Yanmar Newbie. Finally success

DrB · #1 04-27-2008

We splash on Thurdsay, so Yesterday was paint day and today was re-energize the "Iron Sail". We have a Yanmar 30GM Freshwater cooled model (27 hp). I ahve never changed the filters on our engine as this is the first year we have had her. Changed the oil last winter before we put her away, but today was fuel filter and water/fuel separator day.

Reading the engine manuel, input from a bunch or others, and finally a step-by-step tutorial by a Yanmar mechnaic I got it to re-fire.

The Water Separator/Fuel Filter was straightforward, but the Engine Filterr was a PITA. I filled the fuel filter cup as much as I could when I changed it, then screwed it on. However, I tried to use the hand fuel pump lever to pump the fuel/bleed the air, but it didn't seem to be moving the fuel at all. I pump almost a hundred times, but still nothing out of the top of the filter unit. I got frustrated so I removed the top screw and dripped in fuel with a disposal pipette until it was filled to the brim. Then I screwed the screw back on.

Do I have a bad hand pump or does it move only a frew drops at a time? Once the engine started it was a little rough, but then smoothed out nicely. I pumped about 5 gallons of water out of the exhaust, which took about 4 minutes, repeated and then shut her down. All guages and pressures looked normal.

Once when that engine ran smoothly i yelled out "It's Working!!", like young Ankin Skywalker did when he finally got his POD racer working in the Star Wars/Phantom Menace.

DrB

MedSailor · #2 04-27-2008

Congratulations on your success! I am a former Yanmar owner myself (2qm20 which is just like the GM series but a little older).

About your success, I would advise you to be cautious when you splash. I have never seen or heard of someone changing both fuel filters without getting air into the system first. I've been told it can be done, but I don't believe it.

If I were you I would work on the assumption that you have air in your fuel system now until you've run the engine for 10-15 minutes. I still remember the first time I changed the filters and bled the engine. I was elated that I did it successfully without bleeding as it started right up, but after 5-10minutes of running it shut down. It had run for those minutes with the fuel in the lines between the filter and the high pressure fuel pump.

You could either run your engine for a while with a few more buckets of water, or if it's a short motor to your slip you could just leave it till you get there. I'd be wary though of taking her out somewhere without further testing.

As for the lift pump, the mistake I made once was not pushing the lever down enough. It seemed like it should be working when I was pumping it but you need to press it down until it's nearly vertical. Once someone told me this, and I pushed through the extra resistance it was an "ah-ha" moment. Another problem is that sometimes the lift pump lever won't work if the flywheel is at a certain place. Rotate the flywheel a 1/4 turn by hand and pump some more.

Lastly, if you install the O rings wrong on either filter they can sometimes obstruct the flow (done that one too) and cause the lift pump to not pump at all. If you really suspect lift pump problems disconnect the secondary filter entirely and push the lift pump lever. It should spit some fuel at you so have a bilge absorber or paper towel at the ready.

Good luck! My yanmar was an infinitely faithful little rattle-banger dispite my abuse masquerading as maintenance.

MedSailor

brak · #3 04-27-2008

It takes a long time to prime your Yanmar with that tiny pump. On mine i do about 5-10 minutes of pumping. Usually, even after that quite a bit of air bubbles out of the bleed valve. My engine (and presumably Yanmars in general) are somewhat tolerant of that - they will suck the air and the fuel, smoke for a little bit and then work just fine. So, it may be ok not to get a perfect prime (though probably not ideal).

Rockter · #4 04-28-2008

It is an idea to use an electrical lift pump to pressurise the fuel system. Bleeding is then very rapid.

DrB · #5 04-28-2008

I plan to go back up Tuesday night to touch-up the bottom before we launch on Thursday night. I will run the motor for 30 more minutes to make sure that the air is really out. That should burn about a pint of fuel, which is more than the volume in all of the fuel lines.

The last thing I need is for the engine to cut out on me after they splash me. I have to motor upstream about a 1/4 mile on a river that has a current about 3 knots to our temp. dock. Downstream from the launch site is a bascule bridge that can only be passed in narrow channel when the bridge is up. Not a good time for the engine to go south.

Thanks also to everyone about the time it takes to bleed. I thought pumping 100 or so times would be enough, but I guess not.

DrB

NOLAsailing · #6 04-28-2008

Quote:

About your success, I would advise you to be cautious when you splash. I have never seen or heard of someone changing both fuel filters without getting air into the system first. I've been told it can be done, but I don't believe it.

Actually, if there's air in the fuel system, then it probably won't start at all. The wonderful thing about diesels is if it runs at all, it's probably all right. If you ran it for four minutes with no problem, then you're good to go.

The mechanical lift pump can be a pain. Some people have installed ball pumps (like you find on the tanks for outboards) to use in lieu of the lift pump. I've found that the lift pump is functional, but you absolutely have to be sure you get the full downstroke. On my Yanmar 2QM15, which is similar to yours, the first 85% of the stroke is easy, but ineffective. The last 15% has a bit more resistance, but it does pump the fuel.

One thing you may want to consider, in the event that you do need to bleed the motor while out, is to mark the various bleed points with a dab of yellow paint. As I'm sure you've discovered, if you miss one, you'll won't be able to start the motor.

You have to love a freshly painted motor. It's an engine rebuild kit in a can.

ScuzzMonkey · #7 04-28-2008

Quote:

Originally Posted by NOLAsailing

Actually, if there's air in the fuel system, then it probably won't start at all. The wonderful thing about diesels is if it runs at all, it's probably all right. If you ran it for four minutes with no problem, then you're good to go.

This is just not true; particularly if it is introduced via a filter change, it can take a while for air in the fuel line to kill the engine. After a primary filter change, I don't find out if I've bled the lines adequately for ten minutes or more--I've had the motor conk out after that long and need to be re-bled a number of times. Waiting four minutes is entirely inadequate if you want to make sure your lines are clean. You may well find yourself drifting five minutes after you launch.

I think your 30 minutes of idling to confirm that you are clean is closer to the mark. I give it 15 myself (I have a 2QM20) but 30 is probably safer.

arf145 · #8 04-28-2008

I second MedSailor's advice on pushing the lift pump lever far enough. If it is pulling fuel you should feel a little resistance in the travel of the lever--a squishy pump sort of feeling of liquid being moved. I've made two mistakes with that little finger torture device: one was not pushing far enough, and two was working it for 10 or 15 minutes with no effect when there was no fuel in the line to even pull. I primed it by cranking the engine a few turns, with the kill switch pulled and the water feed closed. Then some lift pump work until clear fuel ran out the top of the filter.

Tom

DrB · #9 04-29-2008

So I went back up tonight to make sure the engine was well bled of air. Started her right up and let her idle for about 5 minutes, then upped the engine RPM over the next 30 minutes or so. Throttled between 800 RPM and 3200 rpm every few minutes after the motor had warmed up.

No coughing, sputtering, or hestiation during the run. Exhaust had a a nice flow of water with occasional white whisp of smoke/steam.

My confidence level of no air and a no motor issues after splash is now way up.

Thanks for all the good advice. Will remember for the next time I have to bleed system.

DrB