2nd Gen Non-Engine/Transmission no heat

[SeanM]

I know what your saying srath but I didn't have this problem last winter when I lived in maine. Now I live in Mass (the armpit of the world) so I know there is most certainly somthing wrong. The last few days have been really cold granted, its normally around 20-30 but even at that temp its still hard for me to get heat. Plus if Mikes readings are correct then mine are way low. I am going to check the water pump and t-stat tomorrow and see if either of those two are the culprit.



Also, manual says that the heat coming from the floor ducts with the blower motor on high should be no more then 40 degrees less then engine temp. It also list the water pump as a possible cause.

 

[SRath]

You did not answer whether you have your radiator blocked off or not, but you have been posting abnormally low temp readings from the hoses coming from your engine, so I'm guessing not. If not, there's your problem.



If the t-stat is closed, your coolant is not flowing. If your coolant is not flowing, the coolant in your heater core stays there and is also cooled by your blower fan. Thus: no heat. The only way you will have constant hot coolant flow to your heater core is if the engine is operating at the proper temperature and the t-stat is open. Clearly, the upshot of everything you have tried and tested comes down to a lack of hot coolant flow through your heater core. That would be why. You have no coolant flow because your t-stat seldom opens because your engine seldom gets warm enough. Operating your engine below 180* isn't good for your engine, either.



The cooling systems on these trucks is a highly effective monster and is actually too much in sub-zero weather. Just slip a piece of cardboard down between your radiator and intercooler and see if it makes a difference for you. You can always cut small openings or flaps like I do, to adjust airflow. It's a zero-cost, low-labor thing to try. You have a temp gauge, so you are in no danger of cooking your engine.



Even with a big snowplow blocking the wind and a plastic slip-sheet blocking mine, I can drive highway speeds with only a small 6 inch square opening in the plastic and my engine temp is perfect and my heater output is awesome. And, yes, we have been having temps down to -22 actual (not the windchill) here, too, recently. I think it's -9 and falling right now.

 

[Hammer]

Sean. .

If your in Mass no why not try and call Scott Hovey at MassDiesel and see what ideas,if any. he may have. He has been slinging wrenches on these trucks for years and probably has seen it all and may be able to help... ... . Andy



massachusetts diesel performance repair shop

 

[mwilson]

The coolant flows in the block with the thermostat closed, just not thru the radiator.

It has to.

The water pump is turning and circulating coolant, the thermostats job is to hold the water in the block until the set temp is reached, then it opens at 180 degrees and allows coolant to flow thru the radiator. Even if the block is only 100 degrees then 100 degree water, not 70 or 80 degree water should be flowing into the heater core.



Blocking the radiator will help keep the thermostat open and keep the engine closer to the desired 180 degree temperature as there is less heat loss due to reduced air flow thru the radiator but that does not address Shawn's problem.



There are two reasons that I can come up with, a plugged heater core which he has already ruled out, or a lazy water pump.



With my thermostat open or closed I am getting block temp to the heater core. That is what should be happening.



Mike.

 

[SeanM]

The plot thickens... ..... The water pump is perfect. So now that that is eliminated I am back to where I started. FREEZING

 

[SeanM]

I'm going to replace the t-stat is fairly cheap and the only thing I keep questioning in my mind. I have seen t-stats do some weird things before.

 

[mwilson]

Can't get the impeller to slip on the shaft at all?????



I was really hoping you could spin the impeller by hand, but that theory is blown.



Maybe the rubber seal ring on the thermostat is out of place.



Are you anywhere near Cummins Northeast in Dedham so you can grab an OEM thermostat??



Let me know if not, tell me what town you are in and I will try to help you locate one at a truck dealer, equipment dealer or something nearby.



Call me if needed... ... . 800-432-7936 Ext. 121



Mike.

 

[SRath]

This is ridiculous. You keep looking for a problem with the cooling system when the problem is actually a cooling system that is working too well.



Why does your engine even have a thermostat?



> because even under normal design ambient temperatures, which are well above zero, the cooling system is capable of preventing the engine from reaching an appropriate operating temperature of 180*. That t-stat is not part of the "cooling system" as much as it is a part of the "heating system". It's job is not to aid cooling; it is to aid warming.



The cooling system was designed to handle its duties on hot days under heavy loads. Even on a hot July day, my temp gauge climbs slowly to 180*, then the t-stat opens, the radiator dumps cold 100 or so degree coolant into the pump & block, and the needle drops like a rock to 130* and begins a slow climb back to 180*. It repeats this cycle endlessly.



Now imagine the coolant in the radiator is at sub-zero temps. Your engine is struggling to even reach 180*. If and when it ever does, that sub-zero coolant (it would be a solid block of ice if it were 100% water) is dumped into it and the engine temp instantly plummets. It takes a very long time to heat that coolant (block of ice) up to 180* again. You only reached "operating temperature", 180* for a brief moment during all of this. Most of the time was spent well below that. That same too-cold coolant is being cooled even more by your mini-radiator -- your heater core.



