easier diesel bleeding

[SchockT]

Lostatsi,

I was with you all the way to the WD40 thing! That to me is a bad idea just as starter fluid is! There should be no reason to used any volatile sprays to get an engine running except perhaps if the engine is old, worn out and has low compression!

[bristol299bob]

Lostatsi, I'm intrigued, are you saying you can bleed the system without opening any bleed screws? I've never heard of this.

If I understand the concept correctly:
- provide positive fuel pressure via an electric fuel pump
- Use WD 40 to start the engine
- the engine will draw air and fuel through the fuel lines, essentially bleeding itself through the injectors.

Is that correct?

[Maine Sail]

Originally Posted by hellosailor

"Why does bleeding a diesel fuel system have to be such a PITA?"
Some engines are actually self-bleeding.

Yep our Westy is self bleeding. I simply change filters and turn the key on. I then wait until the tone of the pump changes and she's good to go... Takes all of about 10 seconds....

[maccauley123]

Bleeding the fuel system on my Universal MB20 scared the crap out of me with fears of not getting all the air out of the system and having a motor that wouldn't run. A friend of mine gave me a tip which I did and it makes the whole thing much easier. He suggested I do what he did and install one of those fuel line squeeze bulbs in the feed line. Did it last spring and it works great and was tested on two occasions.

The first was the basic fuel filter change which I had never done. Removed the old filters and installed new ones after filling as much as I could with fuel. Opened the bleeder screw at each filter, hand pump until fuel comes out with no air and shut the screws. Did on primary and secondary and engine started up fine. With this arrangement I can be right over the engine and watch bleeder valves while I pump.

The other was an occasion while on the water. Was motor sailing out the channel and heeling pretty good. About 3/4 of the way out the engine sputters and dies. After a brief moment of panic I thought through things and realized what the problem was. I had let the fuel get below half a tank. We were on a starboard tack with a fuel pickup on the starboard side so with all the fuel pushed over to port the engine died. Got back to flat sailing and did the same process as changing the fuel filters and started right up.

[Maine Sail]

Keep in mind that no fuel bulb out there is approved for this type of use. Your M3-20B has an electric lift pump and you can easily jumper it off the solenoid with alligator clips while opening the bleed screw. Wear some nitrile gloves and have a diesel absorbing pad and bleeding these engines takes a few seconds.

1- Disconnect + feed to fuel pump insert alligator extension lead.

2- Clip extension lead to solenoid hot lug to make fuel pump kick on.

3- Crack bleed screw

4- When fuel flows close bleed screw

5- Run engine for sufficient time to ensure no entrapped air. If you still have air repeat above steps..


This is a fuel bulb I found cracked on a Trawler. The boat STILL SMELLS to this day.... Owner thought he had a leaking fuel tank.


If you must install a fuel priming bulb I would recommend a by-pass loop for it with positive shut offs on either side. But again your boat already has the tools you need to bleed the engine...

[Captainmeme]

I have been considering the installation of the fuel priming bulb on my Yanmar 2gm20.
Considering the above picture I won't be doing that.

[lostatsi]

SchockT
Yes WD40 is flammable, but compared to starting fluid it's edible,LOL!
A diesel has about 20 to 1 compression ( twice that of a gas motor) and no spark plugs. It makes fire by smashing something flammable till it explodes. WD fits the bill.
Keep in mind that unlike a gas motor a diesel has no air intake regulation. The only rpm regulation is achieved by fuel input.
When using any spray while cranking the motor the motor will sound horrible! You will regulate the rpm by adding more or less WD. The trick is to not release the starter too soon. Trust me the first time I show people this it is a little scary (for them)!
You've got your head next to what is all ready a noisy motor when running normally, Your spraying WD and thinking the thing is gonna blow.
Not for everyone, Not trying to sell you on it. Just real time experience.
Started many OTR trucks spraying 2 or3 cans at the same time! A little much for a 3 or 4 cyl. 1 can with the spray tube does the trick.
In reality you could skip the whole bleed process if you can live with the horrendous start up knock of WD40.
Bristol
I often find that people are put off by any dry restart process. The motor will knock and smoke and jump around. It's normal.
I still recommend a low side pump. Often they will make the WD40 unnecessary. Just remember to bring your throttle up and and let it crank a bit even while it sounds like it almost running.
Yanmars are in most tractor trailer refer units. Their prestart button simply runs the electric fuel pump.
If your up for a little diesel 101, with your motor running normally at idle give just a tiny little wisp of WD40 down the intake. You'll hear a little knock and a little rpm surge. It will give you an idea what to expect if someday it's your only option.

[Brent Swain]

My Isuzu diesel has a piston type fuel pump mounted on the side. When I ran her out of fuel one night, I simply added fuel to the day tank, pumped the pump until I heard fuel running back into the tank thru the return line. Then I fired her up, and she ran happily ever after, no bleeding required. All diesels should be rigged that way.

[SchockT]

I am familiar with how a diesel engine works! When I was a heavy duty mechanic's apprentice we used cans of ether to get big diesels running all the time, but those engines were far more robust than a small marine diesel! That horrendous knocking sound you describe could do horrendous damage to your engine. Because it is so much more volatile than diesel it will ignite before it gets to the top of the compression stroke. But hey, it's your engine! I'm just saying I would never do that to MY engine!

[maccauley123]

Maine Sail, what is it about a diesel installation that makes use of a fuel bulb a bad idea? One cracked bulb does not make a case that it is never a good idea, it could have been a faulty bulb and a faulty fuel line is just as possible. I understand my engine makes bleeding possible but the ease of simply squeezing the bulb to push fuel is a lot easier than messing with jumping lines. A squeeze bulb is designed to be used repeatedly with a gasoline engine and is generally outside. I will use mine one to two times a year and will be inside out of weather at all times so very protected. I have read some about this idea including below and am happy with the idea. Idea I saw a few times of replacing it every five years or so is a good idea.

From BoatDiesel.com.
"I have been using Squeeze Bulbs with diesel fuel for well over 20 years now. I still have not seen one rot or fail externally, so to me they have withstood the test of time in the field."
"Nothing I have used does a simpler or better job than the old fashioned and simple "Squeeze Bulb" as to priming the system or using it as a tool to check for other fuel system problems."
"I think the value of this type in installation is 100% obvious to most anybody that has gone through priming a diesel engine in a vessel from both the practical and safety standpoint when you have to get your engine running"