Daft question maybe, but anything to liven January up. Question is related to a previous posting in which I referred to an as-yet-unexplained 'abnormal running mode' which I experienced in a diesel car.
I know that some stationary one-cylinder engines can be started backwards, but can a multi-cylinder diesel vehicle engine do likewise?
Oz (as was)
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I don't think so, but I'm sure someone will be along soon to point us in the right direction!
Come to think of it, a 2 stroke diesel might.......
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Come to think of it, a 2 stroke diesel might.......
Certainly two stroke petrol engines can run backwards, though I guess a diesel is also reliant on an injection system, rather than reed or rotary valves and a carburettor. Reverse gear in the old Villiers 210 engined invalid carriage was obtained by stopping it, and then starting the engine to run backwards.
BTW as a point of trivia, the same basic engine was also used in class 4 kart racing, and may still be for all I know!
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I see no reason why not.but think the valve/ignition timing would have to be reversed.It has been know in the 60s to be able to do it.Doubt if modern engines would though.But you never know?
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Nah, thinking about it, I don't think it's possible. For a start the injection timing would be 'out'
Yes, petrol 2-strokes, thats possibly 'possible' if you get my drift!
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DL - That's exactly what I already wrote, if you look 'above'! ;-)
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Ah, that'll be the 'selective skim-reading' going on today!
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Correction to last post.I doubt it.But remember some engines could years ago but cannot remember what they were.
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Yes, very definitely if conventional mechanical injection is fitted. I have actually done this accidentally when starting an old Mercedes with a flat battery by rolling it down a hill, selecting reverse by mistake. Rough running and clouds of smoke from under the bonnet as the engine exhausted through the air intake. Not recommended.
659.
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Old (or current?) giant marine diesel engines, the size of a block of flats - Can't remember the details, but just a lever to change valve/camshaft gearing I think. Bottles of compressed air the size of a house to start them up (and reverse them).
(I do exagerate sometimes).
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There was a thread on this topic reference petrol engines some time back.(started by me, I think!) The conclusion was much the same - yes, given certain circumstances, but not in a modern engine with electronic timing, fuel injection, etc.
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If diesels can run backwards they will be much at it than petrol engines. More economical, better performance with all that torque, needs a different driving technique etc etc.LOL
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Martin123 is correct. All slow speed diesels fitted in large ships are able to run backwards, its the only way the vessel can go into reverse because there's no gearbox. These types of engines are all two strokes running at typically 100-200rpm. And indeed they are extremely large, if you can vizualise two or three men climbing down a ladder into one of the cylinders you get the idea. Smaller ships such as ferries with medium or high speed diesels have engines which more often revolve only in one direction. They mostly have a gearbox, not used for reversing but to reduce the relatively high revs of the engine to the speed needed on the propeller shaft which might be around 500-700rpm. Generally the engine runs at near constant revs in one direction, the speed being reduced by a controllable pitch propeller and reversing by the same CP mechanism.
In the sixties there was a small fibreglass car called the Frisky which had a two stroke petrol engine. To reverse the car you switched off the ignition and then turned it the opposite way to start the engine revolving the other way.
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There's a Sweedish pre-war diesel beloved of canal boat owners called the Bollinder - 10 or 15HP, so rather smaller than a block of flats. Some of these were not fitted with a forward/backward gearbox, but instead injected a shot of diesel at TDC which caused them to stop and go the other way. If you let them almost stall, but catch them again as the flywheel swings back the other way then they can spontaneously restart in reverse. Disconcerting!
But are you sure that the air intake was the exhaust on your Merc?
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And this reminded me of something. On www.steele3.freeserve.co.uk/stupid.html if you've nothing better to do.
'Keith: (this is an "enduring image" one, especially when you get to the truck bit)
After being knocked off my motorcycle by some myopic idiot I joined the community of bodywork protected transport by buying a three wheel Bond Minicar. It was powered by a 250cc Villiers two-stroke engine ( I was familiar with servicing these - well changing the plugs and points). The de-luxe model had a Siba Dynastart fitting on the end of the crankshaft that acted as a starter and dynamo (benefit - don't need to climb out of the passenger side (no drivers door), lift the bonnet and kickstart the engine after a stall ). This model had the engine mounted on a central pillar that
allowed the whole engine & gearbox to rotate through 180 degrees. This obviated the need for reverse gear so it could be driven on a motorcycle licence.
After a week-end servicing - cleaning up the plug and points, I set off for work. As I pulled up at traffic lights I was a bit slow dipping the clutch. The engine slowed, coughed, banged and settled down to the two-stroke approximation of a tickover. Lights change, select gear, let out clutch, REVERSE into Jaguar behind me! Bit of a shock for both of us. This is how I discovered two-stroke engines can run forward and backwards if you don't set the points correctly.'
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This reminds me of the "bubble car" I used to run years ago - a Messerschmitt three-wheeler. It had a Sachs 197 cc two-stroke engine with a Bosch Dynastart. To reverse you stopped the engine, turned the ignition key backwards and - hey presto - you now had four speeds in reverse! (It had a separate set of points for reverse.)
I took my test in mine, and was careful to explain to the examiner that the three-point turn might take a little while, especially if it turned out to be a four- or five-point turn, the steering lock not being very tight. Throughout the test, whenever I looked in the mirror, the examiner was staring around him at the inside of my little car, with its tiny cockpit. I passed first time, mainly (I think) because the examiner was far more interested in the car than in the driver.
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This reminds me of the "bubble car" I used to run years ago - a Messerschmitt three-wheeler. It had a Sachs 197 cc two-stroke engine with a Bosch Dynastart. To reverse you stopped the engine, turned the ignition key backwards and - hey presto - you now had four speeds in reverse! (It had a separate set of points for reverse.) >>
I had a German scooter called a Prior Viscount fitted with that very same engine, but the spoilsports who built it removed the reverse-run set of points! The engine sat so high in the frame that a recess was provided in the underside of the seat to house the spark plug -- hump-back bridges best avoided!
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A mate of mine once had a bond minicar. It had a separate hard top IIRC and was just the job for 3 long-haired lads in the 70's on Hayling Island. Used to have great fun turning the steering so the wheel was at 90 degress and whizzing round at a rate of knots on the spot. We hoped it impressed the young ladies but judging from our success rate, it didn't. Herald convertibles were better for that though.
I remember the rear brakes seizing on the Pompey bypass and two of us lifting the rear end up in the air so the proud owner could back off the adjusters. Who needs brakes? He ended up dumping the thing, pity because they're now worth a few bob.
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