Need 2nd opinion: Cracked piston ring in a Y2GM20F?

Nov 22, 2011
1,192
Ericson 26-2 San Pedro, CA
There's a new wrinkle in the situation: When looking over the engine this morning, I discovered the oil level is way over the end of the dip stick, even though I'm almost certain it was right on the mark the last time I checked. I've read that white exhaust is associated with unburned fuel, often from bad injector(s), and this can dump enough fuel into the cylinder to get into the crankcase, diluting the oil and raising the oil level on the dipstick.

This summer I sent both injectors out to a diesel shop to be rebuilt. It was after this that I first noticed the smoke (before that I was trying to fix a very strong, almost overwhelming exhaust odor, but no visible smoke at that point). I assumed the injectors were "fixed" after the rebuild, but is it possible they were somehow rebuilt incorrectly? Or when I subsequently had the injector pump rebuilt, is it possible that the pump wasn't properly calibrated with the injectors?? Really don't know what I'm talking about here, but I'm assuming the pump and injectors have to be precisely coordinated to ensure the correct fuel mixture...??

odaydokay: Thanks for the link...a good article, exceptionally clear in listing all possible causes by smoke color. And I like the illustration of smoke color. After seeing this, my smoke is clearly white, not blue as I thought it might be.
I just now noticed this post. If you are dumping fuel into the crankcase, the first thing I'd suspect is the diaphragm on the mechanical lift pump. This is a well-known failure point.

The good news is that if that's the culprit, the fix is easy and not very expensive. Simply install an electric fuel pump wired to your ignition switch, disconnect the hoses from the lift pump, hook the hoses up to the new electric pump, and call it done. (Of course, you also will need to do an oil change--obviously.) My 1GM has such a pump (it might even be the identical pump?), and I didn't wait for the diaphragm to fail: I replaced it with an electric Facet pump. With some minor changes to the plumbing, you can also set it up to bleed your engine after filter changes with the flick of a switch. I can provide more info on that if you are interested.

Here's a discussion on the Ericson list that you might fine helpful.
 
Nov 22, 2011
1,192
Ericson 26-2 San Pedro, CA
I just now noticed this post. If you are dumping fuel into the crankcase, the first thing I'd suspect is the diaphragm on the mechanical lift pump. This is a well-known failure point.

The good news is that if that's the culprit, the fix is easy and not very expensive. Simply install an electric fuel pump wired to your ignition switch, disconnect the hoses from the lift pump, hook the hoses up to the new electric pump, and call it done. (Of course, you also will need to do an oil change--obviously.) My 1GM has such a pump (it might even be the identical pump?), and I didn't wait for the diaphragm to fail: I replaced it with an electric Facet pump. With some minor changes to the plumbing, you can also set it up to bleed your engine after filter changes with the flick of a switch. I can provide more info on that if you are interested.

Here's a discussion on the Ericson list that you might fine helpful.
By the way: There is no need to remove the old lift pump or even to cap off the in/out ports on it. Just leave it on the engine but with the in and out hoses moved to the new electric pump. You can, of course, remove the now-unused pump and fabricate a cover plate to cover the hole if you want to for some reason. But there's no need to do that at all. Just leave it in place but disconnected.
 
Last edited:
  • Like
Likes: Whatfiero1
Jul 5, 2011
702
Oday 28 Madison, CT
There's a new wrinkle in the situation: When looking over the engine this morning, I discovered the oil level is way over the end of the dip stick, even though I'm almost certain it was right on the mark the last time I checked. I've read that white exhaust is associated with unburned fuel, often from bad injector(s), and this can dump enough fuel into the cylinder to get into the crankcase, diluting the oil and raising the oil level on the dipstick.

This summer I sent both injectors out to a diesel shop to be rebuilt. It was after this that I first noticed the smoke (before that I was trying to fix a very strong, almost overwhelming exhaust odor, but no visible smoke at that point). I assumed the injectors were "fixed" after the rebuild, but is it possible they were somehow rebuilt incorrectly? Or when I subsequently had the injector pump rebuilt, is it possible that the pump wasn't properly calibrated with the injectors?? Really don't know what I'm talking about here, but I'm assuming the pump and injectors have to be precisely coordinated to ensure the correct fuel mixture...??

odaydokay: Thanks for the link...a good article, exceptionally clear in listing all possible causes by smoke color. And I like the illustration of smoke color. After seeing this, my smoke is clearly white, not blue as I thought it might be.
You are most welcome. Anytime I see an event or situation that has changed for the worse I always ask myself first "What changed" especially if the item has had a reliable history. This goes for stereos, lawnmowers, you name it. It is remarkable how often (maybe 75+%) it turns out to be exactly what changed turning out to be the cause, so yes, have a good look at the injector repair issue. Maybe they used the wrong parts.....
 
Jan 30, 2012
1,123
Nor'Sea 27 "Kiwanda" Portland/ Anacortes
......
Lots of gumboot mechanics out htere who can cost you a fortune and do nothing but make it worse.
.......
There is only one moto in our shop ---

"We promise not to make it worse"

And we keep that promise too.

A rising oil level means there is a diesel leak into the crankcase. The usual culprit is the lift pump - the one mounted on the motor. It has developed a leak which leak allows diesel to pass into the crankcase. A high pressure pump leak to the crankcase would be the next suspect .

Either way - the central point - solve this fuel in crankcase mystery first.

Charles
 
Last edited:
May 15, 2015
131
Marlow-Hunter 31 Everett, WA
Seems like the list of bad to awful possibilities is endless. I do trust the mechanic who rebuilt the injector pump and who will be going over everything again on Monday. Not sure if he's Yanmar trained, but he has over 40 yrs experience as a dedicated diesel mechanic (boats and semi-trucks) and he's honest. He plans to check the oil for fuel--though I don't know how he does that at dock side.

I'll be sure to report back on the ending to this story--at least I hope the end is near.

Thanks, Matt
 
Aug 1, 2011
3,972
Catalina 270 255 Wabamun. Welcome to the marina
Hey @Ralph Johnstone , we can get you a great deal on a nice little Westerbeke if you want people to hear you coming on the other side of Bowen Isl.
 
May 15, 2015
131
Marlow-Hunter 31 Everett, WA
As promised, some follow-up: My mechanic did a thorough inspection last week and found several problems. In order of the attached images, he found:
-what appears to be long-standing leaking around one of the head bolts;
-fuel leaking from the injector holder (or case? not sure what it's called)
-fuel leaking from the bottom of the fuel pump, which was replaced about a year ago.

In addition to fixing these issues, he still thinks the piston rings need to be looked at and I agreed. So tomorrow the engine will be pulled and taken to his shop. As I said before he's a honest guy, he's not charging me for any of the work he's done so far...the clock starts tomorrow when he lifts the engine. So I suppose it could be worse.....

Matt
 

Attachments