M1123A2 engine noise while traveling on highway.

[Creed]

Hey guys. Drive my hmmwv on highway for first time. I got an astounding 49 mph. While coasting my engine gets really loud for a while, dies down and then starts again. Is that normal. Its seems a fan or RPM just gets really high and can hardly hear anything in the cabin. I will post a video. Hopefully you can hear the difference.

 

[Creed]

Hey guys. Drive my hmmwv on highway for first time. I got an astounding 49 mph. While coasting my engine gets really loud for a while, dies down and then starts again. Is that normal. Its seems a fan or RPM just gets really high and can hardly hear anything in the cabin. I will post a video. Hopefully you can hear the difference.

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[Milcommoguy]

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Sounds like ?? Could just be the fan kicking in. Normally would run a little longer. Is the temperature guage following the hotter to cooler when cycling?

Sorry, more questions than answers.

Strap in... ready for take off, CAMO

 

[Mogman]

That is the fan kicking in towards the end of the video if that is what you are talking about, it does also seem to be running quite a few RPMs for 50MPH.
Is it shifting or are you running along in 2nd gear?

 

[Creed]

Sounds like ?? Could just be the fan kicking in. Normally would run a little longer. Is the temperature guage following the hotter to cooler when cycling?

Sorry, more questions than answers.

Strap in... ready for take off, CAMO

Its stays at 220 the whole time.

 

[Creed]

Its stays at 220 the whole time.

Also 49 mph is horrible. I was thinking of this turbo vs. a swap. Lot less money. What do you think?

 

[MarkM]

LoL yep that is our quiet cooling system fan alerting us it's on the job.

Mark

 

[Mogman]

I think you may be running in limp mode, again is the transmission shifting? no real difference in the turbo, horsepower difference is very marginal.

 

[Mogman]

Also is does not sound like you are "coasting" the only time you coast in a HMMWV is occasionally downhill.
Could you mean while cruising?

 

[Creed]

Also 49 mph is horrible. I was thinking of this turbo vs. a swap. Lot less money. What do you think?

That is the fan kicking in towards the end of the video if that is what you are talking about, it does also seem to be running quite a few RPMs for 50MPH.
Is it shifting or are you running along in 2nd gear?

Have in overdrive and H.

 

[Coug]

if the max you can do is 49mph then either you're stuck in limp mode (2nd gear) or you have a power output issue.


Does it feel like it's shifting gears at all?

 

[MarkM]

After listening to the video it sounds like you are only in 2nd gear and the fan should stay on like 2 min. Try shifting the gears manually and see if you are shifting properly.

Mark

 

[Creed]

That is the fan kicking in towards the end of the video if that is what you are talking about, it does also seem to be running quite a few RPMs for 50MPH.
Is it shifting or are you running along in 2nd gear?

I don't feel it shifting. Is there anyway to know for sure?

 

[Creed]

After listening to the video it sounds like you are only in 2nd gear and the fan should stay on like 2 min. Try shifting the gears manually and see if you are shifting properly.

Mark

Ok. Will try

 

[Mogman]

Do you have a lit trans light when you turn the ignition to run? If not it is likely your TCM is not getting any power.

 

[Mogman]

It should be quite obvious if it is shifting or not, when in limp mode it would seem to bog a little on takeoff (starting in second instead of 1st) and then it does not shift, thing makes too much noise not to notice when it shifts.

 

[GuntherRommel]

getting to 49 mph in limp mode would blow something up and makes me cringe just thinking about above 35. Balls out in 2nd gear

 

[frauhansen]

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Added video. Let me know what you think. Thanks.

Thats your fan thats kickt in...

 

[Creed]

Do you have a lit trans light when you turn the ignition to run? If not it is likely your TCM is not getting any power.

Do you know the wiring numbering for TCM relay and disconnect? I attached photo.

 

[GuntherRommel]