Possible gearbox trouble - oh woe

[Robert Wilson]

The high pressure pipe is the one that goes from the pump to the injector, usually entering from the side, the return is the one on the top.
A quick test would be to loosen the HP pipe connection and see if it leaks fuel in spurts. If so, then remove the injector and refit the tube with the nozzle facing away and retest. I repeat, do not have any skin anywhere near it as the very high pressure can blow fuel through into the bloodstream and cause severe probs.
I will have a look for pics of the engine.

Looking at Google pix, I might be wrong on the placing of the pipe, it could be the one on the top of the injector. Just follow them from the pump.

Gotcha, thanks.
I thought that was it, but just wanted to make sure.

There is also an odd little rubber pipe/hose which comes out of what looks like a bleed tap atop the injector pump.

This pipe/bleeder is attached to a union where the fuel inlet hose from the lift pump enters the top of the injector pump ​

and goes into the side of one of the injectors. It's only on one injector.

Any idea what this might be and how it might affect fuel supply?

I'll try to post a pic, but I have trouble with the technology!!

 

[Robert Wilson]

Pic of engine/injectors didn't work.
Message from "insert image" says upload failed.
I get SO angry with this facility!!

 

[DownWest]

Probably part of the spill/return. Bit odd if only on one injector. The pix on Google are a bit difficult to find things...

I did strip a Vetus twin, which I think is the same base engine, but it was a while back and vague now.

You will ptobly need a fresh washer to refit the injector and check what torque setting is required;

 

[Robert Wilson]

Update:-
Progress, albeit tentative and possibly "sideways".

I loosed the nut on the top of the injector (high pressure pipe) on first the front injector with that little pipe from the top of the pump.
The revs dropped immediately but not to the point of stalling.
I then re-tightened the nut.
I repeated this with the aft injector whereupon the engine stalled immediately.

My assumption is that the front injector is malfunctioning to some degree, because if it was perfect then the engine would have stalled, but with the aft injector still functioning correctly (I assume) there was still adequate fuel flowing to keep the engine going less quickly.

Unfortunately I didn't do the full disconnection test as discussed in posts above because when loosening the injector nuts, the unions into the pump started to weep a little and I had a problem re-tightening them.
I'm very wary of stripping threads by undertaking "DIY".

So, what does the team think?
Am I correct in assuming that the front injector is probably the problem; or the feed to it in/from the pump - or both?

Certainly vastly less than a new engine, but a new pump and injectors is about £750 plus removal and fitting*.

*Looking at the location and apparent installation I am fearful of doing it myself. I can't work out what goes where by way of mounting and bolts. It looks like a very complex nd complicated strip-down and re-assembly.

 

[earlybird]

Update:-

So, what does the team think?
Am I correct in assuming that the front injector is probably the problem; or the feed to it in/from the pump - or both?

Either assumption is possible, but the simplest, and cheapest initial option would be to remove both injectors and take them to a diesel specialist and get them tested. Shouldn't cost too much. If the both show good results, which I doubt, then perhaps turn your attention to the pump. Your injection tester should be able to offer good advice here.
Google "Kubota z482 workshop manual". This should get you a pdf of a very similar engine to yours.

 

[Robert Wilson]

Encouraging thoughts !
Thanks.:encouragement:

I shall have to be very careful loosening/tightening nuts and injectors - damaged threads, especially on cylinder head could really spoil my bank balance.
There is a pump/injector specialist in Inverness. :encouragement:

P.S. I have the workshop manual for the Z600-B which is my motor, although some of the line drawings and texts are difficult to follow.

 

[Robert Wilson]

Probably part of the spill/return. Bit odd if only on one injector. The pix on Google are a bit difficult to find things...

I did strip a Vetus twin, which I think is the same base engine, but it was a while back and vague now.

You will ptobly need a fresh washer to refit the injector and check what torque setting is required;

When at the boat this morning I had a good look at the set-up and took pics (which I can't upload - I think my 10mb limit is over-subscribed)

Briefly:-
Fuel enters pump from lift-pump. The rubber hose/bleeder tap is adjacent to this entry point.
Two steel pipes leave the injector pump and go directly and individually to the top of the injectors.
There is a link pipe from one injector to the other just atop the cylinder head entry points.
On the forward injector the tuber hose goes back to bleeder tap/

I assume this threaded fitting (which is broken),is a bleeder. It has what looks like a plunger within.

