1997 Hummer H1 Transmission issues. - Hummer Forums - Enthusiast Forum for Hummer Owners


Hummer H1 The original Hummer, which brought the Hummer look to the public eye during Desert Storm, with the addition of some features that make the H1 more of a street vehicle and less of a Army truck

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Old 01-16-2013, 07:40 AM
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Default 1997 Hummer H1 Transmission issues.

Hello everyone,
I have a 1997 Hummer H1 6.5 Diesel model.

The car was static for a few years and everything was in bits and pieces, it was reassembled recently.

The issue that I am facing is that, whenever we drive the car at over 50 miles per hour, or decide to accelerate at a faster than average rate, the car would pop out of the 'H' Gear and slip into 'N'.

We tried readjusting the shift lever several times and that didn't work. We thought there might be an issue with the transfer case, so we opened it up and there doesn't seem to be anything particularly wrong, all bearings seem fine, nothing is wobbly, oil seals are fine, no visible sign of wear and tear. However, there was a decent amount of metal shaving stuck to the magnet. It used to make a bit of gritting sound when shifting gears initially, even now shifts seem very stiff.

I would highly appreciate any help as to what might be wrong in the transfer case or if the issue might be with something else.
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Old 01-16-2013, 08:24 AM
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I would find out where the shavings come from since that cannot be good
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Old 01-16-2013, 11:33 AM
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Moved so you can get some responses.

The forum Help section, is for help using the forums.... not for help with a vehicle question.
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Old 01-16-2013, 12:05 PM
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Noted, and thanks.
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Old 01-16-2013, 11:49 PM
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Come one people, I would really like to know if anyone faced a similar issue. Like I stated, there are no 'visible' signs of any wear and tear from within the Transfer case, yet some metal dust has congregated around the magnet.
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Old 02-08-2013, 12:36 PM
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You seem to be describing the transfer case popping out of position. This is VERY COMMON when the shifter fork plastic pads wear down or less commonly the shifter forks in the transfer case are wearing out. This requires a Transfer case removal and tear down.

Some thoughts in troubleshooting the issue: 1) Does your truck shift into HL or LL? When the shifter forks or pads go bad, this also becomes difficult.

2) When your truck "jumps out of gear", throw the transfer case into HL. You can do this while driving but I would only do this at a speed less than 30 mph. If all of a sudden the truck comes back to life, then it is the transfer case jumping out of gear into Neutral and not the transmission slipping while in gear or the torque converter failing.

3) Is the MIL light ON? 4L80E transmissions throw DTC codes when sick.

Gil
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Old 02-09-2013, 12:21 PM
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We replaced the forks and the fork pads a while back because we thought that that may have been the issue, but it wasn't the case. Basically it pops out of H and into N. It usually pops out at about 55 mile per hour, which isnt a safe speed to shift into HL in.

In HL and L it stays put/does not pop out and yes it does shift into them (a bit stiff though). No indicator light turns on.

Beginning to wonder if there may simply be an issue with the gear lever and its assembly... as I took apart the entire transfer case and didn't notice anything particularly wrong.
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Old 02-09-2013, 12:51 PM
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Here is the AMG check list for this issue.
It is usually the fork pads, but, not this time it seems.
I guess the next easiest thing to rule out is linkage and its adjustment.
Gil
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Old 02-10-2013, 08:20 AM
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Thanks, but I have that entire .pdf .... hasn't really been very helpful, everything seemed fine in there. The adjustment may be the issue, I tried changing it a few times, but hasn't really worked out so far.. I'll try readjusting again, maybe 12th time's the charm.
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Old 02-10-2013, 04:22 PM
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If you disconnect the shift linkage and move the transfer case range lever plate that attaches to the sector shaft by hand, does it lock in place? You need to muscle it with Channel-Locks but it can move between positions (HL - H - N) with maybe the exception of Low Lock (LL). You do this manuever when you are rebuilding a T-case on the bench. If it is very easy to move the sector shaft (abnormal), maybe the the detent spring is weak or broken. This spring is found when you remove the detent plug. It prevents the shift rail from moving position when locked into a position. This happens by the spring pushing the plunger inward to hit flat spots on the sector shaft.

I would chock the wheels, move the T-case lever into neutral using the shifter (so you know the position), then disconnect the linkage, then try moving the disconnected lever plate by hand. I would do this with engine OFF initially. If you can not move it with the engine OFF (because T-case gears are stationary since the engine isn't spinning the mainshaft and are out of alignment) , then I would put the transmission into neutral start the engine and make sure the truck does not move with the transfer case in its usual position of "H". If it doesn't move, then I would move the T-case to neutral, disconnect the linkage and try the test.

Obviously, you do not want to get run over by your truck. Doing this on a hoist with no chance of the truck moving is the safest way. Good luck.

Gil
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1997, case, gears, h1, hard, have, hummer, labor, lever, move, outback, p0723, shift, time, transfer, transmission, transmissions

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