I get awsome heat out of my truck, after i put a new heater core in that is. It wasn't bad before i changed it, but it had a good leak. I put one aftermarket heater core in once in truck just like mine, and it wouldn't put out any heat after i changed it tryed bleedin it everthing, even hooked up a hot water hose to it and i could only get the slightest bit of heat out of it. So i put a heater core from dodge in it, and it worked perfect. I put hot water thought the aftermarket heater core once it was out and only the top part got really hot, seamed to me like the top tank part of it was just bypassing the fined part. If your cooling system was full of rust you may need to run a chemical cooling system flush though it then pull a heater hose and run hot water into it while the engine is hot and running, the water from the tap will fill the system as fast as the engine dumps it out. this way seams to work well you can flush it till the water comeing out is perfectly clean. Backflushing the heater core can help if its plugged, but i've had them so bad that that didn't fix them had to replace them.

 

hey hey, well my truck isnt overheating anymore but I am having the same problem,even with my cummins t stat. BTW, Thanks for the use of the rad cap and all the help rob.

Edit: i have good heat, I just have the dancing temp gauge.

 

Once I get the updated T-stat,3802968..Will see what that does.

 

hey dave ,
when the truck had good heat , were you just running diesel ?

 

Yes..it was diesel..But have run a higher mix since then...I could see what your thinking...

 

Ignore this post....that part number will not fit....I have another T-stat coming in that has a slow opening speed...What a pain...

 

Just wondering if you ever found out the problem? My truck's heater isn't working as good as it should either. I put a warmer thermostat in to see if that will help now the temp is jumping ~10 degrees. I am going to try and bleed the line to see if I got any air in there. Do you just crack the heater lines till coolant comes out to get all the air out? Any other idea's?

 

My head has a 1/2"? plug on top by the tstat. That may be a good spot to bleed air as i could see it getting locked there. also you could do a little fillin from right at that plug which might help with the airlocking.

 

Paying Cummins or Dodge $50.00 for the annointed thermostat is no guarantee the thermostat is any better quality than the aftermarket brands.

I was under the illusion Cummins wouldn't sell you crappy parts -- WRONG!

Taking the $50.00 thermostat out of the box my mechanic friend spotted it right away; "that's a junk stat, you ain't going to like it".

He was right, the temp gauge varied by 40 degrees, I hated that stupid stat.
My old 92 CTD was steady needle for 300K miles.

The mechanic friend gave me an invaluable tip.
"Always search out a Robertshaw design thermostat".

----------------------------------------------

Robertshaw-Design Thermostat

The thermostat may carry trade name identification as “Robertshaw”, “Stant”,
“Purolator”, “Prestone”, or “Atlas”.

No matter which “brand name” may be associated with this part, it was originally produced by Robertshaw Controls and is now manufactured for Cooper Standard, a major supplier to the automotive industry.

Catalog link

Prestone part number for the Dodge Cummins is 727-180
Stant part number 14248
Napa part number 370-180 (Make sure there is Robertshaw design in Napa's box)



.

 

I went through two differnet cummins T-stats...Two different p/n and temp ratings...I hated both of them.Went to Napa and got one of there heavy duty t-stat for $20 less and it work way better than the cummins ones I purchased.I removed my fan and placed a copy sheets of cardboard in front of the rad.Works alot better now....Still not perfect but the truck warms up better and the temp gauge doesn't swing back and forth as bad as the cummins t-stat.

 

my truck is making pathetic heat as well, always chilly inside even if its only 10 below out and youve been working it for an hour. I dont know if i got air in the core when i did my motor as i never had to use the heater before. the lines are both hot to the touch, the hose of the head is noticably warmer then the return line. Whether this is due to a lack of flow or the heater core actually pulling some of the heat off i dont know. Can you guys feel a difference between the two hoses?

 

Yeah my heat is horrible from what it was last year. I might swap out the heater core tomorrow if I can find one.

 

My '92 and '01 CTDs were both bad for cab heat even though the engine temps gauges were coming up to normal. My sister's '01 gasser on the other hand has always put out good heat.

My '03 puts out great heat, this is till the fan quit two days ago.....

 

I had marginal/OK heat heading up northwest of Peace River last week in the 01,card board in front of the rad,comfortable for me but if the MRS was with me i could hear it now.It was in the -30C or colder so a winter front would have been better,the hottest my aftermarket water temp gauge reached was 180 at the port on #6,the temp gauge on the NV5600 tranny did not even move off of 100F---so airflow under the truck plays in because on a regular summer day it reaches 160F.Also lost a bit of fuel pressure in the cold---Airdog usually run at a constant 14PSI but i was running around 12PSI--cold was effecting it but i ran a ton of additive.On the way back at -15 or so had plenty of heat,actually turned it down to low.DW

 

If your concered about trans temp or just cold air flowing under the cab, get a canvas tarp, princess auto sells them at a decent price and wrap it from the top of the rad, under the front axil and back as far as it reaches, don't bother going farther than the back of the cab. IT will help with heat a lot. I havn't tarped up my 01, but i did my 98 gas job becuase the trans would run cold and the computer wouldn't let it go into overdrive. The belly tarp worked. I used mechanics wire to strap it up, made sure it wasn't too tight where the steering linkage was and it held in place all winter. Trans was warm enough to shift into over drive, I didn't have any gauges so I don't know the exact temp diff.