH2-TE rebuild

It's not the raw water pump. Any raw water that gets past the seal drains out a hole under the middle section of the pump before it gets to the oil seal.

First, I would try to identify whether you're seeing raw water or fresh water. I don't know if you can tell that visually, but an oil analysis ought to identify it.

If it's raw water, I think it must be mixing in the oil cooler. If fresh water, I guess it must be the head gasket. I think I've seen some posts where people suggest the exhaust manifold gasket, but I don't know about that. Some people might suggest the turbocharger, but there, the coolant runs through the turbine chamber which is separate from the main body where the oil flows.

Mostly I'd suggest that you run the engine for a while to make sure you really have a problem. From your description in the thread about the oil leak it sounded like you're just seeing traces at this time.

I've found the best way to drain oil from that engine is to clamp a 1/2 inch hose over the end of dip stick tube and pump it out. Just make sure to push the hose down far enough to cover the little vent hole. The dip stick tube enters the oil pan at its lowest point so you're not going to miss much. I think that's more reliable than trying to push a small diameter hose down the dip stick tube and trying to go far enough without going too far.
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Old 31-05-2023, 11:47   #3
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Re: Water in oil after Yanmar 4JH2-TE rebuild

Quote:
Originally Posted by ScottRhodes13 View Post
It's not the raw water pump. Any raw water that gets past the seal drains out a hole under the middle section of the pump before it gets to the oil seal.
Unfortunately, not entirely true. Yes, these pumps have a weep hole. Some have a very large one, some only a small one. The small ones can get plugged with salt. I know of at least one engine that had it happen.

So, while less likely, still worth checking, although with a recent rebuild maybe even less likely.
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Old 31-05-2023, 16:24   #4
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Re: Water in oil after Yanmar 4JH2-TE rebuild

Well it’s been a long haul for you with the seized solid 4JH2-TE and after 4 years doing the overhaul you’re almost back to the starting point..... water entering the engine from an unidentified leak. Did you eventually get the seized injector pump rebuilt or did you manage to free it up yourself? How much corrosion was there on the crankshaft when you did the bottom end? Did the turbo survive the 9 years of inactivity or did you overhaul it ?
I really hope the rebuild has a happy ending and you get a few years of trouble free engine use.
After seeing your photo’s of the damage in your 2019 OP , (just the cylinders alone) I would have written that engine off as an economically unfeasible rebuild .....so, well done with getting her back to life.
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