MD Water trap won't purge all of the air

sflem849 · Jun 10, 2010

I ran the tractor w/o turning the fuel on the other day and it let air in the fuel bowl. Now when I try to get the air out it gets fuel within an inch of the top and can't get any more air out. The screw is letting out pure fuel and the first filter if flowing clean. (fuel level in tank is near full)
When I rebuilt the lift pump about 5 years ago it did this same thing to me. I could never get all the air out until I rebuilt the injectors this spring. When I bled the system that time I got it all out?!?
On the side, there was an MD w/ the Bosch pump at the pull this weekend and it had the same problem. The guy running it just shrugged when I pointed it out and said it is always like that...it runs fine why would I mess with it!?!
What's going on?

BOBM25 · Jun 10, 2010

Mine is the same. That glass bowl is never completely full. I have the IH pump. Mine also runs good so I never messed with it.

pete 23 · Jun 10, 2010

I think you can get it full if you loosen the bowl but then of course it may leak if it hasn't been off for a while as they warp out of shape pretty easy. Sometimes, bleeding a bunch of fuel farther down stream from bowl will also get it out. I had a 450 on the dyno once upon a time and you could not get rid of the air pocket, but it was actually drawing in a little bit of air through the bowl drain tube, because the baffle in fuel tank was laying on the outlet in tank blocking flow do primary pump was sucking it's poor little heart out trying to get enough fuel. Of course the air bubbles had all concerned that I had a leak some place, me being new to diesels at the time had to literally get the boss out of my hair and figure this thing out myself as he was calling the diesel shop and all that good stuff. But it worked out in the end. Cut a slot across the stand pipe on fitting and just lelf the baffle bounce around. Not saying this is your problem just relating some experiences I have had over 50 years ago.

sflem849 · Jun 10, 2010

(quoted from post at 09:52:02 06/10/10) I think you can get it full if you loosen the bowl but then of course it may leak if it hasn't been off for a while as they warp out of shape pretty easy. Sometimes, bleeding a bunch of fuel farther down stream from bowl will also get it out. I had a 450 on the dyno once upon a time and you could not get rid of the air pocket, but it was actually drawing in a little bit of air through the bowl drain tube, because the baffle in fuel tank was laying on the outlet in tank blocking flow do primary pump was sucking it's poor little heart out trying to get enough fuel. Of course the air bubbles had all concerned that I had a leak some place, me being new to diesels at the time had to literally get the boss out of my hair and figure this thing out myself as he was calling the diesel shop and all that good stuff. But it worked out in the end. Cut a slot across the stand pipe on fitting and just lelf the baffle bounce around. Not saying this is your problem just relating some experiences I have had over 50 years ago.

It's good to know everything that can happen!

I replaced the bowl five years ago and it hasn't been off since. I suppose that is not very long in the entire life of the tractor. Maybe I wil take my chances and pop it off. Would you just leave the tank valve on and then let the fuel fill it up until it ran over the sides?

Andrew Z · Jun 10, 2010

Mine does the exact same thing. However when there
is over say 12 gallons in the tank it seems to fill
the bowl more then when there is only 2 or 3
gallons...

Andrew

caterpillar guy · Jun 10, 2010

It has been a while since I looked at it. It has what looks like the release for a hydraulic jack on the top of the metal plate the glass bowl clamps to the bottom of. Ours has always ran full.

pete 23 · Jun 10, 2010

Just loosen it with the fuel turned on.

sflem849 · Jun 10, 2010

(quoted from post at 19:06:03 06/10/10) Just loosen it with the fuel turned on.

That's what I did and it worked great. It doesn't even appear to be leaking!!! I then used "the bottle jack" screw to get the last little bit out and I am good to go.

MD Water trap won't purge all of the air

sflem849

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BOBM25

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pete 23

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sflem849

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Andrew Z

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caterpillar guy

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pete 23

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sflem849

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