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posted to alt.auto.mercedes,rec.boats.cruising
Bill
 
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Default Bleeding a diesel engine

Gordon Wedman wrote:


"Gogarty" wrote in message
...
For the very first time in some 60 years of driving, I ran out of fuel
yesterday. Der Klunker ('81 300SD) suddenly started sputtering and
stumbled to a halt, luckily in a parking lot. Opened the hood. Sure
enough, no fuel in the sight glass. A couple of kind gentlemen helped me
push the car out of the way and in due course road service arrived with
two gallons of diesel fuel. They were concerned that it would be very
hard to get a diesel that has been sucking air to start without a lot of
work. If this had been my boat they would have been entirely correct. But
this car has a built-in priming pump on the engine. A few strokes on the
pump, the sight glkass filled up and a few more strokes later a hissing
sound confirmed that the byapass valve on the injectopr pump had openen
meaning the pump was now ready to send fuel with no air to the injectors.
She started with a couple of turns on the starter.

Now, why can't boat diesel engines be set up like that? I live in terror
of the boat engine sucking air becaise it will stop and bleeding the
system in a seaway or even at the dock is an exercize in contortion and I
don't pretzileize so well anymore.


Well you can make things a little easier on yourself:
- Racor has a fuel filter with a built-in hand pump
-or you could install an electric pump in the fuel system
-only open the bleed screw on the injector pump, at least as a first try.
My experience (with Yanmars) is that if you pump fuel to the injector pump
the engine will start, run rough, and then operate normally. No need to
bleed injectors.
-my other experience with Yanmars is that the hand lever on the engine
fuel pump is pretty useless for bleeding, hence my addition of the Racor
filter with pump.

I agree with you about the hand pump on the Yanmar engines. It's useless.
I spent half a day trying to bleed mine after cleaning the Racor filter and
finally gave up and called a mechanic. A $100 lesson I remember well. He
took it all apart and installed a squeeze hand pump on the line between the
tank and the Racor. Now I pop off the Racor, replace the filter, place the
top of the Racor back on and squeeze the pump until fuel leaks out the
Racor a little then tighten it up. I haven't had a problem since changing
filters. I don't believe I've had air in the line between the Racor and
injectors but opening the injectors and squeezing the hand pump would
probably fix that also without too much work.
--
Bill Boyher
s/v Summer Rose