engine ran backwards "I think"

Soundguy · Dec 18, 2004

Re: engine ran backwards \"I think\"

( if the pump can deliver fuel to the Injectors )

We had an old 60's era Cat D6-9U dozer where I work.. it very frequently ran backwards and would shower oil out the air bath filter into the operator platform.

Our old mechanic also mention about some diesels and fuel.. Says he's seen some old diesels especially detroits that 'ran away' and when he threw a choke plate on them, the sucked in a seal, and then started syphoning oil for fuel.. had to lug the engine down to kill it. That must have been quite an experience.

Soundguy

GregMVT · Dec 18, 2004

Re: engine ran backwards \"I think\"

My brother is rebuilding a 36' wood cabin cruiser with twin 327CI engines, mid 1960's model. He says one is for forward, the other for reverse and that one runs backward.

LeRoi · Dec 18, 2004

Re: engine ran backwards \"I think\"

Twin engines in boats are usually made with one running CCW rotation & one running CW rotation. The engine that runs clockwise has a different camshaft and distributor drive gear in the engine and a different gearbox and propellor.
The counter rotation keeps you from having to fight to keep the boat going straight. It wants to torque steer to the right (I think).
I don't believe it's possible for a carburated gasoline engine to run backwards without modification, because if it's exhausting through the intake, it cannot get fuel to operate.
Leroy

RickB · Dec 18, 2004

Re: engine ran backwards \"I think\"

Won't cause any long term damage except that caused by no lube oil pressure or flow. Running without oil pressure usuallly causes long term damage, unless you are real fast at doing major overhauls; then it is only short term damage.

dodgejack · Dec 18, 2004

Re: engine ran backwards \"I think\"

Thanks for the replies. I took the air cleaners off, the inside one was somewhat sooty so I changed it. DO you think the motor was hurt it ran about a minute with low or no oil pressure? Thanks again

RickB · Dec 19, 2004

Re: engine ran backwards \"I think\"

I wouldn't think so. My point was that running an engine backwards was not necessarily a harmless event.

Bobm · Dec 19, 2004

Re: engine ran backwards \"I think\"

Jack - i've had the identical running backwards phenomenon, and with the same circumstance. I suppose it doesn't matter how one goes about invoking a diesel to run backwards - if everythings at operating temp and the thing is spun in the opposite direction, off it goes. This has happened to me several times when really hammering on my Farmi, drawing the tractor too close to stall, and then quickly releasing the clutch on the winch. Its never happened with other applications like chipping wood and drawing the the engine slowly down - I'm certain that stall point, and then complete freedom to spin backwards has to be just right. At any rate, no damage has been done, and within my circle of diesel pals, no damage has ever occured if the engine was shut down in reasonably short order after the reversing.

dodgejack · Dec 21, 2004

Re: engine ran backwards \"I think\"

Thanks BobM for the informative response. I have a question about engine speed. I run around 1700 rpm-- 400 pto thinking better to bog down through the rough spots or hangups than to snap something. What rpm do you run when winching? Thank you

rockyridgefarm · Dec 21, 2004

Re: engine ran backwards \"I think\"

Sure has been an informative read - I never would have guessed any of this!

Charlie_in_TX · Dec 21, 2004

Re: engine ran backwards \"I think\"

( ( It is not possible for a 4 stroke to run backward unless it is a direct injection. If it is caburated or if there is a precombustion chamber it will not run backwards. If it is a type that will run backwards it would do so very poorly as you discribed and it would be pushing exhaust out the intake. Shouldn't do any long term damage.

For those who have had it happen on a 2stroke (diesel or gas), the intake and exhaust still operate properly, right? Just the timing is off and the shaft spins backwards.
)

Yea Right tell that to all the Cats, Mack's, BSD,Perkins, Cummin,s Detroit , That they wont run backwards . The sam heck they wont it dont make a diffrence to the injector pump how that Injector is set up to inject into the cylinder , Cummins and 2 stroke detroits , if the pump can deliver fuel to the Injectors and the rocker arm can move they will run backwards . Carburated diesel???????? Oh boy .. Yes they will run back wards and they do . 2 stroke 4 stroke it dont matter if it aint got a computer controled fuel syestem and it gets a backwards thrust on the crank they will run.. My 6.2 Detroit in my pickup will kick backwards now and then , they sound about the same either direction its 4 stroke and Indirect injection

caburated or if there is a precombustion chamber it will not run backwards Ill sit right here and bet you 1,000 Bucks thats wrong ill go out in my old VW Rabbit drift it down the drive way and catch it in reverse going forward with the key on and leave er sit their and run backwards )
Well, I guess I need to study up on the precombustion chamber and other inderect injection methods. The point that I was trying, and failed, to get across was fuel must be injected (or otherwise) into the cylinder, not the intake as is done in fuel injected and carbed gas motors. I didn't say carbed diesel, I added carbed to include gas motors into the discusion.