M818 cab heater questions

[benders]

I am working on a M818 that didnt have a cab heater installed. I have a heater kit from an M818 that had one. My question is does it get installed inside the cab or does it install in the engine bay. I have been looking at some pics of the heaters and I get the feeling it installs in the pass side engine bay but I am not too sure. I am also wondering is there a heater control switch(my kit doesnt seem to come with one) and how many speeds is the fan suppose to have? Any help with this install would be appreciated.

Thanks

 

[Ferroequinologist]

It is installed in the passenger side engine bay. I don't have one in my 818 (yet) or I would get you some pics

There is a heater control switch, it is high, low, and off.

 

[MWMULES]

Yep it goes on the passenger side, or at least all the ones including mine are mounted there

 

[Armada]

It installs on the passenger side. The heater sets on a mounting plate that is mounted above the muffler. My 818 had no heater until I put one in it. I have a bunch of pictures of the process but can't access them at the moment. I'll work on getting them up.
The diverter box inside of the cab is opposite of an m35 div. box, as in the heated air comes in from the pass side under the dash instead of the drivers side as in the deuce. You should see a knockout on the pass side fire wall for the venting.
Some guys have put in m35 heater kits in their 809 series trucks, but mounting them on the drivers side like in the deuces, causes some challenges.
Check the TM for the 5 tons and you will find exploded views of the different parts you need so you will know what to search for. It will also let you know where to hook the coolant hoses to the engine.
Also, the heater controls for the diverter box are different between the deuce and 809 series, but the deuce controls can be made to work with the 809 diverter.

 

[benders]

Thanks for all the help guys. I think I have a pretty good idea of how the heater gets installed now. Some more pics would be much appreciated.

 

[rhinob]

I'm about to do the same install. Pics would be great.

 

[cbvet]

Just as in the M35, I recommend putting the heater under the dash on the passenger side. Heater works a LOT better as it recirculates cabin air.

 

[rhinob]

Great advice. Have a pic of the M35 system installed? Thanks mucho.

 

[zout]

I have a diverter unit that goes in the center of the tunnel at the dash area. The wrong one came in our heater kits wayyyyyy back and I just having it sitting in the garage if anyone can use it. Just pick up UPS on it and it is yours

rhinob has spoken up for the diverter - shipping it out next week

 

[benders]

So I looked at the heater kit today and tried to piece together how it bolts to the mounting plate and then how the mounting plate fits in the engine bay. I also have a round bracket that looks like it might fit around the muffler. I am not exactly sure how everything goes so if any body can help me piece the puzzle together with advice or pics that would be much appreciated. thanks

 

[zout]

do you have any pics of the pieces you are working with ?

 

[Armada]

I did a search and came up with some pics that may help you.
http://www.steelsoldiers.com/5-ton-up/24359-heater-mounting-bracket-needed.html

The diverter box I have pictured is for the M35. The 5 ton will be reversed.
Again, go to manual and you will find all the parts and #'s you will need.
Hope this helps.

 

[rhinob]

Oh my, is that diverter actually sitting on the wife's coffee table !?!?

 

[benders]

So I did some work on the heater install today. There was a round shaped bracket, it looked like it fit around the muffler. I found it was bent up. I straightened it out and i got it to fit around the muffler and bolted it up on the frame rail. so I just need to drill a couple of holes and get the mounts bolted up solid. If anybody has pics of the mounts with no heater on them that would be great. Next up the inside of the cab getting the diverter and duct work plumbed. Thanks for all the help so far.!!

 

[Rgdl]

Hello fellow 5-ton owners.

Thanks to Benders for posting the proper questions on my behalf, and even more thanks to those who have replied with assistance . He's doing some work on my newly purchased M818. The used cab heater parts I received appear to be a little different than the pics that have been posted here (ie. the fan appears to be mounted to the heater box 180° as compared to the pics, amongst other anomalies) , but he seems to be making heads or tails out of it all with SS help.

One more question: Should the used heater parts I received have come with a fan control switch? Mine did not. Has anyone used an aftermarket speed switch to control the fan? I figure the switch should have at least three positions - off/low/high.

 

[Ferroequinologist]

The switch was just a SPDT, with a resistor to drop the 24v in half when you had it in 'low' hooked to one of the power feed sides.

 

[benders]

So I have the heater bolted up solid in the engine bay now. I am going to plumb the coolant lines and finish off the work in the engine bay. I started to mock up the cab heater parts last night. I was wondering if anybody has some pics of how the heater parts look in the truck ex heater switch & vent control, diverter and the duct work. If I had a visual of how it looks it would make things a little easier. To me it looks like the diverter mounts in the middle of the cab on the firewall, then there is a elbow valve on the fire wall. There are 2 long brackets and im not quite sure where they go, im thinking they mount up in the dash area. Any help would be appreciated.

Thanks

 

[Armada]

To me it looks like the diverter mounts in the middle of the cab on the firewall, then there is a elbow valve on the fire wall. There are 2 long brackets and im not quite sure where they go, im thinking they mount up in the dash area. Any help would be appreciated.

You got it right. The 'elbow valve' mounts on the right side firewall under the dash. There should be a knockout for it. It controls the airflow from the heater to the diverter. One of your control cables will attach to that and the other control cable goes to the diverter to control floor heat/defroster.
The 2 'brackets' you're talking about sound like the deflectors for the defroster. They mount on top of the dash, one on each side, and direct the defrost air to the windows. I don't really notice a difference with them installed or note. Seems to work the same either way.
Post some pics of your install too!

 

[zout]

Here is the reversed diverter box - sending this off to a member today that was sent incorrect in out heater kits we ordered a long time ago - but here is what yours should look like: