Priming/Bleeding air from a 1hz (1 Viewer)

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I break things.
Aug 14, 2006
Oceanside, CA
When searching, someone suggested pulling the glow plugs (at least three) and cranking until you see diesel at the gp holes to prime a 1hz.

We are trying to start the engine with batteries on the and jumpers to test it before we finish the build. I'm a little covered about having diesel shoot out of the gp homes with the batteries that close (sparks from the wiring).

Is there another way, or am I being overly cautious?

FYI. I have a Racor fuel filter that I have primed, but it is back by the tank (going to install an OEM pump in the engine compartment soon for double protection) so I am not sure the lines are fully bled.

Any suggestions are appreciated!
Diesel won't ignite from a spark. You may get a mess but not a fire.

How did you prime the Racor filter? Have you verified you're getting fuel at the injection pump?

I'd pull all size of the plugs out and crank the engine until you see fuel. You could disconnect the injection lines at the injectors and watch for fuel there. (This would be better than having it go in the cylinders and no burned.) After you get it started you'll likely need to individually bleed air from each injector anyway.
It was probably me who mentioned removing 3 plugs, I got it from the FSM. You should try igniting diesel with a bare flame, its near impossible without sustained heat.
The amount of fuel that comes from each glow plug hole is miniscule and is atomized to a spray that is extremely small.
As Rufus says, make it even easier and remove all the plugs. The engine will spin around as fast as a slow idle.
But disconnecting the injector lines means you will still have air in the injectors.
As I said before ,the amount of fuel in each charge is miniscule and will not stay in the cyl as the piston forces it out. The whole idea is to see the plumes exiting the engine and know you have atomized fuel coming out of the injectors.
I removed all the plugs on a newly rebuilt engine and had fuel coming out the holes in 20 seconds. replaced them and it fired in 2 seconds and ran as smooth as a diesel can.
NO mess to clean up what so ever.

If this doesn't work ,you have other problems.

If you have sparks from loose connections , I would tackle that as a matter of good practice and to ensure you are getting a full charge of electricity to the starter.
I did it with an old and not so large battery from my 3F engine.
To be clear, the safest thing to do would be to remove the Glow Plugs, crack each injector line, and crank it with the starter. That said, Rosco is right about the difficulty igniting diesel. Unless you have the injector itself squirting onto a sparking connection, it's just not much of a concern.

You have two goals here:
  1. Spin the engine quickly to oil it up nicely
  2. Make sure you're getting fuel to the injectors
No matter what you'll need to bleed each injector once you get it to kick over, just to smooth it out anyway.

No matter what you'll need to bleed each injector once you get it to kick over, just to smooth it out anyway.


But why would you need to bleed them if you have 6 perfect plumes of diesel spray exiting the glow plug holes?
Once you stop cranking the engine, the diesel is held in the injector. It will not flow back unless it is leaking air, which shouldn't be happening if you are this far into it anyway.
In any case ,once the engine starts , it will self bleed and run smooth in under 30 seconds. I only get that when a small amount of air gets in after a fuel filter change.
After 9 years of driving vehicles with 1HZ's , I can only remember bleeding the injectors once when I had the rebuilt engine. (I have had lots of experience bleeding industrial diesels from allowing them to run out of fuel)
Its a sealed system and the less often the lines are cracked ,the better.
You were all right! I primed the filter (Took forever) and then cranked. It ended up that there was a nick in the fuel line by the tank from some frame cleanup we had done and the line was sucking air. We fixed that and then primed the pump by pressurizing fuel into the feed and then cranking.

She started to catch and seemed to have good compression so we stopped it before she took off. We didn't want her to fully run until we had everything wired up. We also had closed off the injectors and the glows.

I will be finalizing the wiring tomorrow and will try to get her running fully tomorrow or Sunday. Should be fun!

Thanks for all of the advice! Once we fixed the air leak, it was a fairly easy thing to get combustion and so the bleed process should be painless from here.

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