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1937 Ford Pickup
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41 Posts
Discussion Starter · #1 ·
Hello Everyone. I know this topic has been talked about many times before. I have read many posts on this subject. None of them have cured my problem. I have installed a new Mojava heater in my 37 Ford pickup. The heater is mounted under the seat. The heater hoses have a long run to the engine. I am not getting heat out of the heater. I have done all the suggested fixes, which none have helped. I am wondering if a auxiliary water pump might solve the problem. Any help on this issue would be greatly appreciated. Thanks
 

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I don't think an auxiliary pump would help. What temp is the thermostat in the engine, and what temp is it running at? Is the heater hoses insulated? If you ran metal lines, they will shed heat like a radiator.

I built a custom vegi-oil fuel tank for a van. It had internal tubing to heat the vegi-oil to make it fluid, as well as heat exchangers to get it up over 180°. I insulated all of the lines, didn't use an auxiliary pump, and it worked fine even in the winter when they went to Minnesota.

Sent from my moto x4 using Tapatalk
 

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1937 Ford Pickup
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41 Posts
Discussion Starter · #3 ·
I have installed a new 190 thermostat. My electric fan comes on at 185. It is working fine. I have checkec the temperature with a manual thermostat and it is good.
 

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Heater

Get a non-contact thermometer from Harbor Freight and shoot both lines. If the return is cool then you know there is no flow. Check to make sure there is not a restriction in the heater such as a pipe cap that wasn't removed. Is the supply hose coming off the top of the intake? Did you install a shutoff valve in the supply line and it's not operating properly? Is there a big air bubble in the line? Above all check the temps of the hoses to define the problem.



Side note, the hand held thermometer can be used for lots of troubleshooting such as which cylinder is not firing by shooting the exhaust headers or brakes dragging and bearings overheating.
 

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1937 Ford Pickup
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41 Posts
Discussion Starter · #7 ·
The engine is a ford 302. The heater hoses are connected one to the water pump intake and the other one to the back of the intake manifold. The heater plugs were removed. The valve in the heater intake hose is open.
 

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Race it, Don't rice it!
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It's been a minute since messing with one of those but I don't think that's going to work because the pump and back of the intake are both on the pressure side so that would mean little to no flow of coolant through the heater.
 

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I would run the hoses just like the stock ones would be run to a stock under dash heater. That seems to be the way heater hoses have been run for at least 70 years. Why do something different? I do not think taking water at the back of the intake manifold is a good idea. This would be taking cooling away from the head. Heater hose routing is usually from the front of the head or intake manifold before the t'stat to the heater and the return out of the heater goes to a tap on the water pump. google heater hose routing and there are many pictures of typical routings.
 

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Plumb as shown in picture below with feed to heater core coming from behind thermostat in FRONT of intake manifold. Other heater hose goes to water pump. This way, when engine is cold and warming up with thermostat closed, all coolant goes through heater core. This gives early heat and forces any air out every time you cold start. Also set up electric fan to come on at a higher temp than the thermostat otherwise the fan will run almost all the time.
 

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1937 Ford Pickup
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41 Posts
Discussion Starter · #12 ·
The previous owner put the heater hose on the back of the manifold. I will move it to the proper position on the front of the manifold and see if this solves the problem. I will change the fan thermostat to a 200 or should I go higher? The radiator thermo is a 195.
 

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Ralfareno, I see you're in Canada. Just unplug the fan and try it. This time of year you probably don't need a radiator fan at all unless stuck in heavy traffic for a fairly long time.
 

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1937 Ford Pickup
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41 Posts
Discussion Starter · #16 ·
I think I will put a 210 thermo in for the electric fan. My main fan is a flex fan. When this can't handle the heat I want the electric to kick in.
 

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Pull the heater lines from your block and just run a garden hose into them. The water should flow through the hose, core, and out the other hose. If not your core is blocked.

Start up your engine and get it 180-200 where ever your thermostat opens. Try to squeeze the upper hose. You should not be able to squeeze it or if you can very little. If you can flatten it by squeezing your not building pressure. You have a leak somewhere or the radiator cap is not sealing properly. If your not loosing coolant then the cap is probably bad. If the upper hose is cold when the engine is hot then you are missing a thermostat or it is stuck closed or you have a bad sending unit.

These are the cheap and easy things to check to start with.
 

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1937 Ford Pickup
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41 Posts
Discussion Starter · #18 ·
Well I moved the hoses to the correct positions and still no heat. I'm still thinking I need an auxiliary water pump. Help Please
 
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