Diesel engines loosing power

[jem]

I built a digger full size which has a Kobota 3 cylinder Diesel engine everything is going fine for a few minutes, then it loses power, and almost comes to a standstill,revs drop to very low, or sometimes it stops!
and then it picks up again and works for some more minutes. this occurs whether it is under load, or not. It is not overheating.

I wonder if any kind person could come up with some suggestions. I looked at an injector, and it seemed ok, though I know very little about diesel engines!

best wishes

Jem

[gwr14xx]

Try running it with the fuel cap off - the tank breather may be blocked.

Regards,
Eddie.

[ettingtonliam]

How long since you changed the fuel filters? They don't cost very much, blow the pipes through, drain and refill the tank and change the filters.

[JonL]

Are any of the fuel lines transparent? That can be helpful for checking for air getting in.

[jackrae]

You haven't stated whether the engine has a separate fuel injection pump or direct cam operated injectors. Assuming the former , apart from the previous suggestions of fuel starvation, the problem might be air in either (or both) the injector pump or injector feed lines. The injector pump should have a vent valve to remove air. To eliminate air in the injector feed lines you could do it with the engine running. This technique was often used to identify faulty injectors but could also be used to expel entrained air. Lightly loosen each injector feed line in turn. Any air in these lines will then be expelled by the pressurised fuel. However, be advised that the fuel pressure could be several thousand psi so may spray out as a very fine high pressure mist which can easily penetrate skin.

[jem]

Hi Everyone, I guess that I have put this in completely the wrong heading sorry. Thank you all very much for your suggestions, this does give food for thought. I haven't checked the fuel filter, so that is the first thing to do.I will also check the vent in the fuel tank. As I said, I did get one injector out, but they are very tight in there cylinders, so I really need to get a 22 mm long socket, in order to unscrew them.I have been using the digger today, and it is a bit better, so perhaps I have got rid of some air in the system?

I will do some more investigating tomorrow,

thanks once again

Jem

[JonL]

I've heard its worth undoing injectors while the engine is warm as they are incredibly easily sheared off, and this reduces this risk apparently. Lots of plus-gas and a sensitive touch!

[goldstar31]

Red Dust from the Sahara??

Saludos

Don Norman

[jem]

Thank you very much for that tip Nobbysideways, It would be a real desaster if one did shear off!!!

yes we do get plenty of sahara sand, but not enough to make a beach next to our garden.

If anyone is in Mallorca holidaying do drop in as it would be great to meet fellow engineers

best wishes

Jem

[goldstar31]

I assumed that the normal routine services had been faithfully carried out and , because, I had property nearby in Menorca until recently, merely addeda local variable.

My little Skoda car has stopped with a unexpected variable in that with insurance restrictions as I have now entered the run or scrawl up to my 90th year, that I wasn't running about in it much and the battery wasn't being charged sufficiently to turn diesel compressions over!

So reminded yesterday my other car , a Merc SLK230 has reached its 20th birthday.

Havingg messed about with mechanical things for 80 years, I must conclude there are variables in people too.

'Nuff said!

[jem]

Hi Everyone, stupid me, it was the fuel filter that caused the problem, the first thing that I should have checked, still thanks to your help the problem is now sorted, and the digger is running very well once again.

very best wishes

Jem

[JonL]

Just glad it was a simple fix. Would be worth investigating what has caused the filter contamination though.

[goldstar31]

Jun 19, 2019 17:20:38 GMT JonL said:

Just glad it was a simple fix. Would be worth investigating what has caused the filter contamination though.

In my vast experience of the vagaries' of life in the Med, I'd put it to two.factors. One of which is airborne Saharan sand and the other is liquid Mediterranean salt air that mixes with the aforesaid and turns what hasn't already been contaminated, into a pleasing shade of rust.

The humidity which gets into more things than diggers, iill avoid the Normal rusing of car sills but will effectively rot the the A and B posts so that what. was once a sedate little Seat 5 or 600 into a quite interesting top less sports car. Then the water which has wondered its way from the French Alps glaciers into hard limestone which bungs up the local sewage system so that the one pipe seawge system of fresh water by day in a sewage out at night ceases to function using the wet string electrical supply that fails on any month without a 'z' in it.

Maybe Jem has a different version of events but my late wife was the one who grew palm trees by planting them -in the septic tank and inviting those who were not close friends to eat the dates! A sort of getting one's own back.

Don Norm

[jem]

I am afraid that the main cause of contamination, was not replacing the filter earlier.I bought a scrap road cleaner some years ago, which I took to bits and then built a digger with it, and although I cleaned the diesel tank very thoroughly, I didn't change the fuel filter, it had probably spent years cleaning up sahar sand from the streets of Manacor, plus humidity and everything else lurking on the streets, so completely my fault, anyway the digger is working very well now, makes life much more pleasant than using a shovel and pick, at the moment you cannot even get a fork in the ground, its so hard, we don't get much rain here!!!

best wishes, and thanks everyone

Jem

[dfh]

It could be diesel bug if it has been knocking around for a while, especiaaly if the old fuel contained biodiesel, if you do a search you will find what might be found in the filter due to diesel bug. These days a lot of people with narrowboats use an additive to combat it as do I.
David