More heat to heater core.

[rsh4364]

Since the 2 rear cylinders are the hot spots in the coolant system would it be beneficial to run a rear cylinder head bypass system right in to the heater core input? A few years ago I had read somewhere about the rear cylinder head bypass system and I found the threaded plates that bolt on the heads, they have 1/2 npt threads,then bought a few 1/2 npt to hose 5/8 barb fittings and a few four seasons #84757 coolant y fittings.figured I would plumb into the heater return line,then considered going right to heater core instead. Any ideas, suggestions or thoughts welcome. Thanks.

 

[rsh4364]

Input welcome.

 

[rosco]

Often what happens with these radiator type heater coils (assuming everything is in good working order), is the coolant passes through the radiator too fast, before maximum heat is radiated. The solution can be installing another heating radiator in series - in the same case perhaps, or even a whole additional heater. Additional tricks can be meticallously plugging up air leaks, increasing coolant flow with a circ pump, or as you mentioned, increase its temperature. I did all of the above in the transport truck seen in my avatar, before I was happy with the comfort level, since I had a penchant for going to the "Beach" when the road was the best, this time of year.

 

[ken]

Your idea sounds good. But I would think 5/8 hose would over cool the rear cylinders.

 

[Iceman3005]

Since the 2 rear cylinders are the hot spots in the coolant system would it be beneficial to run a rear cylinder head bypass system right in to the heater core input? A few years ago I had read somewhere about the rear cylinder head bypass system and I found the threaded plates that bolt on the heads, they have 1/2 npt threads,then bought a few 1/2 npt to hose 5/8 barb fittings and a few four seasons #84757 coolant y fittings.figured I would plumb into the heater return line,then considered going right to heater core instead. Any ideas, suggestions or thoughts welcome. Thanks.

I was thinking about doing the same thing. The rear cylinders can hit up to 240 degrees while the front one's can be around 190-200. I see there is someone on here selling the coolant bypass kits. I thought about getting the kit, but instead of running it to the front of the engine, have it go to the heater core for better heat.

 

[Drock]

I think you guys are missing one critical point. And that is "better heat" would mean more engine heat over all. I have installed the coolant bypass kit and bin surprisingly pleased with the results. The bypass simply takes away the hot spots thus helping the engine maintain proper, balanced operating temperature. The thermostat dictates the operating temp 190°-195°. If you want more heat in the cabin then the best thing is going to be to keep it there with better insulation. Adding a headliner and insulating under it would make a big difference sense heat rises and all. Followed by under & behind the seats. You might also check and make sure your air box isn't leaking air under the dash and replace the blower motor.

 

[rsh4364]

It's more about taking heat from where you want it the least and routing it to where you would want it the most.

 

[Drock]

It's more about taking heat from where you want it the least and routing it to where you would want it the most.

Yeah but its not going to be any hotter. You MIGHT help the flow problem in the back of the heads but doubtful? and if at all only in the winter. And it would only then be sending 190°-195° coolant to the heater core, as per the thermostat. So still no more heat in the cabin. Our CUCV's have minimal insulation in the cabin. The best solution would be to install the bypass kit, and properly insulate the cabin.

 

[rsh4364]

Hot coolant runs thru heater core summer or winter, there is no shut off valve when it's warm out.

 

[Drock]

Hot coolant runs thru heater core summer or winter, there is no shut off valve when it's warm out.

I understand that. But your not going to be running the heat in the summer. So heat exchange will only happen in the winter.

 

[911joeblow]

Here is a link to detailed information about the flow of coolant in these blocks.

https://paradoxbydesign.com/blogs/news/the-humvee-diesel-engine-cooling-paradox

One of the benefits of these kits is the more rapid heat up of the heater core. We do not recommend running the heater off the rear directly as it will drastically imbalance the cooling flow in the engine.

 

[rsh4364]

Found something different tonight, four seasons # 84908. Would make a DIY rear head bypass easier or give you an extra sensor port.

 

[Big Tom]

I wasn't happy with the coolant heater so I found a 24 volt milliarty inverter . Now the old deuce has electric heat along with coolant heat , warm as toast now!!!

 

[rsh4364]

Yeah but its not going to be any hotter. You MIGHT help the flow problem in the back of the heads but doubtful? and if at all only in the winter. And it would only then be sending 190°-195° coolant to the heater core, as per the thermostat. So still no more heat in the cabin. Our CUCV's have minimal insulation in the cabin. The best solution would be to install the bypass kit, and properly insulate the cabin.

If the coolant temperature at rear cylinders is 190-195 there would be no reason to do the bypass upgrade,the rear cylinders run much higher than the temperature gauge and thermostat on front of the motor.

 

[Drock]

If the coolant temperature at rear cylinders is 190-195 there would be no reason to do the bypass upgrade,the rear cylinders run much higher than the temperature gauge and thermostat on front of the motor.

The coolant at the back of the motor is only A higher temperature because it's trapped. If "theoretically" your heater core trick was able to move this coolant, and balance the cylinder temperatures. Then you'd only be getting the 190°-195° into the heater core. And if it didn't solve the flow problem, and you did get hotter coolant into the heater core. You still have the problem of hotter coolant at the back of the motor. In addition to better cab insulation, you might also want to check and make sure you have the correct heater core. They make 2 versions, one is much thinner then the other and will fit loosely in the air box allowing air to pass around the core versus passing through it.