Bleeding a Yanmar 3GM30F

[dunedin]

I did the diesel filters on Sunday - the usual messy but relatively simple task.
Usually bleeding to the screw on top of the second filter does the trick. But this time it ran for about 60 seconds and then died. The documentation I have suggests I need to bleed the high pressure side by loosening nuts at the injectors, whilst turning the engine over. But there is nothing more to explain.

Any hints
* which nuts exactly - couldnt budge the ones I thought it should be, and loosening the ones on top of the units didn't work
* is this possible as a one man job ? to turn over the engine on my boat need to be in the cockpit, but nuts are down below ?

Any hints from the experts ?

 

[Fr J Hackett]

It is best done by turning the engine over by the starter motor so 2 man for you, it is possible by using the decompression levers that you can turn over by hand using the starting handle. The first "nut" is at the high pressure pump with the metal pipes comming out of it you do each in turn and tighten the nut as soon as you see fuel. After this you should be able to start the engine. Are you sure that you are not sucking air in at the low pressure side the copper washers are highly susceptable to leaking and should either be replaced or annealed after disturbing. In bleeding the engine go back to square one and work through primary secondary filters injection pump in turn making sure you have fiel at each point before moving on.

Good Luck.

 

[PaulR]

did mine at weekend too- we bleed it on main bleed nut on top of replaceable filter housing and then second bleed nut where high pressure pipe from that housing goes into the pump? on engine out of which the 3 pipes to the injectors come - bleed screw (open with spanner) is to left side when viewed from front of engine - crack that open - carry on pumping the pump by hand then when fuel comes out close it and in our case engine then started and ran happily - good luck

 

[affinite]

On my 3GM30 I did need to bleed the final high pressure lines into the injectors so I dont think you should stop at the LP side of the HP pump. I cant shift my engine by hand even with decompression lever on so it is a 2 man/person job. When bleeding dont forget to put throttle on full (out of gear) and try to tighten nuts back up before stopping engine or some air may bleed back in.

 

[salamicollie]

Procedure for a 3GM or 2GM for that matter is bleed thefirst fuel filter then fuel filter on the engine by opening the bleed screw (bolt with cross head - but use a spanner) by using the lever on the fuel pump. once this running clear close and open bleed screw on injector pump, keep pumping using the lever until again no air in fuel and close.

You may need to turn the engine over slightly to get the hand lever to pump freely.

Try to start - it most cases thats enough as the yanmar injectors are supposed to self bleed. Remember that if it is cold you will need lots of throttle to get a GM series to start!

If the engine wont start (lots of throttle in neutral) then you will need to bleed the injectors. The bleed screw is again the nut with the cross head on top of each the injectors. Turn the engine over with the injectors open and as suggested above keep the engine going while you close the bleed screws.

If that doesn't work its possibly a problem with the injectors possibly - injectors can be checked by your local lucas centre