Any further views on this set-up?
Thanks

 

[DownWest]

Take both injectors for a test as early bird suggested. Takes a few minutes and cheap. As an example, a friend is having similar troubles, but worse, on a three cyl Perkins. Had the pumps and injectors rebuilt and it was £550 for all six units. Normally it is the injector nozzles that need changing and those are much cheaper than the whole unit.

Missed your last post.

The steel pipes are the HP ones that carry the fuel from the pump. The other ones are the spill or bleed past (injectors always let a bit past for lube/cooling that goes back to the tank or, in your case the lift pump). The link pipe is to let the spill from one to the other and away to the lift pump.
If the fitting is broken, might it be letting air into your fuel going to the injector pump?? Best fix that before any further tests (apart from the injectors getting looked at)

 

[Robert Wilson]

Thank you.
I shall very carefully try to dismantle them tomorrow, or over the weekend.
Gulp!

 

[DownWest]

Re the HP pipes, loosen both ends using two spanners on the pump end (one on the bit that comes out of the pump, working against the one on the fuel pipe) Don't be tempted to just undo the injector end and tweak the pipe away. That is likely to lead to sealing problems when re-fitting.

Gulp a bit of the local throat lube, takes the stress away.....

 

[DownWest]

Just reread your post and the spill line goes to the inj pump entry, or near, after the lift pump. Any leak would result in visible fuel as it should be under positive pressure from the lift pump.
You mentioned earlier about fitting a new spare lift pump. Did you do that?
DW

 

[anoccasionalyachtsman]

Reflecting on the fact that there was oil in the air filter.

I think we concluded that this really must be a result of blow by from worn piston/cylinder/rings or stuck/broken rings. Wear would be more or less even between the two cylinders.

Second fact. Cracking one injector feed stops the engine, the other does not.

My experience says that a significantly failing injector causes the engine to shake like crazy.

Putting two and two together and possibly making five. The injector test has revealed the cylinder with the broken/stuck ring. A compression test would be the usual test, but this may have saved the trouble. Stuck ring from two years out of action?

Just a thort.

 

[Robert Wilson]

Deff a possible scenario.
I'll get the injectors checked first, but due to diary/family commitments I now have to wait til mid August.
I'll try to get a compression test done in the mean time.
As to the engine shaking like crazy, I can't say I notice any unusual vibration or thumping - other than a mild wobble on start-up, but that was probably always there and went un-noticed (when everything was normal and unworrying!!)

Thank you

 

[DownWest]

My experience says that a significantly failing injector causes the engine to shake like crazy.

One would have thought so, but the Vetus(same base engine) I fixed was only on one due to a bent rod=lack of compression to fire. It was a virtually new installation, so perhaps the mounts were a bit stiffer. It did wobble a bit more, but not a lot. Could have confused it with idle wobble. ( apart from the knock were the rod was hitting the block...)

 

[NorthUp]

Re the drop in revs/ stalling when the injector pipe is slackened- this does not mean the injector is faulty (though it could!) this only proves the cylinder is not providing equal power to the other. The cause of the power loss could be a lack of compression by broken rings etc. leaking valves etc.. or a faulty injector or fuel pump, etc.
To further clarify, the slackened injector that stops the engine is the good one, 'cos its doing all the work.

 

[Robert Wilson]

Time will tell !!

 

[Robert Wilson]

Huraahhhh!! Vvvvrrrroooooommm!:encouragement:

New injectors and seals etc. Very hard to remove old ones, probably been there for thirty years. Took a LOT of bleeding through, undoing, going over everything. On and on, then suddenly it burst into life, straight up to max revs in ahead and astern. Sweet as a nut and not a tremble.
Only downside is the water temp gauge has stopped working.

MANY, MANY thanks to you all for all your ideas and encouragement.
We got there in the end - the Forum at its best.

 

[sarabande]

Virtual drinks all round, then ?


Well done, Robert, that must be a load of worry off your shoulders. Happy sailing for the rest of the season.

 

[LittleSister]

Well done for sticking at it, and very pleased you cracked it.

Shouldn’t have to worry about the injectors for another 30 years, then!

Re the temp gauge, perhaps the wiring to it has been disturbed while you were wrestling with the other gremlins?

 

[Robert Wilson]

Well done for sticking at it, and very pleased you cracked it.

Shouldn’t have to worry about the injectors for another 30 years, then!

Re the temp gauge, perhaps the wiring to it has been disturbed while you were wrestling with the other gremlins?

Thanks.
Yes, I think you're correct. but which bit of wiring remains to be identified.
I had a quick look, but can't see where the sensor is.