# Diesel engine cranking backwards??? Help



## Huntinfamily (Aug 14, 2010)

I just put 6.2 diesel back in my truck after rebuilding it. Here's the problem, the starter is cranking the motor backwards. Instead of the motor turning to the right (sitting in the drivers seat) it is turning to the left. The engine did fire but blew the exhaust through the intake. I know the old detroit motors will run backwards which is what this is doing. Only thing I can think of is that I put the purple wire on the starter on the wrong side. Any thoughts would be appreciated. I am going to go drop the starter now but i am sure I put it on the correct side


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## agmantoo (May 23, 2003)

Are you judging the engine rotation by the direction the fan is turning? If so, on some Ford engines with the serpentine belts the fan will rotate CCW. Check that out before proceeding with the starter. Post your findings. PS....all old engines turned CW facing the engines, not from the drivers seat.


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## ace admirer (Oct 5, 2005)

the combustion cycle of a two cycle will allow it to run backwards with very bad results...the oil pump will not be working....of course the blower will be running backwards which means the engine will not be charged with air other than what is drawn in from the down stroke of the pistons....which is probably a good thing

is the metering pump timed correctly? 

it seems that the starter bendix would kick out if the starter were running backwards,,,unless the solenoid is stronger than i think it is.

would like to hear the results of this one...


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## Ray (Dec 5, 2002)

I don;t know the engine but most diesel engines will run backwards, some have stops, like one way pumps that cause damage in running backwards and some run just fine. the Detroit you can move the crank to either side and run it which ever way you need, older Bolens, kubota etc., and some others will simply start up backwards from a backfire or kill it and roll backward down a hill and pop the clutch and it will start in 4th gear backwards and go like all Hell.
As there are so many different configurations on diesel engines that aren't electronic, I suggest you go to an diesel forum that have members that work on your old engine, they have time and have intimate experience as there are so many different scenarios, with IP shafts, pump shafts, chain drives, crank shaft placement for opposite rotation, on and on. These diesel forums love to help a fella out. and can quickly, good luck, ray


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## oneokie (Aug 14, 2009)

There is no way the starter should be cranking the engine in the wrong direction. Only way that can happen is if the bendix is locked up and you got the battery cables reversed. The overrunning function of the bendix would not allow it to turn the flywheel backwards if you had reversed the battery cables.

Are you sure you got the timing correct when you put the cam/injection pump back together? Are you sure you have the static timing of the injection pump correct?


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## Huntinfamily (Aug 14, 2010)

OK. This is what I figured out. I should never never never stay up all night trying to race and finish working on anything. The motor was not turning backwards. It was turning the correct direction. I still haven't figured out what the popping sound I heard was. Could have been either a lifter that needed oil or maybe a injector that had some air in it. After a good long nap I went back out and finally got the truck started. It ran rough for the first minute or so then smoothed out. When I took it for it's first test drive it had a loud knock (like a rod knock) but that went away after about 30 seconds. I guess I was being really paranoid because I have never rebuilt a diesel before and this is now our only vehicle until we can save up for a second car. Thanks everyone for your advice. I remembered my Grandfathers diesel tractor running backwards when the motor bogged down real bad and I guess in my exhausted mind I thought my motor was turning backwards.


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## ace admirer (Oct 5, 2005)

sometimes a injector that is not atomizing properly will cause a knock that sounds,,,,,well it sounds baaad.....

and,,,,,, as someone that has spent their whole life burning the candle at both ends and the middle.(working two and three jobs that is) i know how you feel.


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