[wolfram]

A month ago, I replaced the radiator, water pump, and thermostat on my 98 Ram 5.9 Auto 4X4. A week later, I tried to use the heat and found I basically have none. I was getting barely warm heat from the vents.

I assumed the heater core was clogged, but both the supply and return hoses were equally hot. I then assumed I had a blend door issue. I removed the glovebox and found the temp control was operating normally.

Today, I replaced the starter and noticed that the overflow tank was quite low. I refilled and checked the radiator level, which was normal. I put the truck up on ramps in the front and ran the engine up to temp with the cap off the radiator. I noticed that I had decent heat like that.

I put the cap back on and drove the truck only to find that the temp from the vents went down. I still had more heat than before I started, but not nearly normal. I also found that I now get normal heat from the vents when the throttle is wide open.

The temp gauge only gets to halfway between the second line of the gauge (the one to the right of the line that reads "130") and the middle line, which reads "210". I can't remember where the gauge used to read. Could I have gotten a bad t stat or maybe I should have replaced the radiator cap?

Any and all help is welcome, and don't assume I know anything, because I pretty much don't....

 

[tnau664]

Start with the stat

Start with the stat. You can get bad ones right off the shelf and make sure you use the recommended temp.

T'nau :gr_patrio

 

[dhvaughan]

i'm also guessing bad t-stat. you might want to put in a 195 degree for winter time, and maybe/maybe not put in a 180 in summer. (careful, some people get a check engine light with a 180). your temp gauge should be up fairly close to the center (210) line with a 195.

another thing you can do is to backflush your heater core both ways and make sure you've got good flow through it.

 

[wolfram]

Thanks for the replies.

 

[brandonh420]

I have the same problem. I don't think it is the stat. My temp was in the same place as before I changed the stat. I also have changed the core and the water pump. I think they were all good. My heat is also fine when you bring up the rpm's. I have been racking my brain but I also don't know what else is in the system but for some reason fluid flow is being impeded. That would be the only reason for it to gain heat with rpm. Temp does not change. I hope someone can help us with this. It is driving me nuts.

 

[wolfram]

Thanks everyone for the replies. I finally got a chance to flush the core and a very small amount of discolored crap came out. It was enough. I now have outstanding heat!