You bump started a car wrong? IE, put it in reverse by mistake, rolled forward to a reasonable speed, and let up the clutch?
Could you potentially get the engine going backwards?
|
You bump started a car wrong? IE, put it in reverse by mistake, rolled forward to a reasonable speed, and let up the clutch? Could you potentially get the engine going backwards?
Yes, if it was a two-stroke, but not otherwise. (chainsaws will on occasion kick on starting and run backwards as happily as forwards)
|
Hang on a mo' - I know nowt about this but why would the engine run backwards? When you put a car in reverse the engine is still going the right way round so even if you did tow a car in reverse gear surely the engine would still rotate the right way because it's the gears which do the reversing not the engine. If the engines could operate in reverse why would you need a reverse gear? Surely someone would have invented a reverse starter so that you didn't need a reverse gear ..........Now I've confused myself with the help of the red stuff. I await being shot down in flames!!
--
Phil
|
Oh, dear - I think I see a flaw (only a little one!!!) in my point - I forgot the little matter of the direction the car is moving!
Must remember "better to be thought a fool than open your mouth and prove it"!!!
Oh, for an edit (or even better a delete) button.
--
Phil
|
In Thailand the locals use little single-cylinder diesel engines to power their long-boats.
They run them normally to go forward but, for engineering simplicity reasons, they stop the engine and start it backwards for reverse gear! These seem to run equally roughly (and smokily) both ways...
|
ISTR that a few people in early diesel Landrovers doing serious off roading managed to start the engine in reverse. No doubt it would surprise you a bit! Didn't some of the 2-stroke bubble cars work like this - to reverse you stopped the engine and then restarted it - of course a 2 stroke will run quite happily either way, still breathing in through the carb and out through the exhaust.
--
RichardW
Is it illogical? It must be Citroen....
|
|
|
They run them normally to go forward but, for engineering simplicity reasons, they stop the engine and start it backwards for reverse gear! These seem to run equally roughly (and smokily) both ways...
>>
Even surprisingly large ships such as Mersey Ferries do this IIRC
|
I do believe some of the A series engines (old Morris Minor etc) could do this.
H
|
|
Some small single cylinder 2-strokes fitted to microcars in the 50's and 60's reversed by means of stopping the engine and restarting it in the opposite rotation. Did the Villiers engine do this in Bond Minicar 3-wheelers?
|
|
I see I have repeated what Richard W said above - Sorry! (incidentally I am another 'Richard W' but not the same one!!!)
|
Phil-the car is going forward so,in reverse gear,it would turn the engine backwards.
When I worked for GPO telephones in the early seventies one of the engineers used to do this in his Anglia van .At the top of a hill he would stop the engine,engage reverse, turn the ignition on and bump start.The engine ran,but didn't sound quite right.A local car dealer used to sell these vans when the GPO had done with them,advertised as 'one owner'.No mention of the many drivers giving them serious abuse!
|
Thanks Sman - I did realise after my first posting, hence my request for a delete button!! I can only put it down to
a) Lack of thought before posting
b) My difficulty in "seeing" these things.
c) That rather swiggable red that I was sampling
d) I'm a bit thick sometimes!
Regards
--
Phil
|
|
|
|
Petrol engines where the fuel is injected or carburetted into the manifold - no, because the air flow in the manifold is going the wrong way, i.e., blowing fuel into your air filter.
Direct injection petrol engines - I don't know - I expect not because the spark would happen before the fuel was injected. I would hope that the ECU could pick up the different crankshaft / camshaft sensor phasing and inhibit the spark to prevent this.
Newer diesel engines - I doubt it because I think the pump which raises the fuel pressure for the common rail would be pumping backwards.
Older diesel engines - yes, definitely!, (OK, being pedantic, it depends on how effective the anti-reverse cams in the fuel pump are) exhaust smoke pours out of the inlet!, and for a while you have many variations on the theme of reverse gear, but can only get very limited forward motion. But, of course, you have no oil pressure, because the oil pump just dumps what oil was in the gallery into the sump - so don't do it for long.
Cracking question! - what prompted it?
Number_Cruncher
|
>>Older diesel engines - yes, definitely!, ...
I've been thinking some more about this, and there is more to add. The engine I saw running backwards had an inline fuel pump, and a diaphragm type lift pump, so nothing was sensitive to the direction of rotation. It ran like a donkey mind!!
I think that with rotary pumps, the transfer pump (the small gear or rotary vane pump inside the injector pump which raises fuel to an intermediate pressure ready to fill the main pumping elements) may be rotation direction sensitive, and so, I wouldn't expect all rotary pump equipped diesels to run backwards - the ones with rotary vane transfer pumps, like DPAs, might do?
Number_Cruncher
|
|
|
Cracking question! - what prompted it?
I'm as intrigued as you are.
--
L\'escargot.
|
|
|
|
