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).

 

[stevem5215]

Some engines will jump their timing chains if turned backwards. (or belt) Always follow the manufacturer recommendations to keep these types of problems at bay.

 

[Mike Madison]

The old Lanz one cylinder diesels didn't have a reverse gear. To go in reverse you stopped the engine and then kicked the flywheel in the opposite direction. Same for Yanmar one-cylinder marine diesels. They ran fine backwards.

 

[JRH02]

I saw a feature story about a ancient tractor - single cylinder two cycle diesel. It was designed with no reverse gear as it wasn't needed. To reverse the engine direction the RPMs were reduced to the point where a compression stroke wasn't completed and the "kick back" was completed in reverse. I seem to remember there was a slight compression release involved so it completed the first few rotations the other direction. It would run on many difference fuels. It was quite enjoyable to watch.

Oops - I just saw that

Mallet​

posted the video. Thanks!

 

[hawk hunter]

I saw this once when my father was pulling a heavy load on the farm with a Case 1030, he pushed in the clutch right S it was stalling and it ran in reverse, he was totally confuse and almost ran into the granary he was trying to pull, I waived and had him shut off the engine. Not sure but think the 1030 must be a 2 stroke diesel, and maybe yours may be too?

 

[RickB]

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.

DD engines were not designed to run in either direction. Unique designs allowed each engine to run in the required rotation for specific applications.

 

[rodger best]

So I discovered something I was unaware of and just wondered if this was common knowledge. When using my logging winch, and bogging it down to the point of almost stalling, the engine would start running very oddly. After shutting it down I noticed the cable was unwound and tangled inside the winch. This happened twice before I discovered why. Apparently the engine under stalling conditions can start to run backwards, taking air in from from the exhaust and exhausting through the air intake, not a good condition for the engine. And in the process running my winch backwards and tangling up the cable. Anyway, now I'm more careful about how I run it with the winch. So is this common knowledge that I somehow previously just missed?

way way back in time they would be called direct reversible. no reverse gear you shut down the motor and restarted running backward when you needed to back er down. saw one on a boat when i was a kid i belive it was an atlas. big huge pistons and about the simplest engine, my dad did a repair on it. it was pretty interesting.but yep they will run backward but need to be set up for it

 

[deberha2]

I had a 351 Mustang with EFI set up for road racing. One time I spun out on track and after coming to a stop the engine was running bad, first gear was now reverse and reverse was forward. Weirdest thing but the engine was probably running backwards. Shut it off and restarted and all was good.

 

[OTHill]

I ran an 80 JD diesel as a teenager and if you lugged it down to the very last pop and pulled the clutch it would start backwards. At that time I thought it was kinda cute. Never seemed to harm the engine.

 

[LibraryMark]

I have an army deuce-and-a-half truck that I bump started once while rolling backwards down my driveway, but I didn't take into account that I would have to put it in reverse to pull if off. Sure, it ran, but all my forward gears now acted very strange and black smoke was coming out the air intake. I shut it down quickly and thought about it for a little bit then felt very stupid.

 

[mike peyerl]

So I discovered something I was unaware of and just wondered if this was common knowledge. When using my logging winch, and bogging it down to the point of almost stalling, the engine would start running very oddly. After shutting it down I noticed the cable was unwound and tangled inside the winch. This happened twice before I discovered why. Apparently the engine under stalling conditions can start to run backwards, taking air in from from the exhaust and exhausting through the air intake, not a good condition for the engine. And in the process running my winch backwards and tangling up the cable. Anyway, now I'm more careful about how I run it with the winch. So is this common knowledge that I somehow previously just missed?

I've had that happen a couple times now I set the cable lock when I'm pulling hard and it won't let it run backwards