Question about heaters

Oldsalt · Post by **Oldsalt** » Thu Apr 07, 2011 12:34 pm

Is there any source for info about heaters installed in jeeps? From what I've seen, there seem to be a lot of different ones out there. Did any of the M 38 or A1 class jeeps come with one standard, or are they all aftermarket? How about civvy jeeps? I don't think I've ever seen two jeeps with the same heater in it. The M-38A1 I'm working on had a heater under the dash. It is a small box with a hinged door to close off the heat. It has a fan on the bottom to blow through the coils. Unfortunately it looks like battery acid from the battery box above it has pretty much destroyed it. There are no tags or any other labels on it that I can discover. I'd like to replace it, but ahve no idea where to look for parts or replacements. The heaters I've seen on the various parts sites don't even remotely resemble this one. I've looked at the heater section of Downloads and none of them are close.

Any hints on where to look for info would be appreciated.

oilleaker1 · Post by **oilleaker1** » Thu Apr 07, 2011 12:51 pm

They had a hot water kind that mounted under the hood and came through the passenger side heater floor plate. Or, I've seen arctic heaters that used gasoline. They both were installed depending on need. They usually didn't have a heater. Whatever the service they were employed in mandated the option. Wes probably has the installation books with pictures of both. Civilian Jeeps used two main different heaters, one small box affair with a fan that simply blew through the coil. It hung above the drivers side petals on CJ2A's. Later they went to the Harrison heater that mounted behind the dash on the passenger side and hung so you could see the lower half. It had two angled ducts that shot heat over to the driver. Many aftermarket heaters were also installed by the owners. The one bone to pick is when BUBBA cut the dash and glovebox out of your MB or GPW to put in a heater!!!!!!

That included the data tags

John

Post by **wesk** » Thu Apr 07, 2011 2:18 pm

Cj's and MB, M38 and M38A1/M170's were all open bodied vehicles and heaters were not standard on them. They were a civvy option that could be installed by the factory and the dealer. many dealers used approved heaters that were not the same as the factory installed units so between factory installed optional heaters, after the fact dealer installed similar heaters and throw in bubba installed heaters and the list of what you can find in the CJ's for heaters is longer than your arm.

The Military had two basic personnel heater kits approved for each M38 or M38A1 or M170. They were a hot water type and a gas fired type. They used similar basic heaters between the jeep models but the installation and plumbing was quite different.

M38
1-Hot water type kit installed the heater on the passenger floor and ducted outside air to it through the tool box under the passenger seat. It then distributed the warm air via external dash ducting to the windshield and thru the round hole in the dash to a plenum for footwell heat.

2-Gas fired heater kit installed the Stewart-Warner (Southwind) heater on top of the cowl, ahead of the windshield on the driver's side and ducted the warm air thru a round hole in the windshield vent panel to similar ducting to the hot water heater kit.

M38A1
1-Hot water type kit installed the heater on the right inner fender ducted the warm air through an oval cutout in the firewall to a plenum divider mounted on the dash that fed the inner duct opening for the windshield defrost built into the dash and windshield and thru a divider plenum for footwell heat.

2-Gas fired heater kit installed on the right inner fender and used a very similar ducting arrangement to the hot water kit.

There was also a power plant arctic heat kit that used a gas heater to heat the fluid in the block and heat the special add on fluid tubes that were palced around the batteries. This kit was available to both model jeeps. It used a Perfection brand stove.

For your M38A1 project Midwest Military still offers NOS hot water heater kits. The gas fired heater kits pop up pretty regular. The hot water kit for either jeep is tough to find and expensive.

Oldsalt · Post by **Oldsalt** » Thu Apr 07, 2011 5:45 pm

Thanks for the info. This heater is a small cube that mounts entirely under the dash with water tubes through the firewall.

I kinda figured it wouldn't be easy to identify. I don't know if this was a bubba mod or dealer. The hole through the firewall is a lot bigger than it needed, and didn't look very professional. No matter whether I find a replacement heater or not, I'm going to have to repair that hole.

Thanks again,

Russell

Post by **wesk** » Thu Apr 07, 2011 7:32 pm

The square box heaters were common after market generic (one heater fits all makes) units. We carried them on the stock shelf in out tool cribs during my 22 years in the military. When a add-on box heater went tits up we just pulled two hose, one wire and 3 bolts and in went the new heater box.

I'll see if I can dig up some photos:

Oldsalt · Post by **Oldsalt** » Fri Apr 08, 2011 6:47 am

Interesting. Other than the air flow in at the top, it looks very similar to what I have. The measurements are very similar too. Since you posted this I've been searching around and found a site that sells this heater. Thanks. Now I have to decide if I want to spend nearly $200 on one. They even sell them in 24 volt versions.

Post by **wesk** » Fri Apr 08, 2011 10:12 am

Most of the several dozen of those small square heaters I installed in various assorted military trucks while I was in the Air Force had the air in at the bottom where the fins of the core were exposed to the toes of folk's boots.
If you elect to install a new one of these use the core on top type.