Truck Overheating and No Cabin Heat

[mjf84]

Been fighting my cooling system for a while now and I’m stumped. 2012 1500, 4.7L V8. 140k miles

Major Symptoms:
-engine overheats after driving it for more than 5-10 minutes
-cabin heat blows cold air
-upper radiator hose is extremely hot, lower hose is room temp, both heater hoses are hot at the engine block and just warm at the firewall/heater core

For context, here’s the treatments I’ve done on the coolant system over the past week:
-new thermostat
-new lower radiator hose
-new coolant temp sensor
-coolant flush + burp air
-pump/hose water/CLR heater core flush
-oil change
-3 years ago new water pump too

Other observations:
-squealing from under the hood when starting cold
-won’t go past 210deg at idle but quickly does when moving
-no visible leaks
-no foamy oil or other head gasket red flags
-AC works fine

Scratching my head at this one. Any thoughts?

 

[mdc1990zr1]

Been fighting my cooling system for a while now and I’m stumped. 2012 1500, 4.7L V8. 140k miles

Major Symptoms:
-engine overheats after driving it for more than 5-10 minutes
-cabin heat blows cold air
-upper radiator hose is extremely hot, lower hose is room temp, both heater hoses are hot at the engine block and just warm at the firewall/heater core

For context, here’s the treatments I’ve done on the coolant system over the past week:
-new thermostat
-new lower radiator hose
-new coolant temp sensor
-coolant flush + burp air
-pump/hose water/CLR heater core flush
-oil change
-3 years ago new water pump too

Other observations:
-squealing from under the hood when starting cold
-won’t go past 210deg at idle but quickly does when moving
-no visible leaks
-no foamy oil or other head gasket red flags
-AC works fine

Scratching my head at this one. Any thought

Been fighting my cooling system for a while now and I’m stumped. 2012 1500, 4.7L V8. 140k miles

Major Symptoms:
-engine overheats after driving it for more than 5-10 minutes
-cabin heat blows cold air
-upper radiator hose is extremely hot, lower hose is room temp, both heater hoses are hot at the engine block and just warm at the firewall/heater core

For context, here’s the treatments I’ve done on the coolant system over the past week:
-new thermostat
-new lower radiator hose
-new coolant temp sensor
-coolant flush + burp air
-pump/hose water/CLR heater core flush
-oil change
-3 years ago new water pump too

Other observations:
-squealing from under the hood when starting cold
-won’t go past 210deg at idle but quickly does when moving
-no visible leaks
-no foamy oil or other head gasket red flags
-AC works fine

Scratching my head at this one. Any thoughts?

I don’t know in what order you may have done stuff but sometimes there are different water pumps that rotate either clockwise or counterclockwise. You may have a pump that fits, but may not be moving water. On a more rare occasion, check to see that the serpentine belt is routed in the proper direction. I had a belt routed incorrectly around an air conditioner pulley that caused a squeal.

 

[04fxdwgi]

Overheating and no cabin heat are sometimes caused by lack of cooling system pressure. You need to be holding 12-15 psi in the coolant system.

 

[Sherman Bird]

Been fighting my cooling system for a while now and I’m stumped. 2012 1500, 4.7L V8. 140k miles

Major Symptoms:
-engine overheats after driving it for more than 5-10 minutes
-cabin heat blows cold air
-upper radiator hose is extremely hot, lower hose is room temp, both heater hoses are hot at the engine block and just warm at the firewall/heater core

For context, here’s the treatments I’ve done on the coolant system over the past week:
-new thermostat
-new lower radiator hose
-new coolant temp sensor
-coolant flush + burp air
-pump/hose water/CLR heater core flush
-oil change
-3 years ago new water pump too

Other observations:
-squealing from under the hood when starting cold
-won’t go past 210deg at idle but quickly does when moving
-no visible leaks
-no foamy oil or other head gasket red flags
-AC works fine

Scratching my head at this one. Any thoughts?

IF your water pump is working properly, and the thermostat is OK, I'll share MY experience with the 4.7L (Mercedes inspired design) engine...
I've dealt with your problem on customers RAM/ Jeeps before. No matter HOW COMPLETELY you THOUGHT you flushed the cooling system, you didn't.
Let me qualify: The very design of that engine lends itself to the proclivity of crud/debris to accumulate in the rear lower corners of the block cooling pockets surrounding the rear cylinders, frequently all the way up to the head gasket level.
The fix which I'VE employed involved knocking out the rearmost "freeze" plugs (more accurately, called core plugs).
I then use my garden hose with a piece of 3/8" steel brake line, bent 90 degrees and adapted to a screw on brass fitting which fits the flange of my garden hose. I then crawl under the jacked up and on jack stands truck and get filthy by turning on a strong stream of water (stream is made strong by orifice effect of the smaller diameter of the brake line. I stick the 90 degree part of the pipe down and back and dislodge the packed crud which defies ALL "flushing" efforts. Believe me, you will wind up looking like you have been stricken with the "Black death fever LOL! And taking a shower becomes a must!

