Multifuel Heater Not Making Much Heat

[Desert Deuce]

My XM818 w/w is up in ND with Pilot (Greg). Thanks to Greg and a local diesel shop, it has been prepped for the drive to AZ. It has the multifuel fired personel heater. Greg let me know that it is not putting out the normal amount of heat. With it being about 0 degrees up there, I'm going to need a fully functioning heater for the drive. The blower seems to be working fine.

These heaters are known for very hot output.

What are the things we could look for? Filter? Any and all information would be much appreciated.

I can't find any TM breakdown or trouble shooting procedures for the heater either.

Thanks much

 

[gimpyrobb]

I have some trouble shooting guides on the PC at home, I will post up after work.

 

[Desert Deuce]

Thanks much Gimpy!

 

[steelsoldiers]

Man, those things will roast your butt. Once it is working well, you'll be riding with the windows cracked and the floor vents open

Is the air flapper opening all the way? Is it making a lot of smoke? Will it stay running once you let go of the start switch and flip it to run? Have you changed the fuel filter? Was the fuel gelled?

 

[cranetruck]

If it fires and doesn't put out, I'd check the calibration of the fuel control valve first...should be about 18 cc/min in "low" heat...many posts in the past, including cal procedure....

 

[gimpyrobb]

The clips I saved are not much help. Let me see what my manuals say.

 

[gimpyrobb]

Books not where I thought I put it. Start here and click next page at the top right:

http://www.tpub.com/content/trucks1.25ton/TM-9-2320-280-34/0579760649.htm

 

[Desert Deuce]

Thanks guys,

Chris, it could be gelled diesel, we had given that some thought. It does fire and run. it did cut out once.

Bjorn, no I didn't do a search, will do that now. That info you gave should be valuable.

Gimpy, thanks if you have a TM # I should be able to find it on Logsa or here.

 

[Desert Deuce]

Gimpy, thanks very much that's a good start.

 

[pilot]

Fuel heater

I picked up Kevin's M818 out of a heated shop; it seemed to take longer than usual to fire up the heater, (I have one in my M543a2,) but when it did it continued running. Keep in mind it was -20 F as I drove the 5 miles to town to get #1 diesel. Kept truck and heater running as I fueled up and then headed back to the farm. On high heat the truck cab was getting cooler so about 5 miles out I stopped at a restaurant to let me and the truck warm up. Same thing the last 5 miles. I could feel full heater blower but the heat was lukewarm. On my heater I would have burned my hand. Later that week I fired it up, it ran about 5 minutes, filled the cab with smoke and shut off. I opened the hood to see if there were any obstructions and then restarted. Heater continued running but changing low to high I could detect no heat change from lukewarm. Kevin and I are open to troubleshooting ideas, I don't want that Phoenix boy to freeze any body parts off on the way home.

Greg

 

[Desert Deuce]

Greg, 70 degrees here in the desert is coat weather. 120 above I can handle but -20, wow.

 

[cranetruck]

Hmmm...curious that the heater(s) keep running when there is no real heat output. There is a "flame detector" in the heaters, which will shut down the unit if there is no flame or insufficient heat. I measured the air temp out of one of my heaters once and it was about 260°F in the duct close to the heater.
There is even a warning about not defrosting the windshields until the cab is warmed up to prevent cracking the glass from the sudden blast of hot air.....

 

[gimpyrobb]

I was wondering about that too. Does it start strong and peter out? Maybe an over-temp situation? Kinda sounds like a duct is loose. Got a specific model# for the heater?

 

[mangus580]

Sounds like what mine was doing... Would fire up and run forever... and not put out hardly any heat.

then all of a sudden right before xmas... that thing started ROASTING me out of the 1009. Now I cant even leave the truck idling for too long with the heater on LOW! as it gets too hot (have even had the temp light come on for the engine once!!!)

When I first started messing with it, I had to pull the whole fuel valve apart, and clean it. Thats how I got it to at least run continuous. I suspect maybe a plugged filter. I wouldnt mess with the calibration until thats ruled out.