Bleeding air out of Diesel Engine??

**DougW** · 04-30-2007, 11:51 AM

Changed the fuel filter and now won't start. It seems that I have to bleed air for fuel system. Filled filter with diesel but that didn't quite do it. From the searches I've done it seems that I have to loosen a fuel line from pump to atleast one cylinder , crank engine. Not sure at that point if tighten back up when starts firing. Seems like a tricky move tightening up tubing leaking fuel on top of an operating engine.

Anyone done this??

Thanks

L7 · 04-30-2007, 11:56 AM

The engine won't be operating really. Just turn it over until you have solid fuel coming out of the line and stop. It won't fire and you may have to do each cylinder. Re hook line and fire it up. It just isn't tolerant of any air at all.

BLOOD SWEAT STEEL · 04-30-2007, 11:56 AM

I take it there's no bleeder screw on the top of the filter housing?

**Idris** · 04-30-2007, 12:05 PM

Isn't there a manual bleed/pressure pump either on the fuel filter assembly or just before/after it. Every diesel I've worked on had one of these (bar a ford transit (euro version of econoline) which had an auto bleed). just work the pump till its hard to pump. Crank the motor and it should run. Never had to bleed the fuel line manually?

**Arty50** · 04-30-2007, 12:11 PM

Originally Posted by Idris

Isn't there a manual bleed/pressure pump either on the fuel filter assembly or just before/after it. Every diesel I've worked on had one of these (bar a ford transit (euro version of econoline) which had an auto bleed). just work the pump till its hard to pump. Crank the motor and it should run. Never had to bleed the fuel line manually?

^ Yup. I used to help out the mechanics at my father's construction company and I can't remember seeing a diesel engine that didn't have a primer pump.

**DougW** · 04-30-2007, 01:15 PM

I'll look again at the manual to see if I can see it, but I don't seeing any thing labeled that way in the diagram.

**mntlion** · 04-30-2007, 05:38 PM

doug: what diesel do you have?

are you another RHD toyota guy too? (hilux for me in banff)

**addict** · 04-30-2007, 06:03 PM

What you might have to do is bleed the injectors if you got air in there. It's not that hard, but is almost impossible to describe on an internet forum verbally. But basically you'll need to find that primer pump that everyone's talking about, then either loosen off the injectors 1 by 1, or if it's well designed it'll have a bleed point. Pump the primer until it's pure flow on each. You may need to repeat. If it's a Nissan 6 cylinder which I doubt it is, I can scan my manual.

**jerr** · 04-30-2007, 07:00 PM

All diesels are designed differently. Some are designed with bleeding in mind but a lot aren't. Car/suv should have bleeder/primer pump, trucks may have, and larger plant sized diesels probably won't. I hope it's a car.

This might not be the best way for your model but I've always found a good fail safe way is to crack the fuel line that feeds the cylinder furthest away from the fuel pump.Then hand pump the primer or turn the motor over (activating the electric fuel pump) until the bubbly fuel becomes a solid stream. The motor should catch about then. As this happens tighten the fuel line back up and you're done. And diesel isn't as dangerous as petrol. It will (should) evaporate off a running engine rather than catch fire and it won't explode. We used to put cigarettes out in diesel as a 'party trick' when I worked in the mines. It goes against everything you think you know but diesels not so volatile. Having said that don't try it on my recommendation.

Good luck.

**DougW** · 05-01-2007, 07:58 AM

Its a Yanmar 4 cyl turbo, 110hp in a skid steer. A prime pump doesn't show up on engine diagrams so will have to go the manual loosen fitting route.

**Arty50** · 05-01-2007, 09:58 AM

Try calling a dealer for your skid steer. There might be a primer pump even though it's not in the diagram.

**DougW** · 05-21-2007, 07:15 PM

There was a prime pump. But it didn't work. Did call gehl and they said to use prime pump and if can't find bleed valve loosen fuel filter and bleed there. Also if tank was full to top should work without priming.

Well that was not the problem. It seems that the previous owner , a construction company, had done some mods. The fuel pump/ prime pump assy on the side of the injection pump was hosed back to itself. What they installed was an electric fuel pump. It was mounted quite high as that was they only place to mount it.

Solution: take pump off mounting bracket locate low so had flooded suction. Give pump 12v while hanging off hoses. remount pump and she started.

Before I did that made sure that pump worked and was actuallly getting 12v when turned key.

Now still is problem that will have to unmount then remount pump everytime work on fuel system. But for now back in business digging holes and knocking over stumps.

L7 · 05-21-2007, 10:56 PM

Back in business. Hope every stumble doesn't take as much research and hunting to find the hidden mod causing the problem.

**DougW** · 05-22-2007, 08:15 AM

they must have done it for a reason. Just didn't think out the resulting problem. I have no idea how they would have primed it other than doing what I did.

Same thing with the starter last year. They had changed some wiring but didn't solve the problem. Now its working great but took replacing the starter and getting the new one rebuilt twice, minor work on soleniod both times. Ended up rewiring circuit to starter soleniod. The diesel guys in Golden were no help so had to figure it out myself.