Yanmar 2GM20F Fuel Injection Pump Leaks!

[mz4wheeler]

[Please see attachment photo]

My 2GM20F fuel injection pump is seeping diesel when the engine runs. It is not that excessive, but enough to make things reek of fumes. This has been going on for quite a while and I temporarily fixed it by re-seating #12 a while ago. Well, it is back, worse than before.

Without taking the whole thing to a shop for a rebuild (sailors are frugal), I was hoping that someone has experience taking these things apart enough to assure me that if I remove #12, parts won't spring all over my engine compartment [grin].

According to the parts diagram:

#13 is an o-ring (I'm hoping THIS is the issue)
#10 is a gasket
#6 is a gasket

Questions:

1) Can I safely remove #12 and replace the o-ring (#13)?
2) Can I also replace #10 and/or #6, or are these integrated into the plunger

My goal is to just stop the leaks. Other than this, the engine runs perfect.

Thanks!

 

[kloudie1]

MZ, the o-ring (13) is the seal that is leaking unless there is a crack in the body of the pump or the big top nut (delivery valve spring holder). Make sure the leak is not between the top tapered fitting on the delivery tube. The O-ring, #13 can be replaced by removing the fuel line from the top, then slowly backing out the "spring holder" #12.. The spring should release before the threads come undone so there should not be a "sproing" (spring pops out and flies through the ceiling, never to be found again) The pressure the o-ring sees is full injection pressure, so once it starts leaking, it will be cut by the escaping high pressure fluid. That o-ring is a specific material and hardness, so I wouldn't use one except from Yanmar or a reputable diesel injector repair shop. That job must be surgically clean to not cause damage to the pump.. clean off everything in the area before beginning and have clean rags ready to cover to keep any dust or debris out.. Let us know how it turns out !

 

[mz4wheeler]

MZ, the o-ring (13) is the seal that is leaking unless there is a crack in the body of the pump or the big top nut (delivery valve spring holder). Make sure the leak is not between the top tapered fitting on the delivery tube. The O-ring, #13 can be replaced by removing the fuel line from the top, then slowly backing out the "spring holder" #12.. The spring should release before the threads come undone so there should not be a "sproing" (spring pops out and flies through the ceiling, never to be found again) The pressure the o-ring sees is full injection pressure, so once it starts leaking, it will be cut by the escaping high pressure fluid. That o-ring is a specific material and hardness, so I wouldn't use one except from Yanmar or a reputable diesel injector repair shop. That job must be surgically clean to not cause damage to the pump.. clean off everything in the area before beginning and have clean rags ready to cover to keep any dust or debris out.. Let us know how it turns out !

Thanks a lot kloudie! I just wanted to make sure that if I remove #12, things won't either fall out (or worse, IN) the engine. BTW, the best way I have found to really clean an area of an engine is a can of brake cleaner. Evaporates in 30 secs. I'll be sure to report back in on how it went.

 

[Sailm8]

I had the same leak and the O rings fixed it. If that gives you any piece of mind.

 

[mz4wheeler]

I had the same leak and the O rings fixed it. If that gives you any piece of mind.

Yes, it does. Thanks!

 

[mz4wheeler]

Let us know how it turns out !

Just a follow up on this job last September. It went smooth and no issues. I took a couple of photos, but none on the completed job. Hint: Brake cleaner, along with a wire brush did a fabulous job cleaning the area. It cleans and evaporates almost instantly. I replaced both o-rings and it hasn't leaked since. For the first time since I owned this boat, the engine doesn't leak anything. Someone once told me "all diesels leak"... Not true.

 

[woodster]

Someone once told me "all diesels leak"... Not true

they only mark their spot

 

[Ken13559]

All diesel leaks at some point in time. You just need to "find small, fix small" else it becomes a "found big, BIG fix".

 

[Jimmymak]

Hi guys
I’m about to order the replacement o rings, however I wanted to ask- is it sensible to replace all 3 o rings at once ( I’ve got a 3GM), or just do one when a leak appears?

 

[kloudie1]

Might as well do all three.. Once you have it cleaned up, replacing the o-ring is not that big of a deal..
Welcome to the forum, Jimmy.. good luck with the repair..

 

[Jimmymak]

Thanks mate much appreciated . I think I knew the answer to my question as I was typing it . I also have a hunter 34 (well 336) by the way. Great boat

 

[RoyS]

This is from memory: The part numbered (12) must not be over torqued as it will distort the delivery valve. No.12 should be torqued to spec. (which I forget) and held from turning further when connecting the pipe to it. Keep in mind (10) is sold as a lapped unit and must be kept that way. Good luck.

 

[Charles Erwin]

29 - 32 ft lbs. Check for smooth movement of the rack whilst you tighten the delivery valve fitting. Important to do these one at a time so you cannot intermix parts - as already pointed out by RoyS. Check also the output tubes to verify the ends are polished and defect free. These can leak - the fuel seeps down to the holder threads and makes you think the pump is leaking when it is actually a corroded output tube end.

Charles

 

[Jimmymak]

Thanks guys great advice! Will keep you posted on how I go

 

[MitchM]

thanks to all who posted. the information above from these knowedgeable mechanics like Kloudie and roy and Charles is invaluable and is worth $$$$$$ to us shoestring budget people. my o ring is NOT leaking but i will sure keep this thread handy in my 'online boat maintenance' section for yanmars. ' Q: how many hours on the enigne when these o ring leaks start showing up ??

 

[Jimmymak]

Hi Mitch
Yes my 3gm30f is nudging 2000 hours. Not sure if the previous owner/s had this issue before but it’s only on one tube... so far! I’m going to replace all 3 o rings to hopefully get me another 2000 hours

 

[Jimmymak]

Hi guys
Just an update to say the o ring replacement went pretty well!! I replaced all 3 and the engine is back online . Only issue I found was trying to keep foreign matter out of the top of the injector pump once the delivery tube holders are out. If I had my time again I would use gaff tape or similar to cover the exposed holes. Thanks to everyone for your help and advice it’s much appreciated

 

[kloudie1]

Good to hear, Jimmy !

 

[sailsanjuanbay]

In my case, I've been getting air in the fuel lines, causing the engine to stop. I've been bleeding air underway for 2 years!! The information posted has been very valuable and really saved me of buy a new $1,200. new fuel pump, (that was a mechanic recommendation). Thanks to all.

 

[mike cunningham]

Man, was this topic helpful. I had been experiencing a leak in the vicinity of the top of the hi pressure pump for 18 months. It had been getting increasingly worse. The problem was 1. It was hard to determine exactly where the leak was and 2. The top of the pump is hard to get to unless you disassemble raw water side of the cooling system tubing which surrounds the pump top area. I finally got serious and started with a gogle search which landed me on this topic. I removed the tubing and pulled the injector feed pipes. First I tried reinstalling these hoping the leak was coming from a loose connection. I had replaced injectors a while ago and that activity places a little stress on the tubes. No joy.
By the way, I tested by setting the decompression levers and rotating the engine by hand. When I shone a bright light at the top of the pump I had thoroughly dried off, I could see the seepage of fuel start at the base of the retainer nut. I then pulled the nut as per OP and found the o ring badly cracked and degraded. Finding this, I quickly decided to replace both of them (2gm20f) and sure enough, the other one was in the same condition when I pulled it. If you run into this problem I would strongly suggest swapping out all of the o rings.
So I should be receiving the rings tonight via UPS and will update with results when I install tomorrow.