Is anyone else being driven insane by mowers that don't cut ?

Well this is driving me absolutely insane. I've tried about 5 times now to bleed the air from this tractor. so we have:

1) cleaned fuel tank
2) new Orings added to the tanks/sump taps.
3) new diesel filter
4) exchanged lift pump (as I kept getting air at the injection pump bleeder ... and thought maybe the lift pump was introducing air)
5) endless deisel wasted all over the ground.


Ok, so I have the bleeder half way up the pump, usually always free of air, the bleed bolt at the top of the pump, there is no air there. The is always air at the pump return line if I crack it at the filter when trying to start it .... there seems to be endless air at the injectors if I leave them cracked.

I've managed it start it a few times, but it runs for about 10seconds and I've got air in the injector lines again. Where on earth is the air coming from ?? This is just nuts.

Maybe the new filter doesn't fit the housing well enough? but surely given the lift pump, this would create a leak of deisel to the outside world, not an air leak to the pump.

Can the pump itself be sucking air from the outside world .... somehow :confused:
 
the more I think about this, the more I'm sure it can only be the suction side of the lift pump that can introduce air. everywhere downstream of the pump will leak fluid, not suck air in. I don't htink this is possible or it would have an obvious diesel leak (via gravity) with the tractor sitting.

Would the new tap seals allow air in maybe ? (surely they would let fuel out as well as air in if that was the case). Maybe i still just have't managed to get all the air out (which is just insane given the bleeding everywhere has had).
 
Heres an idea .... the new fuel filter. it came with the tractor and is probably 30years old (you could say new old stock :clown: ) .... I wonder if its paper internals aren't allowing the air to purge through. I should have new filters turn up monday so I can verify.
 
Hi Shane.

That is a very frustatating situation to be experiencing.

I see back in post #26 that the engine has what I recognise as a CAV rotary fuel injection pump. These are usually fairly reliable.

When you said you were mowing and the engine just cut out as if you had pulled the fuel cut out knob.

I tend to concur with your thoughts, that air is entering on the suction (upstream) side of the fuel lift pump. But you said in post #261 that you have swapped and tried a different lift pump, so I tend to agree that two lift pumps won't be faulty.

Are you double sure that the work you have done with the O-rings on the fuel tank tap are fitting correctly and are not cut?

I had assumed that the fuel tank was just below the bonnet and would gravity feed to the lift pump. As the fuel tank was quite clogged up with foreign matter, maybe the fuel line to the lift pump has a restriction in it???

I am sure that you have already, but double check the copper washers or fiber washers that seal any banjo fittings. These can leak easily.

I also tend to agree that if the tank gravity feeds you might see a trace of diesel, but maybe the pressure difference is not enough to cause this.

H'mm, outside question, are you sure that the lift pump is functioning correctly against (i assume) the camshaft cam?

Cheers.
 
Hi.

I forgot to mention that the CAV injection pumps have a transfer pump at the end, unless this is sucking air??? I think not.

But I tend to think that you problem is upstream of the lift pump.

Not sure I have assisted much. Sorry.

Cheers.
 
Yes, its a very simple old deisel engine. That's why this is frustrating me so much :clown: All they need is an uncompressible fuel of some sort in the lines and it'll run. So anything but "air" will probably do. I htink I'm going to wait for the new filters to turn up before I try futher. The filter I fitted sure is decades old minimum. It sure does look nice in the tank now when I shine a torch in it though :dance:

I don't think I've ever had the thign so full of air in the past. I'm still not convinced the lift pump I swapped out wasn't introducing air (that is why everything is so chock full of air) .... I wonder if there is a simple way to test for that :)
 
CAV 296 filters are cheap.

I'd be checking the intake pipe from the tank to the lift pump for cracks, plus the fittings at each end of it.

Roger
 
Roger Wilkinson said:
CAV 296 filters are cheap.

I'd be checking the intake pipe from the tank to the lift pump for cracks, plus the fittings at each end of it.

Roger
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Yes, I ordered in some mid-week last week (oil and fuel). I was hoping in the meantime I could get it over into the shed to give it a service. I probably should change the gearbox oil and hydraulic oil while I'm at it (as its probably the original 50+ year old oil in it). But gee's, its not cheap buying that sort of quantity of oil! I also need to figure out how to fill the steering box. It appears to have stopped weeping .... which probalby means its empty :clown:

I might just swap that hard line with the line on the parts tractor. it should rule out any cracks that are hard to see that way!
 
Standard gearbox oil in the transmission if I recall. No hydraulics to require universal tractor oil. There are three drain plugs. One is under the PTO shaft. It takes 50-something litres of the stuff!

46 grade hydraulic oil in the hydraulic system, if I recall.

