Oil & Fuel Air Bleed Advice

[Rebol]

Hello All,

I'm quite new to my my old tractor. I believe it to be a 70's era MF-40. I have to air bleed the critter (it's a long story) and I have some questions. I have a manual so it's not so much the general process but some specifics. Any help is most appreciated.

1. I am assuming the air vent plug is located on the fuel filter's "cap" top side. Mine is across from the fuel line and it looks like if you could reverse the cap then the fuel line would screw into it. So it's directly opposite that line. The only other bolt is on top and that holds the filter. Hopefully that's the one. The manual just assumes one knows where that is. Is that the correct bolt?

so far so good?

2. The pump is "conveniently" located on the other side so I can't see what goes on but when I pump it, I do get bubbles and then it slows down to some drips. The fuel never "gushes" out. Is it suppose to?

3. When you pump is it possible to actually introduce air? I noticed that if I go back and pump some more, more bubbles come out, then the drip. Should I keep repeating that until it eventually has no bubbles? Really it's this part I am stumped at. Also the very act of pumping might be an art. Do you all just pump very slowly?

4. After this I will move on to the lower and upper vent plugs on the injection pump. Thankfully there was a picture there.

5. The manual says to loosen "a" pressure line at the injection connection. There is one such connection that I can see and get to physically. I'm hoping I don't have to loosen any more before I crank it. Any thought?

Thanks in advance. I'd love to say I rescued my MF from its sorry state.

Rebol.

 

[dex3361]

Welcome to TBN. You are on the right track. After you bleed it at the injector, try it to see if it will fire off. If it will not then crack the fitting at the injector 1/4 turn and crank it over about five or 6 seconds tighten the injector connections and then try it again. I usually did not have that difficult of a time in the bleed process on the Massey.

 

[Rebol]

Thank you for the quick reply. I will try that.



And by the way, "Every one that is of the truth heareth my voice." I hear you brother.

 

[Zork]

Do you have to air bleed it every time? You shouldn't have to bleed it unless you run out of fuel or you have an air leak that is causing the fuel to siphon back to the tank. Edit: Any previously damp connection should be suspect for air problems.

 

[tcartwri]

I just crack the fitting on the return line going into the injection pump, turn the motor over until it fires, wait until there are no more air bubbles flowing past the fitting, and then tighten it up. It's not gasoline, so it wont flash ignite on you. Have lots of rags handy though.

 

[Rebol]

Zork,

No, what happened was I took the kinds out for a ride and it had been raining a lot so when I hit a soft spot on a slight incline, the left tire sunk in bottomed out. I was also low on fuel at the same time (I bought this thing used and the gauge doesn't work). The angle she was left had her tilting to the side and I think that was enough to cause the problem when I tried to start her up again. Normally she fires up with no problems.

Anyway, it's really been a good way to learn about my tractor.

 

[Rebol]

tcartwri,

Thank you. I will try that too. I appreciate the help.

 

[Rebol]

OK,
Following some of your advice, I managed to get it running for a few seconds. I did the "crack the nut on the injector method" and noticed that while I eventually got it to stop bubbling, my suspicion is that there is still more air in the line.
Have any of you ever seen that before? I guess I just have to keep repeating the above method until it finally runs.

When you all have done this, is this what you experienced or did it work right away?

Thanks!

 

[qball98]

You may need to bleed each of the lines going to the injectors to. If you have all the air out to the pump there is still probably air between the pump and injectors. Its not hard just loosen the line at each injector one at a time while cranking it over. When that line starts spitting out fuel tighten the nut and move on to the next one.

 

[Zork]

If the cyl is firing (engine stumble with loose fuel line/picks up when line is tight) that air should be carried away through the bleed off lines on the top of the injector (if you have these). Once the system is relatively free of air it should eventually clear up via bleed hoses/lines. If you encounter the problem again; or additional major air you have a leak somewhere. All damp/cracked hoses and fittings should be suspect for air entrainment. Keep us posted.

 

[Rebol]

OK,

I wish I could say she's back in action but alas this is not the case. I've managed to get it running for about 20 seconds three separate times today. Each time it stops I check the lower vent plug and I see those now familiar bubbles. I'm beginning to think I do have a leak somewhere but there's no sign of that in terms of wet/dampness.

This is what I have been doing:

1. Crack the bolt on the fuel filter and let it bubble till only fuel comes out. On the last couple of times it appeared there were no bubbles which also leads to believe the problem may lie somewhere between there and the injector.
2. Crack the lower vent plug on the injector and bleed.
3. Crack the upper vent plug on the injector and bleed.
4. Crack the "accessible" pressure line on the injector and bleed.
These steps are from the manual, by the way.
5. Crank it till it starts (allowing for cooling down periods).
6. Repeated three times today then it got dark + the battery recharge

I do have these questions though:

* There is a knob where the fuel comes out at the bottom of the tank, I'm pretty sure that's the fuel shutoff valve and I have that loose but not all the way loosened. Is that relevant?

* Is it just possible there really is that much air in the lines that I do have to repeat this process over and over?

* What are your experiences with air bleeding? Have you had to go through so much or am I just lucky?

Thanks for the help. One day...

 

[whistlepig]

OK,

I wish I could say she's back in action but alas this is not the case. I've managed to get it running for about 20 seconds three separate times today. Each time it stops I check the lower vent plug and I see those now familiar bubbles. I'm beginning to think I do have a leak somewhere but there's no sign of that in terms of wet/dampness.

This is what I have been doing:

1. Crack the bolt on the fuel filter and let it bubble till only fuel comes out. On the last couple of times it appeared there were no bubbles which also leads to believe the problem may lie somewhere between there and the injector.
2. Crack the lower vent plug on the injector and bleed.
3. Crack the upper vent plug on the injector and bleed.
4. Crack the "accessible" pressure line on the injector and bleed.
These steps are from the manual, by the way.
5. Crank it till it starts (allowing for cooling down periods).
6. Repeated three times today then it got dark + the battery recharge

I do have these questions though:

* There is a knob where the fuel comes out at the bottom of the tank, I'm pretty sure that's the fuel shutoff valve and I have that loose but not all the way loosened. Is that relevant?

* Is it just possible there really is that much air in the lines that I do have to repeat this process over and over?

* What are your experiences with air bleeding? Have you had to go through so much or am I just lucky?

Thanks for the help. One day...

Once the diesel starts after bleeding it should keep running. It may sputter a bit until all the air is out but once it fires up it should stay running. Repeated bleeding isn't going to help. It could be sucking air into the fuel but it would also be leaking fuel through the same place. Could be that the fuel hole at the bottom of the tank is plugged. You don't have to get every single molecule of air out when bleeding. Just enough to start it. I would give the motor a good cleaning and drying out and then watch for traces of diesel leaking.

 

[Rebol]

Thanks. That's good advice and to the point. I'm now more than sure there is a leak somewhere. I'll start a new thread since I've become somewhat of an expert at air bleeding

 

[whistlepig]

Leaks on the feed from your tank to the injector pump shouldn't be a problem. Leaks from the injector pump to the injectors on the motor (after the fuel is pressurized) are the leaks to be concerned about.

 

[JJ. in B.C.]

I would suspect a hole in the diaphram of the fuel lift pump

 

[banjodunn]

G'day i think you need to pull the fuel tap out of the tank and check the gauze filter that pokes up into the tank also on your lift/ prime pump you should have a removable top that will have/ should have a gauze screen in it check both these for blockage while you are at it give the fuel lines a good blow out esp if it has got banjo fittings anywhere as these sometimes contain
small filters

Jon