Dumb question: Why does it roll backwards on a hill in 1st gear?

[Bryan062087]

I have an h42 in my 62. My driveway is on a hill.. this morning I went to move my truck and like usual i left it 1st gear and the e-brake on.

I released the e-brake and while still in 1st gear I free-rolled backwards down my driveway without ever touching the clutch.

I tried it a few times more with the same result.

Shouldn't having the transmission in 1st be able to hold the truck??

 

[Mace]

low compression numbers probably.

 

[Spike Strip]

Take your foot off the clutch...

 

[Cruiserdrew]

Is it turning the motor over backwards?

 

[Bryan062087]

Is it turning the motor over backwards?

I guess, how do i know?

I'm about to give a shot at checking the compression

 

[3_puppies]

I guess, how do i know?

I'm about to give a shot at checking the compression

open the hood and see if you see any of the accessories turning.
either engine is turning or the clutch is slipping, if the clutch was slipping that bad, I would think you'd have known by now.

 

[lovetoski]

Shouldn't having the transmission in 1st be able to hold the truck??

I have never had a vehicle w/manual transmission that would stay in place on a steep hill with only the tranny & engine compression to hold it in place.

Very different from an auto, which has a lock pin.

 

[MolallaCruiser]

The compression of the engine is why they normally don't roll. Not sure about being in first gear and turning your engine in reverse as far as if it would take less compression(wouldn't think so). Suggest using E brake even though mine currently doesn't work

 

[Granite Grinder]

It's not a diesel
My 40 with a sbc will roll backwards in first gear, compression is fine, just not enough to hold back a 6,500# truck on a steep incline. The entire driveline rotates. Parking brakes are important, though admittedly, the driveline brake in the 40 sucks!

 

[Bryan062087]

Ok..tested the compression on the first 2 cylinders. Had to stop to eat dinner.. I got nearly identical results. Is it normal to get a higher # with subsequent tests?

cylinder 1: 130, 148 on the second try
cylinder 2: 130, 148 on the second try

The procedure was: warm up the engine, remove coil wire, remove spark plug of the cylinder in question, screw in comp gauge, then turn the engine over for a few seconds, look at gauge, reset gauge, then retest

 

[Cruiserdrew]

Compression looks good. I think new spec is 150 lbs

 

[Michael Hanson]

I always turn my tires into the curb. MIke

 

[Bryan062087]

7/11
3rd: 125
4th: 130
5th: 120
6th: 148
But the engine was sitting for about an hour and a half since I tested the first 2 cylinders.



7/11
1-
2- 152
3- 150
4- 150
5- 139
6- 151

 

[sirenmoses]

I always turn my tires into the curb. MIke

many driveways don't have curbs.

heck, mine doesn't even have asphalt...



way to bump post counts tho.



how steep is yr hill?
guessing this is first time it happened to you?

some rigs (my old subaru) had a hill-holder feature, but that kicked in when the clutch was depressed.

 

[Bryan062087]

Compression #'s final results:

1st: 148 (130 first try)
2nd:148 (130 first try)
3rd: 125
4th: 130
5th: 128
6th: 148

I tested the first 2 cylinders when the engine was warmed up after a 5-10 min drive. The last four were done about an hour/hour and a half later.

Could these numbers explain why my truck is moving?? Are they that low?

Any idea why 3-5 are low-er?

 

[MolallaCruiser]

The engine was not made to hold your rig from moving, use the e brake or curb or block of wood or the car behind you to hold yourself in place

 

[VTCDN]

The engine was not made to hold your rig from moving, use the e brake or curb or block of wood or the car behind you to hold yourself in place

true. Your comp is passable.
USE A E-BRAKE.

it will always do this . No worries,
and yes it was going backwards , opposite of going ..

VT

 

[Bryan062087]

To be more clear, it doesn't free roll on the hill, it rolls back unevenly i guess as it overcomes the compression of the engine on each piston stroke. The belts/accessories do turn when the truck rolls.

It's weird bc I have parked the same way in my driveway for months and I never noticed it rolling with it in 1st gear until this morning. Now, I have to pull the e-brake really tight to keep it from moving even if its in first gear.

I could have sworn the engine was holding the truck fine until this morning.. I have been parking on this same hill for months not relying on the e-brake much at all, I would barely pull it up.

What's other people's experiences?

 

[Bryan062087]

Anyone care to comment whether putting their truck in 1st is enough to hold it in place on hills etc?

 

[Bomar]

Anyone care to comment whether putting their truck in 1st is enough to hold it in place on hills etc?

No too much risk in it popping out of gear or rolling.

e brake or turn into curb if there is one.