Diesel Running Backwards

[Zebrafive]

Had that happen with a 2 cycle HD engine in the mid 60s

If you meant Harley Davidson, they made golf carts, designed that way for reverse

 

[Beaver Cove Deere]

Blew the hat off the boss one day when the 300Plus Mack engine caught a shut down just right and fired up in reverse.

The old Detroit 2S engines where known for runaway. Our old fire truck had an emergency shut down switch that closed an air damper in the intake. In construction we knew to stuff as many rags as you could into the air intake side.

Both my 2000 Mach 1 700cc and 2020 850cc Ski Doo engines run backwards for reverse.

 

[SmallChange]

Just a thought, here -- if the camshaft is driven by a timing belt, running backwards means the tension is on the other throw of the belt, and if there is a tensioner, it is now on the high tension throw. So, if the tensioner was not sufficiently tight, it would shift, and throw off the timing. Ugly indeed if it's an interference engine.

Though perhaps no more ugly than the oil pump issue.

 

[kirkawilson]

 

[BravoXray]

The problem on an engine running backwards is at the bottom of the engine. Not only do run internal parts dry, the mainbearings and piston rod bearings may spin out of their seat. They are seated only one way with a notch in them.

Sorry, but they aren't held in position by the tabs, they are held in position by the clamping force when the rod or main caps are torqued. The tabs are only for locating them in the correct position when installed.
As mentioned by another poster, Detroit Diesels were designed to turn in either direction, as many marine applications did with twin engine installations. The rod and main bearings are the same. They could care less which direction they are turning, as long as they have a supply of oil.

 

[cqaigy2]

I had a 2 stroke motorcycle i was driving and it just died. Coasted to the side of the road. I found the problem being an open diode in the ignition circuit. Puzzled over the diode, then wired across the diode and was able to start the bike backup and go home. Ran it that way for probably a couple months, then one morning kicked the bike over and it started but sounded kinda weird. Let the clutch out and, zipped backward! I was pretty surprised, shut off the engine, then restarted it and took off forward. Fortunately i had a rectifier diode laying around and put it in place of the broken one. Never had it start up backward after that.

 

[denchen]

Years ago we had a lad with a three cylinder two stroke Saab. He sat at the traffic lights and the engine sounded strange, and when the lights changed he slammed into the car behind him.

 

[DieselBound]

Mechanical fuel pumps don't like to run backwards either. They'll do it, but you'll damage them. I don't speak from experience, just from what I've heard from top-notch diesel mechanics.

 

[CausticUrbanCoast]

Mechanical fuel pumps don't like to run backwards either. They'll do it, but you'll damage them. I don't speak from experience, just from what I've heard from top-notch diesel mechanics.

Don't basic tractor injector pumps run on a normal cam type system?

 

[DieselBound]

Don't basic tractor injector pumps run on a normal cam type system?

I'm speaking in general (others have already introduced non-tractor engines [detroit diesels]). My VW TDI pumps are NOT to be turned backwards: you can move them around a bit, but it's advised to not rotating the engine backwards for more than minor re-positioning for maintenance work). I cannot state the exact reasons why (some things you just take on faith as presented by folks who are known to be true/proven experts). All said, it seems pretty clear here that one really shouldn't look to run a diesel backwards (I'd think this good advice for most any ICE engine).