S-L-O-W M934 Expansable

[captcarc]

Just curious. My M934 Expansable is extremely underpowered and getting worse. I used to think that bogging down to under 40 for a very slight incline was lousy, but now it's 30. It's got the NHC250 normally aspirated. I have nothing to compare it to and am curious about other expansable owners performance experiences plus any maintenance/easy upgrade tips to try. It sounds fine, although it seems to "lope" at idle where it didn't before. I also know that the fuel is stagnant and probably due for a fuel filter change. Thanks!

 

[Scrounger]

Diesel engines do not like dirty filters, especially when they are non-turbo charged. First thing to do is replace the fuel filter. Then take it for a drive around the block. Then do the air cleaner. When one is having a problem only change one thing at a time. That way you will know what worked or didn’t. If changing the filters doesn’t help, then start looking for fuel flow issues. Start at the tank and work your way to the engine. Look for bad connections, pinched lines, clogged lines, air leaks, etc. The trucks will never be speed demons, but they will get you where you need to go.

 

[WillWagner]

Easy things first...make sure it is getting full throttle...33 degrees of travel and the lever breaking over.

 

[captcarc]

Good tips and will check...thank you very much!

 

[BKubu]

Also, run fresh fuel and conditioner through it. I once had an NA M35A2 that was a dog...absolutely no power. It had been sitting for who knows how long before it was sold through the DRMS. Well, I changed the filters and ran a few tanks for fresh fuel and Power Service conditioner through it. By the third tank, it was pulling up mountains in northern PA at 50 mph.

 

[Lukes_deuce]

I would also check fuel lines. If the truck is loping at idle, could be air in the line from a crack or bad fitting. Air in the lines would also cause the decreased performance.

 

[captcarc]

More great tips! Thank you all very much!!!

 

[papabear]

I think all the things mentioned should solve your recent loss of power, BUT....Mine ran just fine and was still like driving a cement block. I don't think I ever got mine above 50.

 

[Buffalobwana]

Have you changed any fluids recently? Transmission fluid specifically? I noticed a significant loss in power when I changed my transmission fluid to 15-40 when I first got my truck and was about to drive from Idaho to Texas. Didn’t know what was in it, and TM said 15-40 and the all knowing internet was all over the place but I settled on 15-40.

Huge mistake. Been flushing it out with Oreiley premium 10wt hydraulic fluid ever since. Made a huge difference.

The previous answers make more sense, but thought I’d throw this out there, just in case.