Yanmar 3YM20 bleeding advice?

[Lucky Duck]

Last night I drained some crud/water out of the water separator, last time I did this the engine ran without needing any bleeding.

I am concerned that was luck more than anything else. Are there any downsides of trying this again?

The manual mentions a bleed screw at the top of the fuel filter but nothing about the injectors so I wonder if this is an oversight or if they look after themselves

Any advice greatly appreciated

 

[Debenair]

Was this the fine filter on the engine or the pre filter?
If the former when I did my 3YM 30 recently I just opened the bleed screw and used the hand lift pump until clear fuel flowed.
The engine stalled the first couple of times I turned it over but then started and ran ok.

 

[coopec]

I'm most certainly no Diesel Fitter but why would you need to bleed the injectors if all you are doing is emptying out water from the filter. How would that let air into the high-pressure side of the fuel system?

If any of the experts out there think my logic is flawed could you please let me know?

 

[Lucky Duck]

Was this the fine filter on the engine or the pre filter?
If the former when I did my 3YM 30 recently I just opened the bleed screw and used the hand lift pump until clear fuel flowed.
The engine stalled the first couple of times I turned it over but then started and ran ok.

Pre-filter with a glass bowl and a drain at the bottom

Just spotted this similar thread there http://www.ybw.com/forums/showthread.php?454307-A-bit-confused-about-diesel-filters

 

[coopec]

Little Glebe

Every time I use that link it comes up as "The resource was not found"

I wonder if it is just my computer?

 

[Lucky Duck]

Just checked and its working for me - the thread is called A bit confused about diesel filters, posted by scrarambledegg its midway down the first page when I last looked

 

[blxm]

The 3YM20 has an automatic air bleed device, apparently. I bleed the system after changing the primary, engine, filter but not after clearing the water separator. However, it seems to be OK if you dont bleed an empty fuel filter . I discovered this when I forgot to bleed it after a change and it started after a couple of coughs and ran fine, not something I will try again. I would normally bleed using the bleed screw and lift pump. very quick job.

 

[Lucky Duck]

Thanks, I'll make sure the engine runs for a while before casting off!

 

[RichardS]

My 3YMs seem to run fine even if the Racors are half full of air when I start the engines - they don't miss a beat. Perhaps the air is automatically directed down the return and back to the tank?

Richard

 

[alan17]

That is a sensible plan. But also run it in gear under load whilst still secured.

Thanks, I'll make sure the engine runs for a while before casting off!

 

[blxm]

That is a sensible plan. But also run it in gear under load whilst still secured.

Good idea. It can run for a considerable time even with the fuel tap turned off, as I discovered. :redface-new:

 

[Lucky Duck]

My 3YMs seem to run fine even if the Racors are half full of air when I start the engines - they don't miss a beat. Perhaps the air is automatically directed down the return and back to the tank?

Richard

Ta, I had a look online at the manual for the GM series which had the procedures for bleeding the high pressure side so hopefully that all happens by magic on the YM series

 

[Lucky Duck]

Good idea. It can run for a considerable time even with the fuel tap turned off, as I discovered. :redface-new:

A variation on that theme is to leave the stop cock for return pipe closed

 

[RichardS]

A variation on that theme is to leave the stop cock for return pipe closed

I have return ball valves on my engines. What actually happens if the return is closed and the engine is started?

Richard

 

[Lucky Duck]

The engine ran but the revs kept surging until we found out what the problem was after couple of minutes.

 

[RichardS]

The engine ran but the revs kept surging until we found out what the problem was after couple of minutes.

Interesting. I have never closed my return valves but it's useful to know what the symptoms might be.

Thanks

Richard

 

[Lucky Duck]

The only reason it was closed was the engine was removed for an overhaul and had only just been lifted back in

 

[Lucky Duck]

Good news is that engine started fine and has run for a reasonable amount of time at just over 2k revs so it's looks like that potential panic is over

 

[blxm]

Good news is that engine started fine and has run for a reasonable amount of time at just over 2k revs so it's looks like that potential panic is over

Excellent news