I am new to my '01 Ram Sport 5.9L and the forum, but since temps in Wisconsin these days are flirting with a negative symbol in front of them I have really noticed a lack of good heat on my morning comute.

I have noticed that the heat/air temp is luke warm at best while idle or at highway cruising RPM, but if I give her some gas and get her turning 2500 and higher RPM the air gets much warmer.

Water pump was replaced by previous owner, and it is nice and clean so I tend to believe that. he said the T-stat was replaced too but my temp gauge shows about 170 deg running temp, I dont know if my sending unit is bad or if that is just how cool I really am running in which case I would say the T-stat is bad. Also checked coolant levels and the rad is topped off and overflow has coolant in it as well.

To me this is all starting to point to a low flowing/plugged heater core, do these symptoms sound familiar to anyone else here and if so what were some of the solutions?

 

May also be air still trapped in the heater core. These trucks are notoriously fun to get all the air out....... could try burping the system again.

You are running to cold. Are you getting any codes? Got a scanner you can plug in to see what temp the PCM thinks then engine is?? (might just be the gauge lying to you....)

 

No codes at all...I will try burping it again later on tonight after work. Unfortunatly I don't have a scanner. I may also spend the $15 for a new T-stat since that is fairly cheap and easy to replace.

 

No codes makes me wonder if the gauge isn't the culprit here. Usually, running that cold would set a code.... (engine too cold too long.)

Most auto parts stores have scanners that can read codes and such, call around, and see if one of them can read data, cruise it up there, and with engine at operating temp, see what the scanner says.

 

If the gauge is bad that is fine I can deal with that, it would not be the cause of my poor heat.

After looking at the DIY for the heater core I am crossing my fingers that there is just some air left in there. Any tips for getting the air out of these?

 

I backflushed mine.... then ran water thru it in both directions till it ran clean. Burped the cooling system in all sorts of strange ways, and I STILL only get luke warm heat....... So, I am fresh outa ideas here.

 

I see that Hypertech has a 160 deg T-stat for the 5.9L like they do for most other vehicles. Now I know that does not mean the engine will run at exactly 160 but that would run somewhere aroud 175 to 185 where my gauge is sitting. That being said if my T-stat were say stuck open slightly that may be the reason for the low reading on the gauge and the less than ideal heat from the vents. I don't think that 160 deg T-stat would trigger a code but I could be wrong on that.

 

160 would certainly trigger a code. Even the 180 does for some folks.

 

I have the 180* and i get the code in southern Indiana as soon as temps get "down" to 45 degrees.

Heat has been good, but if it were negative, I would not have very much heat running a 180* stat. I know that for a fact. Maybe the PO of your truck put a 180* stat in there.


I used to complain that my 1996 5.2 ran at 210* and if temps were 95 degrees and over, it would get pretty hot. Towing, it ran very hot, which meant NO AC!!! Didn;t like that at all.

However, my truck never gets over 200 if the temps are 108 (Lived in Arkansas and running full AC on the hottest of days never got me worried).

So it is a love hate relationship. I am guessing 1. air in system, 2. the thermostat. If the gauge was wrong, you would still have heat.

 

I run a 180 stat also... but no codes in buffalo winters here in the three years on this stat. heat is fine so far but I dont drive it much since somethings always broke..... right now I have a head / valve related misfire to deal with.. I'm sure now that I mention the heat working it will go south on me too...