Thread: Runaway Diesel engines

If you get a diesel leak into the sump any modern diesel can run away once it fills the sump enough that the oil thins out and becomes like water.
So it will then pump out the compressor seal or out the engine breather into the intake and start the engine running away.
I had it happen to my d2 when i brought it the head had just been rebuilt but the injector tubes had not been checked for cracks so after about 300km with the sump full of diesel the engine start to run away. Luckly i knew what was happening strat away turned the ignition off left in drive and pulled over.
Thankfully becauss i caught it at low revs and when firat started to pick up by removing the fuel injectors it shut down.

If you have injector internal valve seats fail you can also have it happen as the fuel system becomes like an old hillbourne constant flow fuel injection system, but would be easy to shut down with a fuel solenoid closing off fuel.

And yeah old gm or mechanical unit injectors if you stuff up the tune it will run away gm have the oh crap flap on the blower to block it and prevent a run away, however using it meant you had to replace every seal as tbe blower would suck them all in and stuff them

Originally Posted by lyonsy

If you get a diesel leak into the sump any modern diesel can run away once it fills the sump enough that the oil thins out and becomes like water.
So it will then pump out the compressor seal or out the engine breather into the intake and start the engine running away.
I had it happen to my d2 when i brought it the head had just been rebuilt but the injector tubes had not been checked for cracks so after about 300km with the sump full of diesel the engine start to run away. Luckly i knew what was happening strat away turned the ignition off left in drive and pulled over.
Thankfully becauss i caught it at low revs and when firat started to pick up by removing the fuel injectors it shut down.

If you have injector internal valve seats fail you can also have it happen as the fuel system becomes like an old hillbourne constant flow fuel injection system, but would be easy to shut down with a fuel solenoid closing off fuel.

And yeah old gm or mechanical unit injectors if you stuff up the tune it will run away gm have the oh crap flap on the blower to block it and prevent a run away, however using it meant you had to replace every seal as tbe blower would suck them all in and stuff them

.. good explanation.

Mercedes diesels (OM60x) sometimes develop a fault inside the pump (Bosch inline PES & RS) and leak fresh diesel into the body of the pump and thence into the crankcase thence into the breather, intake, combustion chamber 'and off she goes'.

Fortunately these lovely engines rev pretty hard (or can rev hard for a diesel) so there is a wee window of opportunity to get in there and block the intake.

Thing is, you need something handy and flat....You might try the palm of your hand but remember: You have two arms and two hands. Imagine what life would be like with half that number..

An alloy clipboard is an excellent solution!! lol

Good evening to the forum,

Well it was fortuitous that I started this item about a month ago, because guess what happened this afternoon?

I was doing a bit of tidying up on a 1989 Perentie FFR Landrover, I bought at Grays Auctions, ex Darwin.
It was advertised as a non goer, parts missing, so I knew it was a minor project.

Installed a new battery, turned ignition, nothing. Checked fuses, 3 missing, took the set from my daily drive vehicle(Perentie)
placed them in the project vehicle, turned ignition nothing, wipers worked, got out to check if the light were on, sure were.
Climbed in the vehicle ,completed the turn of the ignition again and the engine burst into life, great feeling. Sounded really smooth.

Let the motor run for a while, generator was charging well, between 12 / 14amps, temp slight movement, after about 5 minutes still no
further movement so I got a wire brush cleaned the thermostat head and wire lead, reconnected, went to 80 degree reading.
Turned the ignition off. No thing happened, tried again ,nothing happened, went to the battery disconnected both leads motor kept on running

Fortunately it was only running at idle speed. I then cut a piece of heavy cardboard following a previous suggestion on this matter, disconnected
air hose fitting and placed the cardboard across the intake vent and in about 5 seconds the motor cut out.

My next question what is the likely fault?? Being a FFR Perentie, when the radios were removed prior to auction is there any likely electrical lead
removed that maybe part of the problem. Cheers.

Fuel cut off can't be working. It's a little electric motor on driver side firewall driver side of pedal box,enclosed in a plastic bag. A pull cable runs to the injector pump to cut the fuel.

Is your perentie collection growing?

Yeah, that's not a runaway. A runaway is when the engine starts to rev and keeps going. As Pete suggested it is probably just your edic motor.

Originally Posted by rar110

Is your perentie collection growing?

Hello rar110,

Still have 4 x Perenties, but needed to satisfy myself re the amount that I would have to spend to make the FFR a goer,
At this point New Battery, 3 x fuses, and a new Clutch master cylinder. Other than that mechanically she will be 100%
The FFR is 10/1989 compliance plate, 21,440 kms, 932 meter hrs, so I would suggest it may have been a recent rebuild !


Cheers.

Originally Posted by Bearman

Yeah, that's not a runaway. A runaway is when the engine starts to rev and keeps going. As Pete suggested it is probably just your edic motor.

G'day Brian - he's not clear as to whether the edic is functioning when the starter motor
doesn't spin ... so, just wondering, if not the edic connections/ign switch it could be starter relay contacts ?

get the steel wool out