Yanmar 3GM30F injector question

[SalishAire]

When we owned our Nordhavn the "wing" (AKA emergency) engine was a Yanmar 3GM30F. I looked into servicing the injectors and found information about cleaning them and a description of the tips explaining why they had an inverted cone shape. When I looked at mine I couldn't even tell the shape until I scraped some serious carbon deposits loose. The outcome was a much more smooth running engine.

Skip ahead to purchasing Hyacinth our A25 which also has a Yanmar 3GM30F engine. I pulled the injectors on it and cleaned them but they do not have the inverted cone tips (just a standard straight sided design). I have wondered if the injectors in this engine are after market ones, or if Yanmar changed the design at some point, or ???. So far I haven't found a clear answer.

Since I found cleaning the ones with the inverted cone shape did seem to make a difference - if these are supposed to be of that design, I am hoping to find OEM injectors to install IF that is what should be in the engine.

QUESTION: Are there any 3GM30 gurus on the list who might shed some light on this???

[WillieC]

Drop in, maybe after a call, to Tacoma Diesel? Find the expert there?

https://www.tacomadiesel.com/

[DesertAlbin736]

Norman & Clarice,

Well, as you know, La Dolce Vita is also powered by a Yanmar 3GM30F. Current hours on the meter are 1,274, of which 737 hours have been added by us since taking ownership in March, 2014 when the meter read 537. I believe from PO records it had approximately 2,500 hours before the current meter was installed. Things have been a little slow since COVID. In the past 12 months we've only added 19 hours on the meter. In the first 10 months of 2021 we added 46 hours, mostly on the aborted Erie Canal cruise. 2020 was a nothing year with COVID. So total hours since installation around 1990 may be somewhere in the neighborhood of 3,775 or thereabouts, probably more. Anyway, the engine has always run well & doesn't smoke more than a little grey puff on startup. So aside from doing regular PMs, being anal about clean, fresh fuel, and putting those hours on it, I haven't had the need or occasion to mess with the injectors or pump.

Fall is pretty much prime boating season here in AZ, but some outside non-boating interests (email me or do a PM if you want to hear about that, I'd rather not go into it here) have preempted all boating until just last week, along with a fuel tank overhaul project that took a lot longer to finish than expected. That project was to cut in cleanout ports in the tank & fabricate mounting rings & cover plates from 11 gauge s/s plate, which I just finished today but still have to clean/prep/paint the bilge area underneath where the tank goes before I can re-install the tank & get things running again. I have progress photos on my phone & when I get some more free time I'll download those to my desktop & do a topic on that endeavor. Suffice to say, the inside of the tank is now as clean & shiny as the day the boat left the factory. And yes, the factory mid-tank baffle is still securely spot welded in place. One thing I plan to do when I refill the tank is document exactly how much fuel is in the tank at each gauge reading from bone dry to E, 1/4, 1/2, 3/4, & Full. My gauge float bottoms out about halfway up the sloped part of the tank about 2 or 3 inches above the true flat bottom section. From the looks of it anything less than 1/4 on the gauge could tip the fuel away from the pickup tube enough to stall & airlock the engine at 10 to 20 or more degrees heel.

I'd be interested to hear how your efforts go. Except for the past few weeks while the tank has been in my workshop I usually try to hookup my hose & bucket rig & run the engine for a bit at least once a month when we're not able to be out on the water.

If you do your RV thing down here this winter stop by & say hi sometime.

Steve E.
"DA"

[Burton]

As to cleaning, our area has a place that specializes a lot in cleaning injectors with ultrasonic equipment, and they rebuild them, too. The PO had the Yanmar 3JH3E (just about 105 hrs on it) so lugged down with the wrong prop the injectors were horribly carboned up— some of the worst the shop had seen. One broke its holder and popped out! Back to harbor on two cylinders.
(That’s how we learned how bad they were). Looking at replacements, much cheapy Chinese stuff is out there. Anyway, we got a manual download from Mack Boring or whatever the importer’s name is, and I imagine you can get one for the 3G and see what you can figure out. The manual is huge, quite detailed for total rebuild.

[SalishAire]

injector tip image.jpg

Image of inverted cone Yanmar injector tip from Yanmar repair manual.