Another Warning: Run away Diesels

[Ruan]

I've just read a few threads recently where people have been playing with modified pumps and often having failed turbochargers and this happening and people seemingly not quite understanding the dangers of this!

Due to the way Diesels work (as I'm sure you are all aware) they do not have ANY control over the air entering the engine. This means that they are only ever controlled by the amount of fuel that is supplied to the engine by either the Injection pump or an external source... Petrols DO have control over the air entering the engine, which is why you don't see this with them (at least not to the extent of a Diesel).

The danger is that often with people modifying injection pumps you can get to a point where the governor system has been played round with to the point where it actually has no control over the injection quantity and can start running away, now usually you can notice you're on the limit of this when tuning when the revs begin to hang... But sometimes you get to a point where it's WAY too much, the engine enters a positive feedback loop (more revs = more fuel = more revs) and the engine will start taking off on it's own accord, now you'll probably catch it and turn it off quickly enough..

HOWEVER - BE WARNED - TURNING OFF THE KEY DOES NOT MEAN THE ENGINE WILL STOP!!!!!!

If you've ever taken apart a stop solenoid, you'll understand why, the spring is f*cking TINY, once you've got the engine at FULL Injection Quantity, the solenoid won't be able to drop down and kill the engine...

The other (FAR more dangerous sort...) runaway situation is where usually you've got a failed turbocharger, and the oil seal has just destroyed itself on the compressor side and is now pumping pressurized oil into the inlet manifold... Oil DOES combust VERY well in a Diesel engine... To the point where it will literally rev completely out of control...

I know this myself, I had a 6000+rpm runaway in a little village when I popped one of my turbos... No reason it won't go to 7000+rpm and the engine WILL let go after there... Usually if it's not caught within seconds you're going to do IRREVERSIBLE engine damage, as such large quantities of oil can be pumped into the engine in such a short time, almost like driving through a flood... Just hydrolocking the engine...

Now as we know, to kill combustion you've got the fire triangle...

Heat - Well you're going to struggle unless you can whip off the cylinder head and pour water over the precombustion chambers.

Fuel - Unless you can either drain the sump of oil or stop the oil pump... You're stuffed... If you're in the situation after modifying the governor, you can pull off the fuel lines, but it'll have done probably quite a bit of damage by the time it's run out of fuel...

Air - Well this is the most sure fire way really, shove a rag down the air intake, or if you've a CO2 extinguisher, let it off down the air intake... It'll stop the engine after a second or two, who cares if it eats the rag, it'll do less damage than it revving out of control...

There's one other way, that's to stall the engine - grab 5th gear, DROP the clutch and PRAY it's enough to stall the engine out... Often it's picked up enough inertia so that the clutch simply won't stop it if it's old or the engine is producing a lot of power... The only option left is the one above - shove something down the inlet...

Just be prepared as it's a situation that CAN happen, I've probably experienced a run-away 3 or 4 times and it's quite scary when it happens... I've seen engines rev off the clocks on oil...

Just when you start your engine for the first time after fiddling around with the pump, put it in 5th gear, clutch down, right foot on the brakes and start - that way you know if there's any problems you can DROP the clutch and kill the engine very quickly...

[Dan!]

Merry Christmas everybody!


Go to bed Ruan.

[Ruan]

Living the dream dude...

[Jake]

This is what my nightmares consist of...

[Bananalad]

This happened a friend of mine, engine started running on its own oil, he took out the key, nothing happened.. He reckoned he pulled a lead off the battery to stop it.. I would have loved to have seen it happen though

[Matty]

He reckoned he pulled a lead off the battery to stop it..

As you probably know, that wouldn't of stopped it...

[Bananalad]

Thats why i really wanted to be there Can you imagine the face on him if he took out the key and it didnt stop? Then when he took the lead off and it kept going?

[Connor]

The only electricity you need to run an xud is a 12v feed to the stop solenoid... But if you aunt getting your fuel from the pump, then it ain't gonna matter much

[Bananalad]

Would it be a possible that it ran out of oil when he took the lead off the battery and it was a coincidence it stopped at the same time? I didnt bother questioning him as im sure it was pretty embarrassing and ill never get the whole story

---

http://www.youtube.com/watch?v=5zx3qKX_Pno

Not a 306 but just to give people an idea of what not to do

[Matty]

Lol, I've spent countless hours searching through youtube of runaways haha. Some quite good ones on there.

