Transmission experts, help me find the problem...

[thedeliverator]

The transmission in my M1009 has been acting up a bit lately, and I'm hoping I can figure it out before the solution becomes expensive.

Symptoms I've noticed are a lot of chattering at idle and low RPMs when it's cold. No noise in neutral, seems to smooth out at higher engine speeds. Happens both when moving and when stopped in gear. Once I've driven a few miles, noise goes away.

I checked the transmission fluid level, and it seemed okay, but should I be checking cold or warm?

It's about due for a fluid change, since I've had it 18 months and I'm uncertain as to when exactly it was last done. Since I have to drop the pan anyway, are there any early warning signs/things to check while I'm in there?

 

[Goatwerks]

Which trans do you have? If it is a 700R4 there are a few things to check, look in the pan for clutch or metal debris. Look at the reaction drum surface for discoloring or metal to metal contact(worn 2-4 band). Chattering in gear is usually a sign of worn out friction materials.

 

[CARNAC]

If you've had the vehicle for 18 months and have no idea when the fluid was last changed, change it immediately. Drop the pan and throw it away. Get one of the newer pans for the HMMWV that has the drain plug in to simplify life in the future. It's a start.

 

[Rattlehead]

If it makes noise when in gear and stopped, the only things turning in the trans are the torque converter and the pump. Try shifting to reverse and/or low 1st and see if the noise changes. Those ranges in most transmissions are at higher pressure.

I am thinking that it could be something else making the noise, other than the trans?

Change the fluid anyways if you don't know the history. Always check fluid level when its hot.

 

[mangus580]

Loose Torque Converter Bolt

 

[1956_4x4]

Or a cracked flex plate...

Smitty

 

[86M10086.2L]

where can you get a hummer tranny pan? I'm looking at a fluid/filter change soon, and having a drain plug sounds good to me.

 

[mangus580]

where can you get a hummer tranny pan? I'm looking at a fluid/filter change soon, and having a drain plug sounds good to me.

B&M makes a drain plug kit thats pretty cheap, and simple to install.

 

[thedeliverator]

Thanks all for the suggestions!

Did some further testing today - noise is louder in reverse than in other gears, and it IS present in Park and Neutral - just not loud enough for me to hear when it's out in the yard. In the garage, though, I can just hear it over the engine.

How would I check for a loose torque converter bolt/cracked flex plate?

 

[Goatwerks]

Pull the inspection cover and use a light to see the flexplate , they tend to crack around the crank bolt area. Look for rust lines(usually a crack) and check converter bolts .

 

[AJMBLAZER]

As to the HMMWV trans pan with the built in drain plug...you can't find them...anywhere. Looked for about two months a while back and found NADA including hassling anyone on eBay selling HMMWV parts, surplus parts, transmissions, transmission parts, etc etc etc along with all of the surplus dealers I could find. No one has them.

The transmission plug kit mentioned above is going to be my solution when the fluid gets changed this coming year.

 

[CCATLETT1984]

ajm, why not ask Ted. I bet he'd know where to get one, or emmando22.