Massive oil leak Yanmar 4jh2-te

[IsaakOker]

Hi everyone!

I’ve finally managed to finish the rebuild of my Yanmar but when starting it to test it, it fires up nicely but leaks a LOT from behind the governor.

It’s not the following:
1) oil filter as it comes from above
2) it’s also not the pipe and banjos going from block to FI pump
3) 4 caps on the engine block on that side
4) it doesn’t come from above the caps on that side either because what I can see from above and behind the Injection pump is all dry.
5) also doesn't come from pressure sending unit as it comes from above

To me, it looks like it’s coming from the bottom of the governor but the oil stream is a thumb size so it has to be a bolt that’s entirely loose or something.

I can’t access that side of the motor as it’s inside the engine compartment and can’t see from below but the governor and injection pump weren’t taken apart so there shouldn’t be anything loose…

Any help would be very appreciated!!

https://ibb.co/Hh72vWB
https://ibb.co/TqdHyW8

[skipperpete]

Glad to hear that you got your engine running again, well done. On the oil leak problem, I know you discounted the oil feed pipe to the injector pump but in your photo’s , if that’s it at the top of the pic it seems to be corroded quite badly under the paint and there’s a good chance it’s either snapped off or has a rust hole. Yanmar uses a similar thinwall tube on its 3GM engines and they fail fairly often purely because of that type of corrosion. Even a pinhole in that tube on your engine would leak a lot of oil.

[Bycrick]

That oil pipe that goes from the block to the injector pump is the work of the devil. I had the first one fail the night before making landfall in the Galapagos. The replacement one just failed. The third one (just received) uses a copper tube rather than a steel one. Here’s hoping …..

[skipperpete]

Don’t be fooled by the appearance, the GM series ones look like copper too but are still steel.... run a magnet past your new one

[ScottRhodes13]

There's also the oil pressure alarm sender. On the block at about the right height, but quite a bit aft of the area you're seeing the problem.

[IsaakOker]

Hii everyone!

Thanks for your inputs!!

I’ve narrowed down that it isn’t from the metal pipe surprisingly.

I’ve managed to have quite a good look while running the engine and it seems to be coming from the bottom of the governor-FI pump joint.

Now, on this engine, as I only have a few inches in that side of the engine room, it’s going to be hard to take the governor off without pulling the engine out again…


Also, maybe more worrying, the oil is now draining with a creamy color as if it had water in it but it smells slightly sweet so I’d say that it’s oil and fuel? (But that shouldn’t turn creamy I suppose)

Any ideas?
I’ve checked the oil in the sump through the dipstick and it’s crystal clear, not as dark as it was where it’s pouring out and also not creamy like it’s pouring now…

[IsaakOker]

Ok, new update!

It’s a tiny pinhole at the bend of that pipe after all.

I seriously don’t get why that pipe is run that way…

I’m going to attempt to jbweld it until the new one comes in which should be ina few days. Let’s see if it holds….

Any ideas on the milky oil? The only part of the engine I didn’t rebuilt that has a mix of water and oil is the lube oil cooler but it surprises me that water and oil could be mixing…

Engine starts up first crank and doesn’t smoke excessively, maybe a little white but not too much.

Dipstick comes out clean, no water what so ever…

Might have to drain a little from the sump to see if it’s really mixed with water or not…

[skipperpete]

You had me worried for a while when you proposed removing the governor housing, not an easy feat with the pump still in place. If it proves to be impossible to buy a new pipe you could get a motorcycle flexible brake hose with the right size banjo fittings, I recently did this on a 2GM Yanmar, it works quite well but I spent a bit of time finding one with 8mm banjo x10mm banjo.

[IsaakOker]

Sounds like an option…

I probably can order a genuine Yanmar pipe but it will probably be 50-100$ for a piece of metal with 2 banjos so I’ll try to jbweld it until I can find a good solution.

As for the milky oil, I’m completely confused because the head gasket is new, head gasket is new and the oil pan doesn’t show any sign of water but it did at the beginning of the leak come out clean, then dark brown (like old oil) and now milky and I was hoping that maybe the pressurised oil coming out was aerated and therefore milky but I think I’m dreaming 😅

Any ideas where to start with checks?

I'm going to wait till tomorrow and I fit the pipe back in as I currently can't really do much troubleshooting I think.

Coolant level has gone down but I just refilled it and had the engine running 1-2minutes each time for about 5 different starts as I was looking for oil leak. Suppose the coolant has to be topped up first as it's likely it's gone down because of filling the system.

Oil level hasn't risen, rather gone down but that's also normal because of all the oil that was pouring out so can't figure it out that way either...

Anyways, any suggestions would the appreciated as always! 🙂

[skipperpete]

Here’s the flex hose

[IsaakOker]

So, just an update:

The patch in the pipe proved that the leak came from there so now I’m going to try and get a permanent replacement if that part.

As for the water in oil, I’m going to start a new thread as I think it’s easier for other Yanmar owners to make use of the thread titles ! 😅

Basically yesterday when running the engine with the broken pipe for the last time the oil started to flow creamy but the oil pan didn’t appear to have any oil in it when checking the dipstick but I’ve just ran the engine for 2-3 minutes and now the dipstick as traces of water although nothing foamy yet.

Thank you all!

[Bycrick]

SkipperPete — You’re right. The silly pipe is still steel, but this time, instead of painting it grey, they’ve plated it with copper. You caught me being credulous and believing my lyin' eyes.

[capt jgw]

I've had a couple custom hose assemblies made by West Michigan Rubber, a local industrial hose shop here in Muskegon. There are similar shops most anyplace. They can put whatever fittings you need on a piece of hot oil rated hose.

[glenn.225]

I've had good luck at Hydraulic shops getting this type of hose made up . Usually very inexpensive compared to OEM. And of the hose is oil resistant.