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Runaway Diesel Linde Forklift

Runaway Diesel Linde Forklift

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eyesOpen

Original Poster:

7 posts

6 months

Wednesday 2nd August
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Hello there and thanks in advance for any help.

Had a bit a scary moment last night when my forklift's engine ran away. I'd noticed it try to run away in the past and told the guy who serviced it about it, asking for advice on cause and what to do... He said it was likely oil being sucked through the breather, and if it happens again I should run because it might explode. Well it happened last night with 2 tonnes of timber 3m in the air and this time ran away properly (the engine, not me... Although I did touch cloth). Switched it off and it was still revving its nuts off and pumping out ridiculous amounts of black smoke straight into my building. Still looked like the building was on fire half an hour later. It often puts out a fair bit of smoke on starting, but this smoke was on a whole new level.

I hopped off, and tried looking in the engine for an obvious air intake to cover up and choke the engine, but there is no obvious air intake. The hoses are nice and obvious, but the actual intake is hidden somewhere less accessible, especially when in a panic. Wanting to get away from the forklift asap, I decided I'd better move it out the way so that I could drop the load of timber. So I sat back on the ticking bomb, moved the forklift a couple of meters and lowered the pack of timber. Dropping the timber actually slowed the revs for some reason and allowed the engine to stall/stop. HUGE sigh of relief. Not just because I was still alive, but because the forklift is my single most expensive piece of equipment.

In future, if unable to shut down I will pop off the air intake hose and cover intake with piece of ply to stop the engine, but looking to solve the issue really! Could this be worn piston rings or something? Is that a big bill to get done?

Forklift is a 1996 Linde H25D-02. Noticed about a year ago that the engine oil was very thin and worryingly smelt of diesel... I thought this meant blown head gasket, but since it was running fine... if a bit smokey occasionally, I left it to it. Service engineer said he also noticed oil was thin, and also that the level was high, so pumped a bit out. No oils been added since, but I'm thinking if diesel is somehow getting in, that would thin it, and overfill it, both making it more likely to be sucked through the breather and causing runaway?

Any suggestions welcome. Happy to get my hands dirty. Technically minded, but not experienced. Who would I approach to get work diagnosed and done professionally? I'm in Shorpe area if you know anyone in particular. Don't want to use the people who did the service because they were useless. All I can think of is find another forklift service company, but wonder if there is a better option?

Also, as a side note, noticed the coolant reservoir was cold and was expecting it to be hot after running couple of hours, but now thinking maybe this is normal, with reservoir only getting hot if coolant in circulation overheats? Just looking for any possible symptoms.

Thanks again for any help!

SantaBarbara

3,244 posts

32 months

Wednesday 2nd August
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Trade it in for anew one

eyesOpen

Original Poster:

7 posts

6 months

Wednesday 2nd August
quotequote all
in my dreams

SantaBarbara

3,244 posts

32 months

Wednesday 2nd August
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How many hours has it done?

It's not safe as it is presently is it?

Bdevo3

407 posts

13 months

Wednesday 2nd August
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Possibly an injector sticking open washing the bores. Let everything settle and check the oil level. If it's higher than max and reeks of diesel I'd be looking at fuel system issues

Edited by Bdevo3 on Wednesday 2nd August 10:42

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xjay1337

9,193 posts

42 months

Wednesday 2nd August
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Diesel runaways are caused when the engine starts to run on it's own oil.

Usually on cars this is caused by turbo seals going but on a non turbocharged forklift combined with the oil becoming thin and filling up would lead me to think something with the fuel system is amiss.

I have no idea about Forklift engines so can't really be of much help but I would probably avoid using it until you have it sorted.

Mr2Mike

17,948 posts

179 months

Wednesday 2nd August
quotequote all
eyesOpen said:
Forklift is a 1996 Linde H25D-02. Noticed about a year ago that the engine oil was very thin and worryingly smelt of diesel... I thought this meant blown head gasket, but since it was running fine... if a bit smokey occasionally, I left it to it. Service engineer said he also noticed oil was thin, and also that the level was high, so pumped a bit out. No oils been added since,
If you know the oil is full of diesel, why didn't you change it? confused

A knackered injector causing oil dilution could well be the cause of this, and would also cause lots of white smoke from a cold start. Is it a normally aspirated diesel or turbocharged?

eyesOpen

Original Poster:

7 posts

6 months

Wednesday 2nd August
quotequote all
cheers bdevo3 and xjay, will have a look.

Clock says 10k hours... No idea how true that is. Not sure about safety. Once I was confident I could shut it down quickly if it happened again, I turned it back on, let it idle. Idling fine I did a couple more hours shifting timber on it. Only seems to try and runaway at high revs, i.e. when lifting fast, so babied it, keeping revs low with no more runaway. Only use it approx once a month for 4hrs, and I don't let anyone else use it.

eyesOpen

Original Poster:

7 posts

6 months

Wednesday 2nd August
quotequote all
Mr2Mike said:
If you know the oil is full of diesel, why didn't you change it? confused

A knackered injector causing oil dilution could well be the cause of this, and would also cause lots of white smoke from a cold start. Is it a normally aspirated diesel or turbocharged?
I Don't know that the oil is full of diesel, it's only my inexperienced observation. Mechanic who did service agreed it seemed thin, but didn't say anything about the smell so I assumed I was being green with regards to the smell. Normally aspirated I think.

