Blue smoke, Hitachi EX 120

newmug

Hi. I have a 1996 Hitachi EX 120 digger. Lately she's blasting out blue smoke and it keeps running when I knock her off. My theory is that she's burning oil, and that some of the oil is getting up past the rings and thats what she's running on when I turn off the engine.

This all started happening overnight. It was fine until a week ago, never burned a drop of oil. Then I let another man drive it, and its been like this since.

Now, I have a couple of questions.

1. Is it possible that the other man driving the sh1te out of it could have done damage in a few hours?
2. How can I fix this, is it an engine-out, new rings and sleeves job? Is there anthing else that can be done?
3. How long could I nurse her on before I have to fix it?
4. What further harm could be caused by driving her on?

Thanks,
Newmug

101sean

Has it got a turbo? Turbo seals going can have a similar effect although this often results in the engine revving itself to destruction running on it's own oil.

newmug

101sean wrote: »

Has it got a turbo? Turbo seals going can have a similar effect although this often results in the engine revving itself to destruction running on it's own oil.

Yea it has a turbo alright. That sounds like a horrible way for an engine to go.

101sean

Pull the hose off from the turbo to intake manifold or intercooler and see if there's lots of oil there, also see if there's excessive play in the turbo spindle (there should be some though).

Hopefully someone will come along with experience of bigger engines, I've only seen Land Rover and small diesels run away and it's very hard to stop once it happens :eek:

An excavator engine under constant load of the pumps may not do it?

One other thought which may not be applicable but on some engines failed injector seals can lead to diesel getting in the oil and until the level rises enough for the engine to start burning it. The oil would feel thin and smell of diesel.

doctorchopper

you might want to do a compression test on it, would tell you if you have a bad set of rings

Thelostcountry

I would def be going down the turbo seals road 1st, that would explain the sudden blue smoke and if she was dogged out of it. the oil scrapper ring on the piston would be wear over a longer period of time, you would have noticed blue smoke before hand.

Thelostcountry

doctorchopper wrote: »

you might want to do a compression test on it, would tell you if you have a bad set of rings

Compression test will not tell you much, you can have good/great compression
That does not mean your oil scrapper ring is good. infact sometimes with a bad oil scrapper ring, you can have excellent compression as the oil helps to seal the rings better, just like when preforming a wet test.

Pottler

newmug wrote: »

Hi. I have a 1996 Hitachi EX 120 digger. Lately she's blasting out blue smoke and it keeps running when I knock her off. My theory is that she's burning oil, and that some of the oil is getting up past the rings and thats what she's running on when I turn off the engine.

This all started happening overnight. It was fine until a week ago, never burned a drop of oil. Then I let another man drive it, and its been like this since.

Now, I have a couple of questions.

1. Is it possible that the other man driving the sh1te out of it could have done damage in a few hours?
2. How can I fix this, is it an engine-out, new rings and sleeves job? Is there anthing else that can be done?
3. How long could I nurse her on before I have to fix it?
4. What further harm could be caused by driving her on?

Thanks,
Newmug

Yep. This *100%. I've a fussy neighbour who runs a lot of ex's and he always uses the same few drivers - he lets me run machines if I need one as he says himself - "you don't dog them Pottler". Stick a bad operator on for a few hours, throttle wide open, pumps screaming and overloading the rocks out of it through pure ignorance and bad technique and you can razz the engine in hours. Slapping it off when red hot will also kill the turbo in jigg time and if yours has one, I'd say that's what is shot - have a gander at it, I'd say the seals are gone, if not, the rings are buggered. Never borrow it out unless you trust the lad 100% and then don't borrow it out either.:)

Slidey

If it is running on its the turbo, 100%

Rings and knackered valve stem oil seals are the other culprits for excessive oil burning and neither will cause it to run on.

Do not continue to use the machine, if it properly takes off you will have no way of stalling it and it will go caput as the only way of stopping it then is to block the inlet manifold

Slidey

Yep, its the turbo.

The only other normal way for oil to burn in an engine is rings/valve stem oil seals and neither would normally cause engine run on. It would be a very bad idea to continue to run the machine like this, if it properly takes off you will have no way to stall it from the cab and by the time you manage to block the air intake you will have the little man with a hammer trying to get out of your engine..

newmug

What can I do about it? Is it just a turbo-seals replacement job or would I need to get the whole turbo reconditioned? Where would you get that done?

Would an oil change help? Its fairly low on oil at the moment and it hasn't done it in a couple of days, I'm afraid to top her up in case I feed it enough oil to make it start happening again!

101sean

Listen to Slidey, he's a man who knows!

Oil change will make no difference, do not run it. A runaway diesel engine is pretty terrifying, unless you are quick and block the intake it will rev to self destruction on it's own oil in the most incredible clouds of smoke! :eek:

Spoke to a tank transporter driver many years ago who was commended for quick thinking when his engine started to run away (600hp RR Condor in a Scammell Commander), he stopped it by emptying the fire extinguisher down the intake!

Unless someone comes up with a recommendation, do a google and you'll find plenty of turbo specialists. There's nothing DIY on them as they spin at insanely high revs and are very finely balanced. Any turbo engine that's been running at high revs should be allowed to idle for a minute or two before turning off or the oil in the turbo carbonises and buggers the seals eventually.