You keep describing a cooling system that is working too well. You take temperature readings well below the designed operating temperature of the engine. You complain of no heat.



Yet you refuse to help your t-stat do it's job of maintaining an acceptable operating temperature by restricting the arctic cold air causing the arctic cold coolant that it is trying to heat up.



That's like complaining about being cold when you have all the windows and doors on your house open, and then blaming a furnace that is functioning perfectly but being overwhelmed.



Restrict your radiator airflow when it is sub-zero or learn to enjoy being cold. It really is that simple. Do you think truck drivers put on winter fronts (airflow restrictors) because they look cool?

 

[mwilson]

This is ridiculous. You keep looking for a problem with the cooling system when the problem is actually a cooling system that is working too well.



Why does your engine even have a thermostat?



> because even under normal design ambient temperatures, which are well above zero, the cooling system is capable of preventing the engine from reaching an appropriate operating temperature of 180*. That t-stat is not part of the "cooling system" as much as it is a part of the "heating system". It's job is not to aid cooling; it is to aid warming.



The cooling system was designed to handle its duties on hot days under heavy loads. Even on a hot July day, my temp gauge climbs slowly to 180*, then the t-stat opens, the radiator dumps cold 100 or so degree coolant into the pump & block, and the needle drops like a rock to 130* and begins a slow climb back to 180*. It repeats this cycle endlessly.



Now imagine the coolant in the radiator is at sub-zero temps. Your engine is struggling to even reach 180*. If and when it ever does, that sub-zero coolant (it would be a solid block of ice if it were 100% water) is dumped into it and the engine temp instantly plummets. It takes a very long time to heat that coolant (block of ice) up to 180* again. You only reached "operating temperature", 180* for a brief moment during all of this. Most of the time was spent well below that. That same too-cold coolant is being cooled even more by your mini-radiator -- your heater core.



You keep describing a cooling system that is working too well. You take temperature readings well below the designed operating temperature of the engine. You complain of no heat.



Yet you refuse to help your t-stat do it's job of maintaining an acceptable operating temperature by restricting the arctic cold air causing the arctic cold coolant that it is trying to heat up.



That's like complaining about being cold when you have all the windows and doors on your house open, and then blaming a furnace that is functioning perfectly but being overwhelmed.



Restrict your radiator airflow when it is sub-zero or learn to enjoy being cold. It really is that simple. Do you think truck drivers put on winter fronts (airflow restrictors) because they look cool?

That is correct but if that thermostat is closed you could theoretically remove the radiator and toss in the back of the truck. The block is on it's own until the thermostat opens to allow flow.



My interest in Sean's problem is his 20 degree loss of temperature at the inbound heater line versus the block temp. There is a problem there somewhere.



The cardboard will help keep things warm once the thermostat opens and stop a little air blowing by the block when the thermostat is closed but is quickly overcome by the arctic air coming in from underneath the truck.



Winterfronts used to be important back when trucks had direct drive fans, no argument there, but nowadays with hotter thermostats and clutch fans we don't even stock them anymore here.

Shouldn't use them with a charge air cooler anyways.



-17 below this morning, had good heat after driving 5 miles or so, thermostat started to cycle after 10 minutes on I-95 at 75mph. No cardboard or other blocking material on my truck.



Sean's is capable of the same thing if everything is working as it should.



Mike.

 

[SeanM]

Srath,

I blocked the radiator with a piece of cardboard I cut out to fit perfect between my radiator and intercooler just to see. It did help my truck warm up considerably quicker and keep the t stat open while the truck was idleing at a redlight however, it did nothing to help my cab heat. My problem isn't getting my engine up to operating temp its getting heat to the cab. I run a 190 going down the interstate and just barely under 190 running around town. Also, about a week and a half ago I drove for 60 miles on I-90 WITH my 30' G-neck and a old allis chalmers wc farm tractor on it. I think the tractor weighed 3k and my trailer weighs 4,500 lbs. So with 7500lbs behind my truck the engine should have been more then warm and I still didn't have any heat.



Mike,

I'm at a loss. I tried as hard a I could (by hand of course) to turn the impeller on the shaft but it was good. I was also hoping it was the water pump but my gut is pointing me to the t stat. At this point its the cheapest thing to replace. I just don't understand how I can watch the the temp guage move as the thermostat cycles. But I also can't explain why my heater hose is so much cooler then the block temp.



I called cummins northeast down here by me and they wanted $76 for a thermostat! I could swear that I only paid $34 for the one thats in there now and thats a cummins oem part. I am going to keep looking for one tomorrow. Let me know if you have any other ideas.

 

[SeanM]

I just had an idea...

I know where there is another truck just like mine. I am going stop and see if they will let me use their truck as the control. I will get them both warmed up and then take readings with my thermometer on both trucks. Maybe that will help me track down where my problem is. That will also determine if maybe my Ir thermometer is off. I I have heard of IR thermometers being off as much a 20-30 degrees.

