Help! My engine's running backwards...

I'm hoping someone here more mechanically minded than myself might be able to help / advise me... :confused:

First I apologise that this is not a machinery question, but instead relates to my 14 year old Petrol Mitsubishi Carrisma - in my experience the quality of mechanical advice is far better from TBN users than anywhere else on the net :rolleyes:

Today I was driving and stopped at a junction. The car often stutters a bit on tick-over, especially after driving at normal / high revs. However when it recovered from its stutter today, the engine made a terrible banging sound and smoke started to come out the bonnet. Convinced it had finally died, I attempted to move the car forwards off of the junction - but both first and second gear caused the car to go backwards!!! It was then that it occurred to me that when it nearly stalled, the engine must have somehow restarted at top-dead-centre and thrown the flywheel backwards, causing the engine to run backwards? I have never heard of this with petrol engines before (although do know it is possible with diesels)???

I immediately stopped the engine and then restarted it - everything working fine and drove me to my destination and home again (which was very lucky as I was off to get parts for our lorry which is also "broken" at the moment) :laughing:

Does anyone know what could have caused this and what I should check to make sure it's done no damage (and won't happen again)?

My gues is that the idle speed is low.

I remember a long time ago I was driving a Mack dump truck and came to a stop and as soon as I stopped I went to put it in reverse and then I noticed the engine sounded different and I remember the breather was on the right side of the cab and oil was pouring right out of it. I shut it down then started up again and it worked as it should. I was told by the other drivers that they've seen it happen many times. If I kept it running it would have dumped all its oil out of the engine via the air breather.
Your engine was just about stalled then it caught again but this time it reversed. Yep. It happens.

Many modern snowmobiles Hic up the engine and it runs backwards for reverse. So not uncommon at all. Never had a car do it mostly 2 strokes

I had a little Kubota (diesel) tractor "run backwards" about 35 years ago. It had a dead battery, we had a chain and had been on the beer........ It did not seem to hurt it.

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Originally Posted by Clint S

Many modern snowmobiles Hic up the engine and it runs backwards for reverse. So not uncommon at all. Never had a car do it mostly 2 strokes

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That is exactly my concern - with a single or two stroke I could understand it, but wouldn't have thought is possible with a four stroke until yesterday...!

Does anyone have any idea what could be done to prevent it happening again (if anything)?

Firstly, check the timing. I am guessing that the ignition is kinking in just a bit too soon, and therefore kicked the engine over backwards when it stuttered. I doubt that you did any serious damage, but keep in mind that the oil pump will not build pressure running backwards, and therefore your engine would be running without oil pressure for a breif period when it occurred.

Use to have an old Oldsmobile that would do that. Usually happened immediately after a hot shutdown. My guess tune up due.

Everybody called it "Dieseling". And the smell, OMG,,, burn your eyes out.

Diesels will run backwards. Usually after bogging down under load, compression causes them to kick backwrds. the fuel in the cylinder burns and off it goes.

Biggest worry is the oil pump is blowing bubbles in the pan and the engine will shortly burn up the bearings and throw a rod.

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Originally Posted by Willl

Use to have an old Oldsmobile that would do that. Usually happened immediately after a hot shutdown. My guess tune up due.

Everybody called it "Dieseling". And the smell, OMG,,, burn your eyes out.

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The situation you describe is completely different from, and not related to, the engine running backwards.

Dieseling - Wikipedia, the free encyclopedia

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