MF-135: bleeding the fuel system

   #1  

flusher

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I'm getting ready to change all the fluids in the 1966 MF-135 diesel that I'm fixing up.

Changing the fuel filters requires bleeding the air from the fuel lines.
That's an easy job on my 2005 Kubota B7510HST--just crank the starter.

Question: is bleeding the lines a slam dunk or a big headache on the MF-135?
Any advice and/or horror stories?
 
   #2  

JJ. in B.C.

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You shouldn't have any problem at all if you follow the correct sequence, do you have the operators manual ??
 
  
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flusher

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JJ. in B.C. said:
You shouldn't have any problem at all if you follow the correct sequence, do you have the operators manual ??

Yep, got the ops, service and parts manuals.

The fuel filters and the high pressure fuel pump (the injection pump) are on the left side of the engine while the low pressure fuel pump (the primary pump) is on the right side. You have to loosen air-vent plugs on the filters and on the injection pump one at a time while operating the primary fuel pump with the manual lever on that pump.

Question: do you have to close the air-vent plugs while operating the manual lever to make fuel squirt out of the vents? If so, that makes the procedure a two-person job (or single-person job if you have arms like an orangutan). Or can you lever the pump until fuel squirts and then walk around to the left side of the tractor and close the air-vent plugs?

Just trying to gauge what kind of problems I might run into if I do this job by myself.
 
   #4  

Farmwithjunk

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flusher said:
Yep, got the ops, service and parts manuals.

The fuel filters and the high pressure fuel pump (the injection pump) are on the left side of the engine while the low pressure fuel pump (the primary pump) is on the right side. You have to loosen air-vent plugs on the filters and on the injection pump one at a time while operating the primary fuel pump with the manual lever on that pump.

Question: do you have to close the air-vent plugs while operating the manual lever to make fuel squirt out of the vents? If so, that makes the procedure a two-person job (or single-person job if you have arms like an orangutan). Or can you lever the pump until fuel squirts and then walk around to the left side of the tractor and close the air-vent plugs?

Just trying to gauge what kind of problems I might run into if I do this job by myself.

I've gone through that filter change/bleeding air scenario about 30 times over the years on my 150. It's relatively easy, but there can be times where it doesn't go quite "by the book".

Step 1. Shut off fuel petcock on bottom of fuel tank.
Step 2. Drain filters.
Step 3. Install new filters, leaving SLIGHTLY loose.
Step 4. Open fuel petcock. As fuel begins to leak around filter, tighten completely. (May need "persuasion" with lift pump to get fuel flow to filters)
Step 5. Open bleed screw on filter and bleed all the air bubbles using lift pump to force fuel to filters. When satisfied filters are bled, close bleed screw.
Step 6. Open (I REMOVE) LOWER CHAMBER bleed screw on injector pump. Work lift pump until good flow of fuel is running from that bleed point. Close and tighten that screw.
Step 7. Do same as step 6 with UPPER CHAMBER bleed screw.
Step 8. Crack open rear-most injector line fitting nearest to cylinder head.
start cranking over starter. Fuel should seep from that loosened fitting. At that point, you're close. Engine should fire. As soon as it does, tighten fitting.

At any point where proccess starts to "break down", go back and repeat. Any amount of air in the system will cause an "air lock" of sorts.

That's what always works for me. Your results may vary.
 
  
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Thanks for the details. Hope I can get the job done on the first bounce.
 
   #6  

7mmrum

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A few months ago I helped my father changed the fuel filter on his MF135 diesel, orchard model. I think it was out of commission for 2 weeks until we finally pull started it with another tractor to get it started.

We followed the book to a "T" checked other reference materials, started over, and over again with the steps to get the tractor started, it was a major pain in the butt. I don't know if I would do it again. I don't mean to shy you away from changing the fuel filter, becuase it is supposed to be changed, but on this specific tractor, whew it was a struggle to get it running again.
 
  
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Thanks for sharing your trevail.

That's the reason I started this thread.

Plumbing has always been a headache for me whether it's water plumbing in the house or fuel lines on a tractor. I always run into problems and the job takes forever to finish.
 
   #8  

ozzie tractor

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the 135's aren't so bad to bleed,
1/.change filters, and open bleeders on filters,
2/.turn fuel on and start priming (yes 2 people will be MUCH easier)
3/.keep pumping until a good stream of fuel comes out the bleeder. then pump for a bit more to make shure there is no air still coming through.
4/. tighten filter bleeders and open lower one on injector pump. more pumping.
5/ now do the same for the top bleeder on the pump.
6/. now crack all the injector lined half a turn. open the throttle fully.
7/. crank the engine over until all the injector lines have fuel spraying out from around the nut.
8/. tighten injector nuts and follow normal starting procedure, but still use some throttle until the engine starts and picks up revs, then shut the throttle back to about 1/2. if it still wont start, recheck all bleeders for air, then try tightening the injector nuts while the engine is being cranked.
you really need to use a bit of throttle to give the pump enough cpacity to push any remaining air through the injector. also have a set of jumper leads handy, because now is when you will find out how good the battery is. never crank the starter for more than about 10 seconds without letting it cool either.
happy huntinng
 
  
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flusher

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ozzie tractor: thanks for the helpful tips.
 

Farmwithjunk

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ozzie tractor said:
the 135's aren't so bad to bleed,
1/.change filters, and open bleeders on filters,
2/.turn fuel on and start priming (yes 2 people will be MUCH easier)
3/.keep pumping until a good stream of fuel comes out the bleeder. then pump for a bit more to make shure there is no air still coming through.
4/. tighten filter bleeders and open lower one on injector pump. more pumping.
5/ now do the same for the top bleeder on the pump.
6/. now crack all the injector lined half a turn. open the throttle fully.
7/. crank the engine over until all the injector lines have fuel spraying out from around the nut.
8/. tighten injector nuts and follow normal starting procedure, but still use some throttle until the engine starts and picks up revs, then shut the throttle back to about 1/2. if it still wont start, recheck all bleeders for air, then try tightening the injector nuts while the engine is being cranked.
you really need to use a bit of throttle to give the pump enough cpacity to push any remaining air through the injector. also have a set of jumper leads handy, because now is when you will find out how good the battery is. never crank the starter for more than about 10 seconds without letting it cool either.
happy huntinng

Reason why I suggested cracking open rearmost injector only? The rest are a BEAR to get at. I've always been able to bleed from one injector. BIG, old fingers don't get into tight spaces anymore.
 
 
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