There is a filler plug near the top of the steering box. At the back I think.

Roger
 
DoubleChevron said:
Yes, I ordered in some mid-week last week (oil and fuel). I was hoping in the meantime I could get it over into the shed to give it a service. I probably should change the gearbox oil and hydraulic oil while I'm at it (as its probably the original 50+ year old oil in it). But gee's, its not cheap buying that sort of quantity of oil! I also need to figure out how to fill the steering box. It appears to have stopped weeping .... which probalby means its empty :clown:

I might just swap that hard line with the line on the parts tractor. it should rule out any cracks that are hard to see that way!
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Hi.

I've said it before and will say it again. I wouldn't bother with the gearbox oil, providing it looks OK, it won't stop your gearbox and won't extend it life. Keep your cash in your pocket.

Cheers
 
Whippet said:
Hi.

I've said it before and will say it again. I wouldn't bother with the gearbox oil, providing it looks OK, it won't stop your gearbox and won't extend it life. Keep your cash in your pocket.

Cheers
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Yes Shane I agree. If the oil is not contaminated then just leave it there. Those gear boxes are low stressed and no fancy gear design. No gear changes on the go either to make wear bits.
Jaahn
 
jaahn said:
Yes Shane I agree. If the oil is not contaminated then just leave it there. Those gear boxes are low stressed and no fancy gear design. No gear changes on the go either to make wear bits.
Jaahn
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I would have assumed all the metallic particles from grinding the gears for 50+ years would just settle to the bottom. So in theory, the oil will be clean'ish still (its not moisture contaminated). There will no doubt be thick layer of rubbish at the bottom of the box where its all settled. It would however be smart to change the ancient hydraulic fluid and clean its filter.

I did score a drum of FUCHS Hydraulic Oil Renolin B 68 PLUS last year on facebook marketplace. There would probably be 19litres still in it. so that would probably be fine to use.
 
Yes, that hydraulic oil will be just fine. There is a strainer where one of the hydraulic pipes goes into the front of the hydraulic housing. Undo the joiner hose on top of the gearbox and pull it out.

Roger
 
Here's the mower we all want :

Mower 1.jpg
 
Well... I finally got around to looking at the tractor again. Fitted up the new filters, bleed it and it was away .... took hardly any time at all. So there you go, if you have NOS filters around ... throw the damn things in the bin. The paper in them must turn old yellow and rock hard.... leaving you with a big unbleedable mess ere there should be a filter!

Now to move it into the shed and give it a service. For starters the new filter filter has to come off as it won't stop dripping :rolleyes: The new Oring for the middle of the filter seems to a be oversize ... and is preventing the filter fully seating in the housing.

seeya
Shane L.
 
DoubleChevron said:
Well... I finally got around to looking at the tractor again. Fitted up the new filters, bleed it and it was away .... took hardly any time at all. So there you go, if you have NOS filters around ... throw the damn things in the bin. The paper in them must turn old yellow and rock hard.... leaving you with a big unbleedable mess ere there should be a filter!

Now to move it into the shed and give it a service. For starters the new filter filter has to come off as it won't stop dripping :rolleyes: The new Oring for the middle of the filter seems to a be oversize ... and is preventing the filter fully seating in the housing.

seeya
Shane L.
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Thats good news Shane, sounds like you need to take the filter housing down to your local friendly hydraulics place and get a new "O" ring and then all should be good.
 
COL said:
Thats good news Shane, sounds like you need to take the filter housing down to your local friendly hydraulics place and get a new "O" ring and then all should be good.
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I have a few HNBR Oring sets here. HNBR shoudl be fine with diesel I'd think ( The green A/C Oring sets ). Its only taken me 12months but I've finally got council approval to throw up the leanto next to the shed as well. now I just have to find a serveyor ... and get a home builders license etc.... It would have been so much easier if I'd just build the damn thing and no-one complained to the council ( I have a nutty neighbour here that complains about everything).
 
DoubleChevron said:
It would have been so much easier if I'd just build the damn thing and no-one complained to the council ( I have a nutty neighbour here that complains about everything).
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Couldn't you give him a rusty old Citroen or something as a token of goodwill.😁
 
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Greenpeace said:
Couldn't you give him a rusty old Citroen or something as a token of goodwill.😁
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shes a bit different.... I shouldn't have started building it in view of her house.... I think its the 5meter height of the wall that I started putting up that caught the eye :rolleyes: it was going to be a 12 x 12 skillion will a row of posts down the middle. none of the shed places could do engineering on a skillion though, so now its going to be a standard 12 x 12 shed.... Oh well, gimme another year or two and I'll get there. then i just need to figure out a "free" way to get a usable floor into it :clown:
 
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