!987 HMMWV will not go in gear

[Reinol]

Hello all,

I am new to this and just acquired a 1987 HMMWV M998. It was running great and then I deciced to ad AC to it. I removed all the cooling radiators to get to the fan Pulley and put everything back. Now I cannot get it to go into gear. If I put it in 4 wheel drive L or H it goes into gear no problem but not in 2 wheel drive. I have changed all fluids including transmission and transfer case.

Any Ideas, please help.

thank you

 

[Mogman]

Welcome to the forum.
First it is always in FWD unless it is in neutral. it is a "full time" transfer case, you can also select HL (high lock) and low (which is locked)
Probably simple driver error, are you shutting the truck off when trying to shift the transfer case?

 

[Reinol]

Welcome to the forum.
First it is always in FWD unless it is in neutral. it is a "full time" transfer case, you can also select HL (high lock) and low (which is locked)
Probably simple driver error, are you shutting the truck off when trying to shift the transfer case?

Sorry for my ignorance but the 4W shifter shows HL H N L. When it is in N and I put the regular shifter in D or R nothing happens. It used to I believe - you have me doubting now.

Are you saying the 4W has to be in gear?

 

[GuntherRommel]

You want to be in H

 

[Mogman]

Put it in H, yes when it is in neutral it is in neutral
H= high range
HL means it is in high range LOCKED.
There is a differential in the transfer case that allows the front and rear drive shaft to move at different speeds but it is still pulling on both differentials in H
L= low range locked
HL and L should only be used off road.

 

[Reinol]

Thank you guys. I must have moved it while taking things apart and did not notice.

Thanks again.

 

[Mogman]

No problem, everyone here is happy to help.
Here is the link to the technical manuals. It is a good idea to familiarize yourself to your new toy, the operator manual is the first one and could save you time and possibly injury.

HMMWV - High-Mobility Military Wheeled Vehicle (HUMVEE)

The HMMWV is a 4x4 All-Terrain Military Vehicle introduced by the US Army in 1984 also know as Humvee. With over 300,000 units produced and in active service with 70+ countries as well as in civilian use.

www.nsnlookup.com

 

[Reinol]

No problem, everyone here is happy to help.
Here is the link to the technical manuals. It is a good idea to familiarize yourself to your new toy, the operator manual is the first one and could save you time and possibly injury.

HMMWV - High-Mobility Military Wheeled Vehicle (HUMVEE)

The HMMWV is a 4x4 All-Terrain Military Vehicle introduced by the US Army in 1984 also know as Humvee. With over 300,000 units produced and in active service with 70+ countries as well as in civilian use.

www.nsnlookup.com

Thank you

 

[TOBASH]

Sounds like you have a three speed transmission. If you forget to place tranny in neutral, she won’t start. You will curse and think something is wrong.

Drive in H and NOT HL because HL is for sandy muddy slippery surfaces.

 

[Reinol]

Sounds like you have a three speed transmission. If you forget to place tranny in neutral, she won’t start. You will curse and think something is wrong.

Drive in H and NOT HL because HL is for sandy muddy slippery surfaces.

Thanks

 

[Reinol]

Sounds like you have a three speed transmission. If you forget to place tranny in neutral, she won’t start. You will curse and think something is wrong.

Drive in H and NOT HL because HL is for sandy muddy slippery surfaces.

Actually thinking about it, She starts everytime with both in N

 

[Mogman]

Actually thinking about it, She starts everytime with both in N

The trans must be in neutral because it has no park, the truck cares not what the transfer case is doing as far as starting goes.

 

[Bulldogger]

Since you're learning about HMMWV drivetrains here I'll add a tip about driving on road versus off road:
As stated, HL and L on the transfer case are for OFF ROAD use only. H is for normal ON ROAD driving. HL and L both lock the differentials so all tires turn together with no slip between them. This is good for off road, where surface conditions very greatly, but it places considerable strain on the differentials on smooth surfaces, especially after making turns where the outside tires are moving in a wider arc of the turn than the inner side tires. This causes torque to build up in the locked differentials.
Many of us have experienced the drivetrain feeling tight and bound up after a session off road in HL or L. ---It is to be expected,
The mitigation is easy, and it is simple: every time you place the transfer case back into H after a session in HL or L, shift into reverse and back the truck up about 100 feet or so. This releases the tension in the differentials and relaxes the drivetrain.
Welcome to the club!
Bulldogger

 

[Reinol]

Since you're learning about HMMWV drivetrains here I'll add a tip about driving on road versus off road:
As stated, HL and L on the transfer case are for OFF ROAD use only. H is for normal ON ROAD driving. HL and L both lock the differentials so all tires turn together with no slip between them. This is good for off road, where surface conditions very greatly, but it places considerable strain on the differentials on smooth surfaces, especially after making turns where the outside tires are moving in a wider arc of the turn than the inner side tires. This causes torque to build up in the locked differentials.
Many of us have experienced the drivetrain feeling tight and bound up after a session off road in HL or L. ---It is to be expected,
The mitigation is easy, and it is simple: every time you place the transfer case back into H after a session in HL or L, shift into reverse and back the truck up about 100 feet or so. This releases the tension in the differentials and relaxes the drivetrain.
Welcome to the club!
Bulldogger

Thanks.