Help identifying/fixing leak on perkins 4108

[LifesBetterWhenYoureBeating]

Hi folks,

I've just noticed a leak on my perkins 4108, and as usual it's in a place I can't even see. I managed to get a video of it (https://photos.app.goo.gl/doXyeA7ECSmJWP9b9) using an endoscopic camera and you can see drops from two different places close to (what I believe to be) the injector pump. At the 5s mark you can see one drop on the top center of the screen and shortly after that one from a different place right below it.

I'm not at all familiar with diesel engines, but every time I bring a diesel engine expert aboard they either say I need to overhaul the engine or that it's in great state - - one even said I needed to overhaul and within 1h changed his mind and said the engine is in great shape. So this time I'd love to try and figure things out on my own, with y'alls help, of course.

I suppose this video may not be enough to identify the source of the leak as it could be coming from other places and just forming the drops next to the injector pump. Any advice or suggestions on how to figure this out would be greatly appreciated!

Cheers,

[markxengineerin]

Hard to tell, but I would start by looking at a parts diagram and figuring out what the bolt/plug marked with green paint does. The only leak I saw (I only watched a few times) seems to be coming from there. If so, probably easy to remove + re-seal. Easy being a relative term depending on what you need to do to get access.

[LifesBetterWhenYoureBeating]

I've just found https://www.cruisersforum.com/forums...ak-236122.html and one of the drops seen on the video is coming from the same place reported in that post, the HP bleed Screw (identified in the attached pic). It's not the line fitting that's leaking as it is always dry

As suggested on that post, it's more common for a leak to develop in the thrust /stop levers, which would explain why I see drops from 2 different places. I'm going to look into that

Sent from my SM-A225F using Cruisers Sailing Forum mobile app

[LifesBetterWhenYoureBeating]

Originally Posted by markxengineerin

Hard to tell, but I would start by looking at a parts diagram and figuring out what the bolt/plug marked with green paint does. The only leak I saw (I only watched a few times) seems to be coming from there. If so, probably easy to remove + re-seal. Easy being a relative term depending on what you need to do to get access.

The drop you saw forms slowly, there's another one earlier in the video (seen around 1 o clock from the slow forming drop).

As I found from the photo on the other post, the green painted nut is the HP bleed Screw (or union?)

Sent from my SM-A225F using Cruisers Sailing Forum mobile app

[skipperpete]

You’re right , it’s a high pressure union, not a bleed screw. That connection only has injection pressure, not case pressure. It has no copper washers, just two special steel washers and the injector pipe joins it as a steel to steel connection. The best way to find the source of the leak is to completely dry off the pump housing with tissues or absorbent cloth then get a mirror and flashlight to observe with the engine idling.

[LifesBetterWhenYoureBeating]

Originally Posted by skipperpete

You’re right , it’s a high pressure union, not a bleed screw. That connection only has injection pressure, not case pressure. It has no copper washers, just two special steel washers and the injector pipe joins it as a steel to steel connection. The best way to find the source of the leak is to completely dry off the pump housing with tissues or absorbent cloth then get a mirror and flashlight to observe with the engine idling.

I've done that and indeed it seems like one leak source is the HP union and the other is a nut next to it (shown in the attached pic). All other parts on this side of the pump stayed dry while the engine was running. This new video shows the drops forming on the two nuts mentioned above: https://photos.app.goo.gl/BFhCfZCdrNvswfqs9

I'm not sure what to do next... Can I simply try tightening the nuts?

Also, I'm pretty sure these leaks aren't new; I've found then only now because I was inspecting things carefully after a filter change and bleeding, so I'm wondering what effect they have (other than a little lost diesel) given that my engine seems to run fine?


Sent from my SM-A225F using Cruisers Sailing Forum mobile app

[LifesBetterWhenYoureBeating]

I've counted the drops from both sources and they amount to around 16 per minute. I guess that's not enough to affect engine performance but obviously I still want to fix it. Maybe I'm better off hiring a professional to do it, though?

[ranger58sb]

Is it fuel, oil, coolant, or water?

(Discussion above suggests you're talking about fuel, but thought useful to pin down that factoid.)

-Chris

[markxengineerin]

Maybe I'm better off hiring a professional to do it, though?

Depends on the professional! Do you have a mechanic you like?
I don't think they'll do anything differently than you already are, but if you prefer to not get into the awkward positions, get dirty, etc, hiring is certainly an option.

If it were me, I would probably disassemble a lot of the area, and study all the sealing surfaces up close, after disassembly. If you find something that feels abnormally loose during removal, make it tighter and see if you fixed it. These types of connections do not need to be super tight- there should be a significant range between "tight enough to seal" and "so tight it's going to damage something" that isn't difficult to find if you have done other types of engine/machinery maintenance before.

You could also try strategic placement of those white oil absorber mats, or cut pieces of them, to narrow down the source. Fuel shows up as bright pink, hard to miss.

[skipperpete]

Originally Posted by LifesBetterWhenYoureBeating

I've counted the drops from both sources and they amount to around 16 per minute. I guess that's not enough to affect engine performance but obviously I still want to fix it. Maybe I'm better off hiring a professional to do it, though?

That’s too much leakage to ignore and since you’ve narrowed it down to the high pressure connection and the case bleed screw, I suggest you attempt the repair yourself. With the HP banjo on the hydraulic head, get the correct size socket wrench and a breaker bar and tighten that banjo bolt first, really tight! Then tighten the injector pipe, preferably with a single hex flare nut wrench. Then wipe it down dry and run the engine.
The case bleed screw is very delicate so first check the larger part that screws into the case for tightness, then with a small wrench , open and close the bleed screw to perhaps re seat it.... it’s brittle steel and will break if you overload it.... just nip it up. It’s possible that the tip of the bleed screw is already damaged or broken off. I just took this bleed screw out of the same pump and that’s a copper washer. The hard steel washers are on the hp banjo.
I’m having a real struggle with a leaking injector pipe right now, so far two attempts to stop a tiny leak have been unsuccessful so armed with a new flare nut wrench l’m hoping for 3rd time lucky today.

[markxengineerin]

I replaced all yanmar fuel related sealing washers with these during my rebuild

https://www.amazon.com/Hilitchi-180-...s%2C687&sr=8-3

No leaks. You don't need to tighten any of this stuff very much if parts are not damaged. Using a breaker bar on a banjo bolt sounds like a big risk- it's a hollow bolt with holes drilled in it! I have broken them in my younger days. Rubber conforms much, much better than copper or aluminum to any imperfections. I can't comment on durability, but I have a whole box of them on board if one starts to seep.

[skipperpete]

The 4 banjo bolts on the DPA pump are next level quality and take injection pressure, they need to be tight but yes , normally no breaker bar on banjo bolts, definitely agreed.

[stormalong]

[QUOTE=ranger58sb;3794421]Is it fuel, oil, coolant, or water?

(Discussion above suggests you're talking about fuel, but thought useful to pin down that factoid.)

-Chris[/QUOTE

I agree. From the color it looks more like water, not fuel. Put a paper towel under it and confirm what it is. If you were dropping that much fuel you would see it under the engine. The leak could be coming from an area above or next to the injection pump.

[LifesBetterWhenYoureBeating]

[QUOTE=stormalong;3794595]

Originally Posted by ranger58sb

Is it fuel, oil, coolant, or water?

(Discussion above suggests you're talking about fuel, but thought useful to pin down that factoid.)

-Chris[/QUOTE

I agree. From the color it looks more like water, not fuel. Put a paper towel under it and confirm what it is. If you were dropping that much fuel you would see it under the engine. The leak could be coming from an area above or next to the injection pump.

It's fuel