Warmer heat

[Whitaker717]

Hey guys, I just got my heater core replaced and while the heat gets warm I would think it should cook me out of that little truck. Is there anyway to get warmer air in these things? Everything is new. New radiator, evap coil, water pump, thermostat(I’m guessing 180 but idk). Thanks in advance. 87, 4.0

[gogmorgo]

Putting in a stock 195 thermostat will bring your heater temperature up quite a bit. Around here I’ve even known people to put in a 205 for even more heat, although I think that’s overkill. Even at -40 I’ve rarely ever had my temp slider much past half, maybe 3/4 at the most. I don’t do the old-man trick of blocking the radiator either.
 

Other basic maintenance stuff like making sure the coolant is topped up will help. It’s also worth making sure the blend door is operating correctly, opening all the way. Also that the heater valve is working.

[Whitaker717]

2 hours ago, gogmorgo said:

Putting in a stock 195 thermostat will bring your heater temperature up quite a bit. Around here I’ve even known people to put in a 205 for even more heat, although I think that’s overkill. Even at -40 I’ve rarely ever had my temp slider much past half, maybe 3/4 at the most. I don’t do the old-man trick of blocking the radiator either.
 

Other basic maintenance stuff like making sure the coolant is topped up will help. It’s also worth making sure the blend door is operating correctly, opening all the way. Also that the heater valve is working.

Is there a certain type of coolant to add and how much? 

[pizzaman09]

Might you check to see if all the lines are plumbed to the correct spots under the hood and that your vacuum operated heater valve is working under the hood.

[Whitaker717]

2 hours ago, pizzaman09 said:

Might you check to see if all the lines are plumbed to the correct spots under the hood and that your vacuum operated heater valve is working under the hood.

Is there a way to test that valve? It blows pretty warm air but I think it should be hotter. 

[pizzaman09]

45 minutes ago, Whitaker717 said:

Is there a way to test that valve? It blows pretty warm air but I think it should be hotter. 

It is a simple vacuum operated valve, I'm not certain which way is open, but you should be able to unplug the vacuum line and rotate the valve from the lever arm to open it up.  

[Whitaker717]

Just now, pizzaman09 said:

It is a simple vacuum operated valve, I'm not certain which way is open, but you should be able to unplug the vacuum line and rotate the valve from the lever arm to open it up.  

Interesting. I will check it out. Thanks

[Whitaker717]

46 minutes ago, pizzaman09 said:

It is a simple vacuum operated valve, I'm not certain which way is open, but you should be able to unplug the vacuum line and rotate the valve from the lever arm to open it up.  

I checked that out and it holds vacuum. There is a lever underneath it you can push in. 

[gogmorgo]

6 hours ago, Whitaker717 said:

Is there a certain type of coolant to add and how much? 

Not really. Any 50/50 blend of the old fashioned toxic green ethylene glycol coolant will do the job. The universal premix is okay if you don’t want to mix it yourself.

I personally will buy name brand concentrated coolant for better anticorrosion and wear properties, and spend money on deionized water, again for corrosion, and mix it roughly 2:1, to give myself extra low-temperature performance. It’s a little overkill even for around here but mixing it rich like that will give me a little extra freeze resistance, but at the cost of reduced heat capacity, which has been noticeable in warmer weather. 

Running deionized water is probably overkill as well. Distilled would be fine. Honestly even tap water if it’s reasonably soft. I won’t lie and pretend I’ve never topped up with river water strained through a t-shirt in a pinch, flushed and replaced at earliest opportunity of course. But I started running deionized when I had a steady free supply of it and when I changed my ZJ’s original water pump at 200,000 miles it still looked brand new. Even the inside of the block was shiney bare-metal clean. I was only changing it because the bearing was shot. So I figured I should keep doing what I had been doing. 

[Whitaker717]

1 minute ago, gogmorgo said:

Not really. Any 50/50 blend of the old fashioned toxic green ethylene glycol coolant will do the job. The universal premix is okay if you don’t want to mix it yourself.

I personally will buy name brand concentrated coolant for better anticorrosion and wear properties, and spend money on deionized water, again for corrosion, and mix it roughly 2:1, to give myself extra low-temperature performance. It’s a little overkill even for around here but mixing it rich like that will give me a little extra freeze resistance, but at the cost of reduced heat capacity, which has been noticeable in warmer weather. 

Running deionized water is probably overkill as well. Distilled would be fine. Honestly even tap water if it’s reasonably soft. I won’t lie and pretend I’ve never topped up with river water strained through a t-shirt in a pinch, flushed and replaced at earliest opportunity of course. But I started running deionized when I had a steady free supply of it and when I changed my ZJ’s original water pump at 200,000 miles it still looked brand new. Even the inside of the block was shiney bare-metal clean. I was only changing it because the bearing was shot. So I figured I should keep doing what I had been doing. 

Thanks for the info! I can just see a max line in my bottle. 

[gogmorgo]

46 minutes ago, Whitaker717 said:

Thanks for the info! I can just see a max line in my bottle. 

If you’re still running the closed system that’s probably fine. Keep an eye on it just to make sure it stays full, in case there’s any air in the system that works it’s way through. 

If you’ve had an open conversion make sure the pressurized side is still full. It’s possible to have a small leak you’d overlook and have the level drop in the system without changing the level in the overflow. It could push pressure out the leak and then suck air back in instead, and you’d never know just looking at the overflow. 

[Whitaker717]

Just now, gogmorgo said:

If you’re still running the closed system that’s probably fine. Keep an eye on it just to make sure it stays full, in case there’s any air in the system that works it’s way through. 

If you’ve had an open conversion make sure the pressurized side is still full. It’s possible to have a small leak you’d overlook and have the level drop in the system without changing the level in the overflow. It could push pressure out the leak and then suck air back in instead, and you’d never know just looking at the overflow. 

I still have the closed system and there is only about 1/2” filled in the bottle. I’m about 2 or 3” below max line

[cruiser54]

I use ONLY Mopar thermostats. a little pricey but they warm the engine very quickly and the temp is stable at running temp. 

 

I live in the mountains of Arizona where temps can vary from 0* to 100* F. 

[saveevryjp1998]

 You should be getting cooked out in an MJ. I'd verify you have proper vacuum operation at the heater control valve 1st if your not getting a boil over and 100% sure your coolant system is purged of any trapped air. When you purged the system did you eventually work your heat on high to cycle the new core and repeat fill/purge process? If not I'd bet money there is still air trapped in the system. I've learned initially that there is kinda a sweet cool weather temp range in Indiana that an improperly purged closed 4.0 coolant system will easily go unnoticed. Especially the colder it gets with wind-chill. Just because it's not reaching critical boil over fast, doesn't mean there isn't air. It's weird since it almost more acts like what your describing as running cool. It's because it's not sensing proper coolant temperature. Air and coolant will change temperature at different rates,  Giving uneven readings. So air still in the system can do it, simply could be your heater control vacuum isn't opening up when you turn it on in the cab. Those lines like to dry rot up this way. I'm guessing mostly due to years of neglected hot coolant boil over. Sometimes mice or something chews/cuts them on the inside of cab. Maybe since you replaced everything, obviously it was apart, something may have happened during install. Have you pull the temperature control inside the cab? Checking everything there? I'd test the obvious that doesn't cost anything.