GreenV8S

24,916 posts

208 months

Wednesday 2nd August
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If that was me I wouldn't turn the key on that until I'd taken enough covers off to give me access to block the air intake so I knew I could shut it down - and make sure that you have something on hand to block the intake and prove you can actually shut it down that way before you go any further. You're very lucky that loading the engine was enough to stall it this time - it might well not be next time. You might have a relatively minor issue at the moment, but it only needs to run away one more time to leave you with a scrap engine.

eyesOpen

Original Poster:

7 posts

6 months

Wednesday 2nd August
quotequote all
GreenV8S said:
If that was me I wouldn't turn the key on that until I'd taken enough covers off to give me access to block the air intake so I knew I could shut it down - and make sure that you have something on hand to block the intake and prove you can actually shut it down that way before you go any further. You're very lucky that loading the engine was enough to stall it this time - it might well not be next time. You might have a relatively minor issue at the moment, but it only needs to run away one more time to leave you with a scrap engine.
If you'd read my post you'd see that is exactly what I did in preparation. Ready to access and block air intake quickly. I'm not going to cause a runaway on purpose just so that I can see that suffocating the engine works. It is widely known this works already.

stevieturbo

12,711 posts

171 months

Wednesday 2nd August
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So was it actually running on it's own oil, or other ?

Surely there would be signs of oil passing the breather system ? Can you modify the intake etc so that there is no way this can happen...or at least make it very difficult ?
And check oil levels more often ?

And yep, a piece of ply somewhere to block airflow into the engine should do...but best to try and fix teh problem

227bhp

5,788 posts

52 months

Wednesday 2nd August
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I'm sure people make up new screen names and come into this section just to wind you up. biggrin

Peanut Gallery

786 posts

34 months

Wednesday 2nd August
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Aside from getting it looked at and repaired fully, at the tractor pulling event I went to a while ago, each tractor has a very simple plate is designed to be sprung into place across the air intake, held in place by a pin that is pulled out by the bloke on the trailer. - If it all goes wrong, he pulls one string, and no more air is allowed into the engine.

Cheap way to look at it - is there are crank-case breather that goes from the crank case into the intake manifold? - remove this from the manifold (bloke that hole) and put this through an oil drip catch can, if you are getting some blow by through here.

tapkaJohnD

866 posts

128 months

Wednesday 2nd August
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"Strangling" the engine was really, really successful here:

https://www.youtube.com/watch?v=WrAeUf7v49g

(Turn the sound off - stupid music)

John

yellowjack

9,589 posts

90 months

Wednesday 2nd August
quotequote all
Can't help with your forklift.

Just thank your lucky stars that it isn't a Leyland L60 engine in a Chieftain tank, sucking in the mixture of fuel and oil that's sitting in the hull through the supercharger. When one of those runs away, it's definitely time to "Runaway!" and let it go "Boom!" in peace.

I was new in my first unit when just such an incident occurred inside the tank hangar. The noise is incredible, and the smoke it generates is something else. I had no real idea what was going on at that time, so just did what everyone else was doing, and got the hell away from it...

paintman

4,091 posts

114 months

Wednesday 2nd August
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Is the fuel pump on the side of the engine & operated by the camshaft?
Possibly the pump is damaged - split diaphragm - & allowing diesel into the crankcase.
Last time I dealt with one of these was on a petrol engine & what came out of the sump was basically black petrol. Why the engine hadn't seized I have no idea & with the problem sorted & new oil & filter it was fine.

eyesOpen

Original Poster:

7 posts

6 months

Wednesday 2nd August
quotequote all
yes running on its own oil... I assume once the ignition is off, source of diesel is switched off. And you're bob on about the manifolds/breather, that's exactly where I believe it's feeding itself. So yes, the crankcase breather joins the air intake just before the air intake manifold. I've loosened the hose here so that I can yank it off in a hurry to block air intake directly at the manifold. In theory though, just yanking it off here should stop the engine since it'll no longer be getting oil as fuel. That's enough talk of yanking off... The inside of the hose here does have a small amount of oil in it. Don't know if some is to be expected though?


I too wondered about rerouting/letting the crankcase breather go somewhere else through an easily changeable filter or something, but would rather fix the problem than the symptom. That said, the rate I use this forklift, I'd probably only have to change a filter once a year, so long as the actual issue isn't doing any more serious damage, I can live with that.

Could it be the engine is overheating, causing more vapour than normal? I popped the oil cap off after it had cooled off a bit after the runaway, and noticed there was oil vapour then... Again, not sure if that is normal or not. If diesel really is in the oil, maybe this is also causing excess vapour, so fixing that solves everything. Who would I ask to investigate a fueling issue like that? I mean I could investigate, but I'd probably be better off sticking to my day job and yanking off.

SantaBarbara

3,244 posts

32 months

Wednesday 2nd August
quotequote all
yellowjack said:
Can't help with your forklift.

Just thank your lucky stars that it isn't a Leyland L60 engine in a Chieftain tank, sucking in the mixture of fuel and oil that's sitting in the hull through the supercharger. When one of those runs away, it's definitely time to "Runaway!" and let it go "Boom!" in peace.

I was new in my first unit when just such an incident occurred inside the tank hangar. The noise is incredible, and the smoke it generates is something else. I had no real idea what was going on at that time, so just did what everyone else was doing, and got the hell away from it...
Chieftain tank doesn't frighten the enemy, but it frightens. Us in Catterick

E-bmw

2,975 posts

76 months

Thursday 3rd August
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eyesOpen said:
I'm not going to cause a runaway on purpose just so that I can see that suffocating the engine works. It is widely known this works already.
What on earth makes you think you need to "cause a runaway" to try your emergency stop?

It doesn't need to be "running away" for the suffocation to work, it just needs to be running!

Yes, it is widely known that suffocating an engine works but have you got the right stuff to do it, can you do it safely, can you reach it in ahurry, you need answers to all of these questions in a controlled situation first.

As has been said already you really need to know you can do it before using it again, get it tested & have the right bit/bits immediately to hand before using it again.

You have dodged a bullet already, don't push your luck!