Shows how it can catch you out...

I personally love the little laugh and snigger after it cuts out...

[Bananalad]

Anyone remember the episode of scrap heap challenge with the barley pickers? Think they gov moded the pump beforehand

[Choppin]

Propa job! Lol

[karl1989]

this makes me laff lol

[Ruan]

Anyone remember the episode of scrap heap challenge with the barley pickers? Think they gov moded the pump beforehand

That was an inline pump, but yeah, same principle...

[Ollie]

Anyone remember the episode of scrap heap challenge with the barley pickers? Think they gov moded the pump beforehand

Hahaha I do!! Hard to beat scrap heap challenge after you've finished your Sunday dinner lol. They had boys with fire extinguishers supervising them after that haha!

[karl1989]

is there any warning before this happens or is it just a matter of seconds and it starts

[Ruan]

Sometimes you'll get the revs slowly rising, other times it'll simply start and go out of control... Especially on oil, soon as the oil reaches the manifold it'll just take off...

[karl1989]

oh god. think id sh*t my self if it happens to me

[Diggers]

bro had this happen on a skoda octavia on the way to work.
dropped it in 5th and hit the brakes. bumped up onto the verge and walked to work.
recovered it later and new turbo next day. job done

[Jonny81191]

Dumdums sedan had a little rev when we first started it at Krisb's. Ash had the key out, stop lever on the pump did nothing, so me and Dumdum just sort of looked at each other and slammed our hands over the air intakes That stopped it, but it did eat my glove

[ozonehostile]

Dumdums sedan had a little rev when we first started it at Krisb's. Ash had the key out, stop lever on the pump did nothing, so me and Dumdum just sort of looked at each other and slammed our hands over the air intakes That stopped it, but it did eat my glove

what caused it to run away? was it the first start of the engine after maxxing out the pump?
if you do have a runaway situation what do you do to make sure it doesnt happen the next time you start it? wind the fuel screw back in?

quite concerned about it now for when i put my 11mm pump on :/

[Jonny81191]

Yeah I think someone *may* have gotten a bit over excited with the max fuel screw

And yeah all I'd suggest after that experience is to keep a way of blocking off the air into the engine, even if you can't stop it, you'll pull the revs down and buy yourself some time to find a CO2 fire extinguisher or something.

Also start with the max fuel low, if it won't start, try winding it up a bit. But don't wind it up before the first time

[Ruan]

For the record, teh stop lever will do NOTHING on the pump, to prove my point... Go rev your car to 3000rpm on the throttle, then use the stop lever and watch what happens...

It moves the leverset just enough at idle to conk it out, but by the time you've got a good amount of fuel going in, it won't do ANYTHING.

[karl1989]

what set on fire?

good job i can just pull the filter of and throw a rag through or get morrestes with a intake and shove a rag in the light

[Jake]

what set on fire?

good job i can just pull the filter of and throw a rag through or get morrestes with a intake and shove a rag in the light

I'm now keeping a rag under the seat, ready to stick into the air intake for if it ever happens!

[karl1989]

what set on fire?

good job i can just pull the filter of and throw a rag through or get morrestes with a intake and shove a rag in the light

I'm now keeping a rag under the seat, ready to stick into the air intake for if it ever happens!

already ahead of you there. was guna get some aero catches too dont think that guna happen now

[Piggy]

emergency inline butterfly????

boss did this once to a customers car...he a right idiot...faffing around, ended up refilling with oil twice....7k rpm xud AND...bang

we rang customer and said waiting on a filter...forman and I rebuilt it for collection the next day...

customer never knew!!

[Jake]

emergency inline butterfly????

boss did this once to a customers car...he a right idiot...faffing around, ended up refilling with oil twice....7k rpm xud AND...bang

we rang customer and said waiting on a filter...forman and I rebuilt it for collection the next day...

customer never knew!!

That's a bit harsh on the customers behalf isn't it?... You are the reason I don't trust taking my car anywhere.

[Dan!]

emergency inline butterfly????

boss did this once to a customers car...he a right idiot...faffing around, ended up refilling with oil twice....7k rpm xud AND...bang

we rang customer and said waiting on a filter...forman and I rebuilt it for collection the next day...

customer never knew!!

Inb4 cowboy

[strictly_perv]

Please tell us the name of your garage piggy1987 so we know to avoid it!? Not that I ever go to garages but others might.