 

[GAmes]

I might have missed it, but I did not see where you opened up the plenum and checked for debris blocking the flow of air over the heater core. I am hoping you find the cause for no heat, but I can't think of anything else besides the thermostat. I don't believe that is the problem, however, because you are able to get 190 engine heat. I haven't been to the great white north this winter, but in winters past I have never had a heat problem and have never blocked the radiator. Every spring I remove the fan and spray a cleaner over the heater core, let it sit awhile, then rinse it off with low pressure, low flow water. The water drains from the A/C drain.



Perhaps you could remove the fan and just blow low pressure air through the core. If you get a lot of dust, hair, leaves or whatever out of the intake then that may be the problem.

 

[SeanM]

I had couple people PM me wanting to know what happened with the truck so... ...

I plugged a space heater into my convertor and have had great heat lol anyways we will know tomorrow. I have not had a chance between my 2 month old, work, part time work, and helping my dad and grandfather. I have the whole weekend to myself so tomorrow I will let you guys know what I find. I did have to buy a new blend door actuator but that was because I lost my temper not what was causing my problem. My little temper tantrum only cost me $146. One way or the other it will be fixed tomorrow.

 

[mwilson]

Any luck Sean?????

R U Warm yet???



Mike.

 

[SeanM]

I'm warm with my space heater on. Friday night my son got sick so I was up with him all night, literally. Sunday I had to help my dad get rid of some snow and help hook up the loader on his tractor. I figure at this rate I should get it fixed by july.

 

[SeanM]

I finally did it!!!!!!!!! and unfortunally my heat still sucks. Too make a very long story short. I replaced all of the weatherstripping inside the hvac housing, the evaporater, blower motor and the blend door actuator. I pretty much restored the HVAC housing to new. My evaporator was clogged pretty good and by the looks of it I am guessing that may have been my leak in the a/c system for all these years which is why I replaced it.

If you payed attention you notice I did not replace the heater core. The reason is because the old heater core was made of coppper while the new on is made of aluminum. Well we all know copper holds heat better then aluminum so I compared the flow between the two them and they were identical so there is nothing wrong with my heater core. That outside of the heater core was near perfect also so I put the old one back in for now. My heat improved to 115 at the floor ducts with the blower on high. Its now bearable to drive the truck in the cold atleast but still not where it needs to be.

Anyways it took me about 1 hour 20mins to remove the dash and HVAC housing, 3 hours to disassemble the HVAC housing and replace all the weather stripping, related parts and reassemble it. And about a 1 hour to reinstall everything back in. All in all not to bad.

By the way, if someone feels the need to tell me I'm wrong for reinstalling the old heater core just shut up because I don't want to hear it, there was nothing wrong with the old one and there was no point in replacing it with a inferior part.

 

[airbus320]

The heater core that I got from the Dodge dealer was copper and also make in the USA.

 

[Cliffman]

I'm having the same problem. I flushed with hot water mixed with radiator flush and used a pump to push it through. Seemed to help for a while but its back to low heat again

 

[nauidvr1]

I'm having the same problem going on two winters now. In the last 2 weeks I have done everything mentioned in this thread. I have flushed the system several times, flushed the heater core, used Prestone Super Flush and drove truck with flush chemical in system for 10 hours. I have flushed the system so many times, I know its clean. Changed the thermostat. I have even used a clear discharge hose to inspect all fluid flushes as they were coming out of radiator. I have captured over 60 gallons of my flush water and all of it is clean as a whistle! I have replaced all my air box doors (Re-Circ, Mode 1, Mode 2 & Blend Doors) with the metal ones made by Heater Treater dot net.

I'm at my wits end and I'm literally freezing in my cab!

 

[Nyoest]

I had a similar issue last winter. I have a thirty minute commute and the heater was in high the entire time and when wearing a winter coat it was tolerable. New water pump, new t stat from cummins and blocked radiator were no help. I bored holes in the hvac housing and stuck a bore scope in to inspect. No debris or blockage either. A good blow out through the holes and and some black caps from the hardware store I was back to zero. Only thing left was the heater core.



The reason the inbound temps are low is the heater core is partially blocked internally and not letting all the hot water in. The water pump creates flow, not pressure. My core was full of calcium. Just like a water heater on hard water, damn ol calcium. No one ever uses soft/distilled water for coolant when they should!



My solution was to remove the heater core lines, blow out all coolant and fill one heater core line with calcium cleaner until it flowed out the other line. I let t work for fifteen minutes and then rinsed with water. I caught the water in a pan and it looked like it was full of kidney stones! I reapplied the cleaner and rinsed two more times. I now have adequate heat and all it cost was about $15 and an evening.



And yes, you should have most defiantly changed the core while it was out. We did the wife's 01 heater core and I'm not ready for that again.