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Frogwatch 11-04-2012 01:19 PM

easier diesel bleeding
 
Why does bleeding a diesel fuel system have to be such a PITA? Actually, it isnt if one really knows their engine but most people seem to have a problem with it.

On a Yanmar, you have to bleed at the primary filter, at the high pressure pump and at each injector. Each involves cracking a nut open while operating the tiny hand pump (I have an electrical pump that makes it much easier). Often, getting to these nuts and especially the injector Banjo fitting nuts is a real problem. Why not have simple Press to bleed type fittings? That way you would run the electric pump and simply use a stick to press down on the fitting to bleed instead of trying to get your wrench into tight places.

For that matter, the electric pump should be wired so that as long as the mech pump is providing pressure, it does not need to run.

captbillc 11-04-2012 02:31 PM

Re: easier diesel bleeding
 
i don't think a push to bleed on the lines from the injection pump to the injectors would work. these line have several thousand pounds pressure in them when the pump is delivering fuel to the injectors. usually you do not have to bleed the injector lines, just on the inlet side of the injection pump.

SchockT 11-04-2012 02:42 PM

Re: easier diesel bleeding
 
Funny, I have only ever had to bleed my injector lines once in 10 years, and that was my own fault for running out of fuel. Fortunately the banjo bolts are easy to reach on my engine. Also. I don't use the manual pump, I just crank the engine likeI always did on the big diesels when I worked as a HD mechanic. Is there some reason you can't do that on Yanmars?

jrd22 11-04-2012 03:20 PM

Re: easier diesel bleeding
 
That's how I do it Schock. As long as you don't open the raw water seacock while you are cranking (so you don't flood the cylinders with water) it works better than that little hand pump.

Frogwatch 11-04-2012 03:40 PM

Re: easier diesel bleeding
 
You guys may be right as I rarely bleed the injector lines and only bleeding the filter and injection pump seems to work.

eherlihy 11-04-2012 08:26 PM

Re: easier diesel bleeding
 
My Universal M25 uses an electric lift pump, and there is a valve which allows fuel to run through the complete system, yet skip the nozzle of the injectors. The engine is the equivalent of a Kubota D850. The exact procedure for bleeding the system is shown here; <iframe width="480" height="360" src="http://www.youtube.com/embed/XJn2kDnWQPU?rel=0" frameborder="0" allowfullscreen></iframe>

All that I have ever had to do to bleed the system is open the valve which is described at 2:50 in the video, and turn the key to "ON." Turning the key to ON, starts the fuel pump. After about 20 seconds, I close the valve, and the system is bled. :)

Stu Jackson 11-04-2012 08:45 PM

Re: easier diesel bleeding
 
Quote:

Originally Posted by eherlihy (Post 942954)
My Universal M25 uses an electric lift pump, and there is a valve which allows fuel to run through the complete system, yet skip the nozzle of the injectors. The engine is the equivalent of a Kubota D850. The exact procedure for bleeding the system is shown here; <iframe width="480" height="360" src="http://www.youtube.com/embed/XJn2kDnWQPU?rel=0" frameborder="0" allowfullscreen></iframe>

All that I have ever had to do to bleed the system is open the valve which is described at 2:50 in the video, and turn the key to "ON." Turning the key to ON, starts the fuel pump. After about 20 seconds, I close the valve, and the system is bled. :)

I'm sooooo glad I have an M25, too. :):):)

Easy to bleed. And to think I wasted two years before I got up the nerve to change the primary when we first bought our boat in 1998! :eek:

It's so nice to not have to mess with the injectors. At all!!!:laugher

Stu Jackson 11-04-2012 08:47 PM

Re: easier diesel bleeding
 
Quote:

Originally Posted by eherlihy (Post 942954)
My Universal M25 uses an electric lift pump, and there is a valve which allows fuel to run through the complete system, yet skip the nozzle of the injectors. The engine is the equivalent of a Kubota D850. The exact procedure for bleeding the system is shown here; <iframe width="480" height="360" src="http://www.youtube.com/embed/XJn2kDnWQPU?rel=0" frameborder="0" allowfullscreen></iframe>

All that I have ever had to do to bleed the system is open the valve which is described at 2:50 in the video, and turn the key to "ON." Turning the key to ON, starts the fuel pump. After about 20 seconds, I close the valve, and the system is bled. :)

I'm sooooo glad I have an M25, too. :):):)

Easy to bleed. And to think I wasted two years before I got up the nerve to change the primary when we first bought our boat in 1998! :eek:

It's so nice to not have to mess with the injectors. At all!!!:laugher

I've seen that video elsewhere on the internet, and going first to the injectors is not always necessary.

hellosailor 11-04-2012 08:48 PM

Re: easier diesel bleeding
 
"Why does bleeding a diesel fuel system have to be such a PITA?"
Some engines are actually self-bleeding. Others are a RFPITA requiring replacement of the crush washers every time.
The biggest problem is that you have to find out how to bleed each engine, then make sure you restrict your boat-buying to just those boats with self-bleeding engine installations. The PITA part of it? Is the unavoidable moron-tax levied by mass marketers on everyone, moron or not, because the mass market doesn't know or care about these things so the builders can knock some bucks off the MSRP and gain some market share selling cheaper inferior systems.

What else is new?

lostatsi 11-05-2012 10:17 PM

Re: easier diesel bleeding
 
I hope I don't get too much flack for this but here go's.
I have been around diesel's for at least 20 years. Take what you will from this information, all based on real experience.
Think of the system this way.
Fuel tank
fuel line to lift pump or low pressure pump or supply pump call it what you like. anywhere around 4 psi sounds close.
one or more filters are on the low side.
Return line, remember this one it's the secret to a long happy life.
#1 I can't remember "cracking" an injector line on the high side (about 1200 lbs) ever for any reason even after installing a new pump.
#2 Every boat should have an electric pump on the low side, if you don't then get one , you'll learn to love it. You can buy them at any auto-parts store for around $20. electric gas pumps work fine in my experience. Shoot for something in the 4 to7psi range ( carborated cars used them back in the day) .
Install it in the fuel line before any filters or factory lift-pumps. I have always run mine with a switch and leave it off (they free flow) unless I'm bleeding the system. The low pressure lines on a diesel MUST be free of any possible leaks, this cannot be stressed enough.
Almost all fueling problems can be traced to air intrusion on the low side.
If you run out of fuel simply run your electric pump for a few minuets before cranking. The fuel will be pushed through the low side system and back to the tank.
Set throttle at about 1/4 to 1/2. With pump still running, crank motor while spraying WD40 into air intake.
WD40 will not hurt your motor but will run up rpms as it gets in. You can use starter fluid but you better REALLY know what your doing or you might kick a rod! or two! LOL.
It is a two man system unless your able to jump the starter solenoid as I do.
Keep in mind that you need to NOT release the starter too soon. Let it overrun the starter just a little.
It'll run a little funky at first (thats why it needs some throttle) but will straighten right out.
BTW. You should only have to do this when you run out of fuel. When changing filters you can avoid this by filling the new filters with fuel or trany fluid. And even though it can be a drag to work on, try to change filters on a motor that is warm. Much easier to start a warm diesel. And when starting after a filter change, keep the rpms up till she straightens out.
I hope this helps a little. If you can start a lawn mower you can learn to start a dry diesel.


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