To get my HMMWV (M1097A2) in good running order... need help.

[DEA AK]

Park is safer and the trans does not know the difference, any reference to neutral hearkens back to the trucks with no park.
run it it forward, reverse then put it in park and check the fluid while idling.

I recall reading on a forum about a potential issue called a 'vampire' leak, where the lines between the transmission and transfer case can leak or break, causing the transfer case to overfill and remove fluid from the transmission. The suggestion was to cap off these lines to separate the transfer case, while still allowing transmission fluid to flow through the transmission cooler.

Given that I recently experienced a leak in the rubber hose off my transmission cooler, which sprayed fluid while driving, I'm wondering if capping off these lines could be a preventive measure against future problem.

 

[DEA AK]

In regard to checking and replacing tubing, hopefully avoiding failure at a future date.

These 2 larger sized tubing from the power steering reservoir feel soft to the touch, unlike a more rigid, harder to the touch tubing like the tubing connecting the power steering cooler lines.

Do they need replaced? It just feels different than the other tubing, almost sponge like.

Probably a crazy question.

 

[DEA AK]

It does appear that the TCM is not turning the MIL light on by what you describe as long as you have confirmed continuity on 567A from the light plug to the TCM, I would say for now as long as the transmission seems to be working correctly go ahead and ignore the missing light and continue to put out other fires until you get to the point you can find and swap the TCM out.

I have not been able to locate any information on this so here I am...

My 6.5 starts up fine, runs fine but lately, since its a bit warmer now, after a longer drive, and the engine is warmed up, it runs rough in gear but in P or N it idles great. I took off the air intake piece, air cleaner and tube - all were clean. New fuel filter in Sep 23', new oil, filter in Sep 23'... manual glow plug controller, new glow plugs, all fluids, tranny, coolant, etc new in Sep 23'.

Thanks for the help.

 

[Coug]

In other words, runs rough under load.
Time to start checking out the fuel system. Should have a steady stream of fuel out the filter drain in the front wheel well when running. If slow trickle then might be a blockage in the system like your check valves or fuel pickup in the tank. If no fuel and it dies (unlikely if you got it to start again after a fuel filter replacement) is bad lift pump.
That's just my initial thoughts.

When you stomp on the pedal driving down the road, do you see any black smoke out the exhaust pipe?

 

[DEA AK]

In other words, runs rough under load.
Time to start checking out the fuel system. Should have a steady stream of fuel out the filter drain in the front wheel well when running. If slow trickle then might be a blockage in the system like your check valves or fuel pickup in the tank. If no fuel and it dies (unlikely if you got it to start again after a fuel filter replacement) is bad lift pump.
That's just my initial thoughts.

When you stomp on the pedal driving down the road, do you see any black smoke out the exhaust pipe?

No smoke on start up or after stepping on the pedal. I will check out the fuel valve today - thank you.

 

[Coug]

No smoke on start up or after stepping on the pedal. I will check out the fuel valve today - thank you.

There should be a little smoke under heavy acceleration, so to me this does sound like a fuel starvation issue.

It only does it after the engine warms up a bit, or all of the time once you start loading it up?

 

[DEA AK]

There should be a little smoke under heavy acceleration, so to me this does sound like a fuel starvation issue.

It only does it after the engine warms up a bit, or all of the time once you start loading it up?

It only runs rough after it has been running for a few miles.

I would think it would be smoother but, after driving it around a few miles, it shudders a lot more in gear (under load, like you said) but when placed in P or N, it evens out nicely.

 

[Coug]

Is it just the truck shuddering, or does the engine also sound rough as well? There could be something else in the drivetrain rather than the engine being the culprit.