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Howdy guys.. It's cold, I'm old...Got the heater mounted, Where do I connect the hoses to the engine? Plugs can get ugly... Thanx...John

On mine, the inlet hose connects to a fitting on the thermostat housing. The return hose is connected to a fitting at the back of the head. You should have pipe plugs at both locations. Just remove them (and keep them for future use) and pick up a couple of hose bibs at your local NAPA store.

Lifer wrote:On mine, the inlet hose connects to a fitting on the thermostat housing. The return hose is connected to a fitting at the back of the head. You should have pipe plugs at both locations. Just remove them (and keep them for future use) and pick up a couple of hose bibs at your local NAPA store.

You have the hoses in reverse order. The heater inlet should be feed from the plug at the rear of the head, the hottest water is at that location. The return back into the engine cooling system should be the one at the water pump.

does it make a difference which goes where?

Mine connected on top of the thermostat and the valve is at the back of the cylinder head.

TOM R wrote:does it make a difference which goes where?

I wouldn't think so. The water is going to flow whichever way the pump wants it to go, and the heater core doesn't give a hoot which direction it flows. If you want to install an in-line shutoff valve, though, I'd put it in the hose at the back of the head.

I bought 2 5/8" ID hose nipples, 2 elbows, and 2 heater shutoff valves at NAPA. This way I could run the engine with the tub/cab removed and the heater disconnected and allows for summer shutoff. The tap at the back of the block labelled "heater" goes to the input side of the core like Charles states. The discharge/return hose connects to the tap on the top of the water pump or radiator elbow pipe fitting (if you have one which mine does). I drilled 2 holes (1 1/4in dia) in the cowl, inserted 2 PCV rubber grommets to pass the hoses to the core. I installed a Red Dot 295, 30000BTU, twin 24v 2 speed fan unit between the glove box and center vent support. I installed 2, 2 position (hi/lo) 24v switches to allow driver and passenger fan control on an L-bracket mounted under the dash. When we installed the cab, the parking brake handle contacted the side of the heater which required a few turns on the jack screw of the handle. I got it all installed and then JB offered me an original heater, so I removed all of this in order to stay original. Probably box it up and offer on epay someday. I believe the thermostat is 180 degree.

TOM R wrote:does it make a difference which goes where?

Whether or not it makes a difference depends on the heater you are using. Some designs have the flow direction specifically marked & reversing that will adversely affect the operating efficiency of the unit. Some heaters also have a vent fitting to bleed off air as the core is initially filled with coolant, this vent should be on the return flow side to work properly. Other than these issues, it shouldn't matter.

Thanks, Charles. Once again I learned something!

The only truck heaters I/ve ever played with were simply miniature ctoss-flow radiators and direction of flow didn't matter. From now on, I'll pay closer attention to what I'm doing. If there is a specified inlet and outlet, I'd want to make sure I plumbed it correctly

Thanks guys. I suspected that the plugs mentioned were correct, by hey, why re-invent the wheel! The "Bones" thank you...John

since we are on heaters here, where does the switch get mounted on the dash? and what wire# are used to hook up the blower

TOM R wrote:since we are on heaters here, where does the switch get mounted on the dash? and what wire# are used to hook up the blower

Good question! Does an "official" location even exist? On the '54 Chevy fire truck that I drive in parades, the switch for the heater blower is mounted on the upper left corner of the heater housing. No extra hole in the dash that way.

Oh...for you younger guys, the heater was an after-market accessory which was available from the dealership. It was not standard equipment. If you bought one, though, the dealership would usually install it for free.

I am installing a M-151 heater in my M37. this heater is marked with flow direction. I also have a shut off/control valve.

Should this be installed on the inlet or outlet side.

Also for the M-151 heater there is wiring instructions but it does not show the power source. I suppose you could use a hot lead of the ignition switch, I think it is wire number 85 off the B terminal.

Anybody got any other suggestions?
Hal

The orignal heater kit came w/ the switch and a mounting bracket, there is also a bracket for the def cable as well they mounted under the dash just r of center. im sure someone has a pic of theirs they can post

52m37Hal wrote:I am installing a M-151 heater in my M37. this heater is marked with flow direction. I also have a shut off/control valve.

Should this be installed on the inlet or outlet side.

Also for the M-151 heater there is wiring instructions but it does not show the power source. I suppose you could use a hot lead of the ignition switch, I think it is wire number 85 off the B terminal.

Anybody got any other suggestions?
Hal

The shut off valve is to keep hot coolant from entering the heater core, it should be installed in the head port on the engine.

You are correct on fan motor wiring, the proper connections should be in your kit to "Y" off the ignition switch terminal. 2 of the terminals are hot when the switch is on, wire #12 feeds the distributor, it's best to "Y" off the other hot terminal leaving the distributor on a circuit by itself.