Archived truck rolled when parked in 1st gear

[CUMMINS4U]

i posted this in the other forum... but i need a possible explaination as to why it rolled back about 15 ft while parked in 1st gear in my drive way.



i am sure it was in 1st gear as i always creep up my drive way in first... also it was still in first gear when i discovered it and moved it back to where it was.



the truck otherwise drives fine.



thanks in advance.

 

[KB0OU]

How steep is your driveway?????????

 

[Mhannink]

i don't know just a thought it could be clutch problem maybe its not holding well or something just something to think about not saying it is

 

[CUMMINS4U]

the grade is not steep at all... 10 - 15 degrees or so.



clutch... the truck is running in perfect condition that i'm aware of.



thanks for the inputs.

 

[DBrickel]

E brake not set?

 

[Diesel Gopher]

I have had the same thing happen to me. Only goes backwards, but it does it in any gear, I tried them all. The truck by itself doesn't do this, but with either of my trailers (5,000 and 10,000 lbs aprox. ) it will do this even on a seemingly minor slope. My emergency brake is worn to the point that I needs replacement and isn't a help. I did just get a new 6 spd from dodge, and along with that I put in a SB clutch for future bombing needs. I am thinking about bringing it in and seeing what the dealer says (it's still under warrenty) but would prefer the expertise of the TDR over the dealer. By the way its a 2002 3500 4x4 NV 6spd.

Any ideas?



Matt

 

[Evan A. Beck]

E brake not set?

Always use the e-brake!

 

[AndyJohnson]

yeah new ones other than 12-v seam to roll like that very easy they'll just keep slowly inching down. Have an 03 and 05 that do it on 5spd other 6spd, had two 01's both 5spd and they do it. Currently am driving a 12-v 5spd and it takes and extremely steep incline before it tries to roll and then it just moves tell it hits compression then won't go any further.

 

[PC12Driver]

There's no reason why it shouldn't roll. Nothing is locked in place while in gear; you're only sitting against the compression in a cylinder, which will eventually leak down. Once the pressure drops, it's gonna roll. Then, hopefully, the compression rise on the next cylinder will stop the truck, but it's gonna have inertia to deal with now, too.



Another vote for the p-brake.

 

[CUMMINS4U]

There's no reason why it shouldn't roll. Nothing is locked in place while in gear; you're only sitting against the compression in a cylinder, which will eventually leak down. Once the pressure drops, it's gonna roll. Then, hopefully, the compression rise on the next cylinder will stop the truck, but it's gonna have inertia to deal with now, too.



Another vote for the p-brake.

okay... so for clarification... this is a diesel engine thing... right?



because i've never had any problems with gas engines w/manuals.

 

[PC12Driver]

Nope. Any manual transmission. Of course a 7,000 lbs truck will probably start to roll before a 3,000 pound car.



I'm not trying to be a smart (guy) when I say this, but think about it. It's not like "Park" in an auto that literally jams a fixed gear into the drivetrain. In first gear everything can still spin (reverse too). The only thing holding you back is compression, which will leak down eventually in any engine. The difference between first, and say fifth, is the mechanical advantage of the lower gears, so there's less force being exerted against the compression (but there is still force).

 

[ToolManTimTaylor]

Yep PC12Driver nailed it. Also in most cars v8-I4 you are dealing with a solid throttle plate as well. At idle running most use an idle air bypass that allows air to bypass the throttle plate when in the close position. when off the IAB is inactive thus also sealing for the most part the throttle body creating a vaccuum.



Even if you were to just leave it in gear REMEMBER if it is going to want to tend to roll backwards LEAVE IT IN REVERSE as the engine will spin the correct way when it does turn. When in First you are now in a gear that is also in a reduced ratio when compared to reverse AND it will spin the motor backwards which will open the previous exhaust valves first just aiding in cyl pressure drop faster.

 

[CUMMINS4U]

Yep PC12Driver nailed it. Also in most cars v8-I4 you are dealing with a solid throttle plate as well. At idle running most use an idle air bypass that allows air to bypass the throttle plate when in the close position. when off the IAB is inactive thus also sealing for the most part the throttle body creating a vaccuum.



Even if you were to just leave it in gear REMEMBER if it is going to want to tend to roll backwards LEAVE IT IN REVERSE as the engine will spin the correct way when it does turn. When in First you are now in a gear that is also in a reduced ratio when compared to reverse AND it will spin the motor backwards which will open the previous exhaust valves first just aiding in cyl pressure drop faster.

thanks... it makes sense to me.



because, other than the slight roll... my truck is running in perfect condition.

 

[AndrewKing]

My gasser does the same but when I put it in Granny low it holds hills better... . just a thought if you have a granny low.

Andrew