Can a diesel run backwards?.

I have heard of this happening but never actually seen it, would be interesting.

Gday,
Never really thought much about how it works....But
Yes! They certainly can....My old 2H did!!!

Cheers

The old semi diesel 2 st bulldog tractors could run either way. In fact the early models had no reverse gear, had to slow the motor right down then as it was about to stop rip the throttle out and hope it was spinning the other way to go backwards. They develped enormous torque in relation to their horsepower.
Cheers Pete

G'day Stephen L, I had a Bulldog tractor, crank start - with the steering wheel! single cylinder, when it fired sometimes you had 3 reverses & 1 foreward, so when it started backwards you would shut the throttle off, then it would backfire, so quickly you would open the throttle a little & bingo it would be normal! I dod't think a modern diesel engine would start backwards because of the firing order, seee yaaa, aussiedingo

A diesel certainly could run backwards because I guess they don't care whether they draw air from the inlet or exhaust system. The old 2 stroke Detroit Diesels did this very well. Having said that the 4 strokes don't run backwards all that well and because now the oil pump is also running backwards I doubt they would run for very long, 2 or 4 stroke.

Cheers Pop

Stephen
Believe me a diesel engine will run backwards. I work on oil rigs and if, as you are drilling the drill bit gets stuck on the bottom but the string keeps turning it gets to a stage when the engine stalls. The entire string will spin backwards and, if you have a direct drive,
it will turn the engine over backwards. The engine will run for a short while blowing exhaust out through the air intakes and cleaners and try to suck fuel through the exhaust, I would imagine it would be the same as rolling backwards down a hill with a truck in a forward gear and your foot off the clutch.
Skip

The toyota H and 2H moors would run backwards if stalled in low range on a hill as the compression hit.
Made a big mess inside the aircleaner ;-))
They had a second oil pressure switch to shut the motor down if this happened as with it running backwards the oil pump was going the wrong way and engine damage would result if it kept going without oil.l

Hi Stephen,

As Hairy has stated, the 2H Toyota 4.0 litre six will most certainly run backwards.

The phenomenom is so well known Toyota installed a low oil pressure fuel cutout at the factory.

If the 2H runs backward it doesn't build oil pressure and will eventually sieze without oil flow.

Hence the low oil pressure cutout to shut off the fuel before any damage is done.

Geoff

as said the 2h certainly could which is why they had a low oil pressure cut out after 10 seconds to stop them doing just that.
the rotary pump of the 1HZ does not allow it to happen
dunno about nissans

certainly i seriosly doubt any modern or semi modern 4by would

Early CAT graders would run backwards for a while, CATERPILLAR fixed this by changing the the angle of the lobes on the camshaft and therefore changed the valve opening duration of the valves.
New engines, no way, electronic speed timing sensor would not savvy firing order.

Stephen,

Some are accually designed to run backwards. One of the Navys Ships HMAS Tobruk main engine can run in reverse. It has a two stage cam shaft and when reverse is selected the engine comes to a stop and hydraulic pressure shifts the position of the cam(if my memory serves me correctly) so the engine car run in reverse.

Couldnt find a link on tobruks engines sorry, maybe someone else can.

Matt

Slightly off topic, but does anyone remember the Lightburn Zeta made by the washing machine people? Depending on how you looked at it, it either had no or 4 reverse gears. To go backwards, you stopped the motor and started it in reverse, hence 4 speeds in either direction.

Interesting, but not one of Australia's great automotive moments.

Lightburn Zeta Link

"Ask to see a Lightburn!"

Cheers,
Chris

Stephen
yes they can, but only the older ones. I remember whilst I lived on King Island, and the last year I worked with the Council there.
I was on the road gang with the "2 Ikes".
This particular day Ike, the driver, rolled the old Toyota Tipper to a stop, and his foot slipped off the clutch, the truck rocked back and forth, and the motor went into "spaz mode". The only way he could shut her off was to cut the fuel off at the pump.

Interesting stuff. !

Cheers
Bucky

I remember a Case Dozer with a 301 cubic inch 6 Cyl. that if rolled down a dam wall and direction changed at the wrong time would fire in reverse..You certainly knew because the oil bath aircleaner would give a gasp and blow oil all over the bonnet..The guru's of course said it couldn't happen on a 6 cylinder and on many it would not but there were certainly occasions when it would..

G'day AQll.

The old R6 Perkins would run backwards. We had them fitted to mining trucks in the 50's, if the driver missed the gear and it rolled backwards with a load and the clutch out off she would go. The engine would rev until it self destructed (many times it happened) speed was not limited because they were fitted with a vacuum governer, the exhaust was now the intake and the govener was not getting vacuum. Bang!

The drivers were instructed if it happened they were to run around and put their foot on the now sucking exhaust pipe. You could use your hand (if it was not hot) no harm would result - this will stop any engine.

All big ships diesels run backwards for reverse. Old McDonald big (8" bore) single cylinder engines would run backwards - they were started by swinging on the flywheels, one bloke either side - if they started three times backwards we would leave it run all day using forward for reverse. One of my 2H engines did it once but only for a few seconds until the oil switch stopped her.

Interesting post, thanks

Yes, I had it happen to me...

early '70s, backing a (then new) DA series Toyota truck out of a very steep farm driveway.. got it just at stall point, next thing she took off down the hill forward in reverse gear!!
Certainly wasn't expecting that (sh@t meself for a second there;-)) but jammed me foot on the brake & stalled it before any damage was done......
I was very careful after that, to not let that engine get near the point of stalling;-))

Nissan sd series diesels also will start backwards - probably most older diesels with an inline pump would - until the low oil pressure would shut the pump off - if applicable

I saw it happen once underground at Olympic Dam.

Was in about 1989 or 1990.

An IT (integrated toolcarrier) nudged a parked 75 series (?) Toyota ute at the shaft plat (congested area).

The ute sprang to life and ROARED backwards. Within a few metres the aircleaner caught fire. It travelled backwards say 40ish metres until it went into a sump. It roared for a few seconds whilst in the sump and then stopped abruptly (presumably as water was sucked up the exhaust pipe).

It was all over within say 10 or 20 seconds. The plat and sump were adjacent to the u/g workshop. The guys pulled it from the sump and took it to the workshop. Later that shift they they got it running again after they drained the water from it. They did say it ran pretty rough though.......

It opened my eyes. I never parked a vehicle in gear for a while after that - just in case it got a nudge.