Then, you'll have to isolate the heater core by removing the hoses from the fittings above the thermostat. Take notice of which hose goes where. I use CLR undiluted and pour it into one of the hoses after I affix the ends of the hoses above the heater core level. After filling the core with CLR, I leave it to soak for several hours. Then flush, flush, flush both directions afterwards. I use compressed air with an adapter to force the combo of crud/liquid from the heater core, and WOW! The amount of large particulate is staggering. I once "saved" the cruddy, coffee brown sludge in a clear 1 gallon drinking water bottle to show the customer. But, alas, by the next morning, the CLR had dissolved almost all of it!

These methods worked wonderfully for me, and can help you, too. Good luck.

 

[mjf84]

IF your water pump is working properly, and the thermostat is OK, I'll share MY experience with the 4.7L (Mercedes inspired design) engine...
I've dealt with your problem on customers RAM/ Jeeps before. No matter HOW COMPLETELY you THOUGHT you flushed the cooling system, you didn't.
Let me qualify: The very design of that engine lends itself to the proclivity of crud/debris to accumulate in the rear lower corners of the block cooling pockets surrounding the rear cylinders, frequently all the way up to the head gasket level.
The fix which I'VE employed involved knocking out the rearmost "freeze" plugs (more accurately, called core plugs).
I then use my garden hose with a piece of 3/8" steel brake line, bent 90 degrees and adapted to a screw on brass fitting which fits the flange of my garden hose. I then crawl under the jacked up and on jack stands truck and get filthy by turning on a strong stream of water (stream is made strong by orifice effect of the smaller diameter of the brake line. I stick the 90 degree part of the pipe down and back and dislodge the packed crud which defies ALL "flushing" efforts. Believe me, you will wind up looking like you have been stricken with the "Black death fever LOL! And taking a shower becomes a must!

Then, you'll have to isolate the heater core by removing the hoses from the fittings above the thermostat. Take notice of which hose goes where. I use CLR undiluted and pour it into one of the hoses after I affix the ends of the hoses above the heater core level. After filling the core with CLR, I leave it to soak for several hours. Then flush, flush, flush both directions afterwards. I use compressed air with an adapter to force the combo of crud/liquid from the heater core, and WOW! The amount of large particulate is staggering. I once "saved" the cruddy, coffee brown sludge in a clear 1 gallon drinking water bottle to show the customer. But, alas, by the next morning, the CLR had dissolved almost all of it!

These methods worked wonderfully for me, and can help you, too. Good luck.

Feel like this may be normal, not sure. When I remove both heater hoses from the engine block, the attachment for the bottom hose sprays coolant. So I can’t really keep both hoses disconnected- any idea what to do?

 

[Hambodian]

I had a similar situation on a Ram 50. Super hot upper hose, cool lower, and heat comes and goes. I re-torqued my head bolts and it solved it. I didn't have any oil/coolant mixes or leaks, so It was odd. I had previously replaced the head gasket and I guess it got loose just a tiny bit. Might not be your issue, but maybe worth a check if it's accessible.

 

[Sherman Bird]

I had a similar situation on a Ram 50. Super hot upper hose, cool lower, and heat comes and goes. I re-torqued my head bolts and it solved it. I didn't have any oil/coolant mixes or leaks, so It was odd. I had previously replaced the head gasket and I guess it got loose just a tiny bit. Might not be your issue, but maybe worth a check if it's accessible.

That was a Mitsubishi engine...

 

[Hambodian]

That was a Mitsubishi engine...

Yes, it's pretty much a Mighty Max. Awesome truck. But I'm just saying that the head gasket might still be worth a look even though the indicators don't point to a bad gasket.

 

[jawzs2]

My money's on a clogged radiator and heater core. Are you the original owner? A clogged heater core is fairly common on these, radiators not so much but often enough. If the wrong type of coolant was ever used, the different types don't mix well together and turn into a gel.

 

[Sherman Bird]

Yes, it's pretty much a Mighty Max. Awesome truck. But I'm just saying that the head gasket might still be worth a look even though the indicators don't point to a bad gasket.

Either you have the 2.6L or 2.0L 4 cylinder. Those will crack the cylinder heads. They are not too bad to R&R the head, but a good machine shop needs to do a vacuum leak and dye test.

 

[Burla]

RMI 25

The best part of RMI 25 is you will know if there are any clogs or gunk in any line it touches, it takes all contamination and deposits or traps it in Overflow and then you wet vac it out. If your over flow is clean at 500 miles, so is your lines. They should call this stuff radiator shops secret, the stuff is unbelievable.