Yanmar 1GM10 diesel problems

[druid]

Rule of Thumb: Yanmars (especially older ones) are a PAIN to bleed! Took the mechanic over 2 hrs to bleed my 2QM20 after I gave up. I suspect sitting for a while got the air in all one place and it finally bled out.

And the decompression lever is used so you can crank (and crank, and crank!) the engine when you're bleeding it.

druid

 

[Alan Gomes]

Rule of Thumb: Yanmars (especially older ones) are a PAIN to bleed! Took the mechanic over 2 hrs to bleed my 2QM20 after I gave up. I suspect sitting for a while got the air in all one place and it finally bled out.

And the decompression lever is used so you can crank (and crank, and crank!) the engine when you're bleeding it.

druid

I don't know anything about the 2QM20, but the 1GM engine is not at all difficult to bleed. In fact, I just did it this morning after having my injector serviced at a nearby shop. The shop manual gives the procedure.

There is a little lever on the fuel pump that you work to bleed the line at the on-engine filter and at the injector pump. The third location (which typically does not need bleeding) is where the line goes into the injector. I had to bleed that one as well because I had removed the entire injector for service. After bleeding the first two locations I was able to get the engine to start, but there was still a little air in the line, between the injector pump and the injector. With the engine running at a significant RPM (e.g., around 3000), I cracked the high pressure line just enough to let fuel (and the air) spit out. (If you crack it open too far the engine will just die, so you just have to find the sweet spot.) Then tighten the line and you're good. It took me nowhere near 2 hours to do this. Maybe the 2QM20 is different but the 1GM is no big deal.

 

[druid]

I also had problems with a 2GM20F. At least for the 2GM, if you followed the procedure to the letter (ie systematically going through EVERY bleed point (5 iirc), including all the injectors, in the proper order) it would be OK. But iirc the problem with the 2QM was that the return line went to the filter rather than back to the tank. This meant the air was circulating round and round, and it took a LONG time to figure that out.

But compare that to my new Beta 25: crack the bleed point on the filter, wait for the bubbles to disappear, and... that's IT!

druid