Cant get any heat out of my 98 Ram 1500

[Tilar]

I've replaced the thermostat twice thinking maybe I got a bad one. The temp gauge is running roughly 170... I say roughly because it doesn't have numbers between 130 and 210. When it is sitting there idling or I am going slow in town it seems to get plenty of heat out of the heater, but once I get on the road it cools down to the point that it's just tolerable, nothing to brag about. The antifreeze looks really clean and so does the inside of the radiator. When it is putting out heat I can move the temp control and it does affect how hot it is so I'm guessing whatever the temp control moves is working...

Any suggestions? It has close to 180k miles on it.

[JB400]

I have the same truck, and get more heat out of it using the defrost than I do the heater itself.

[ACUDANUT]

 Well it's getting old. You know more things are going to quit or go bad.  I'd trade it in and get a new Christmas truck. 

[rt green]

try flushing the heater  core

[ACUDANUT]

Chances are he will need a new one.

[Ghoste]

And NOT a fun replacement in those.

[jaak]

I am not sure if Rams had the same problems as Dakotas around the same model (my Dak is a 97), but it is a common problem in Dakotas to have no heat. The issue was with the heater core, the passage ways of the factory heater core were small and somewhat restrictive and doesn't take much to clog them up. The new ones you buy now are redesigned and actually shape differently, it comes with instructions because you have to make a couple of minor modifications to the heater core housing. You may want to try back flushing your heater core first, (I tried mine in my Dakota, and the heat worked... for about a day), if that doesn't help I would say replace the heater core.

Like others have said, it's a job, but if your handy with tools It can be done in a few hours. On my Dakota, you pretty much have to remove the entire dash, then unbolt the heater box for the firewall, then disassemble the heater box to replace the core. If you can do it yourself, by the time I bought the heater core, antifreeze, and a couple of other small things, I spent about 50 bucks.... best 50 bucks I spent on that thing... no more frosted balls.

Jason

[Tilar]

Damn, that doesn't sound like fun... I'll try to back flush the heater core tomorrow, A friend of mine suggested doing that shortly after I posted this.

[Patronus]

Sometimes radiators work too well when it's cold out. Why don't you take some cardboard and cover part of the grill?

[Charger RT]

if you flush it. try hooking two short hoses to the heater core so you can fill it with CLR and let it soak a while then reverse flush it. when you reinstall the heater hoses reverse there position if they reach.
Tim

[Tilar]

if you flush it. try hooking two short hoses to the heater core so you can fill it with CLR and let it soak a while then reverse flush it. when you reinstall the heater hoses reverse there position if they reach.
Tim

hmm, Not a bad suggestion, I'll get a bottle of that. The hoses are way different lengths but I might be able to get close enough where they hook at the firewall.

Sometimes radiators work too well when it's cold out. Why don't you take some cardboard and cover part of the grill?

I have cardboard covering probably 2/3 or so of the radiator already and it never runs hot on the gauge.

[Stretch]

Replace the heater core. It can be done in about 2 to 3 hrs. You don't need to disconnect the ac in those. You can work around it. Drop the steering column down. Pull the kick panels. Loosen the 13mm head bolt (1 on each side). Remove the air bag module cover and mount on the center hump. Disconnect the hoses and remove the ECM and under the hood. Remove the 4 (if i remember correctly)12mm nuts. 2 behind the ECM bracket. 2 on fire wall behind engine. Go back inside and remove the screws across the top of dash. Tilt dash down and pull right side back (it will pivot on the lower bolts you loosen. the dash frame is slotted so it will lift off the loosed bolt). Remove 2 bracket screws from heater tubes. Remove 10mm nuts that hold HVAC box and pull back a few inches. Cut heater core tubs and lift out. New aftermarket core will have movable tubes. (moveable tubes make it possible to install without messing with the AC. Reassemble and enjoy the heat!

[71_Charger_R/T]

If your heater core isn't leaking, Just flush it! No need to go through all the hassle of replacing it.  It takes about 20 minutes with this little contraption/tool you can make up for less than ten bucks.  I've done dozens of cars and trucks and it's worked every time so far.
Just remove the core feed and return hoses as near the motor as you can (this just gives you an easier time hooking things up as hose is flexible and heater core nipples aren't.) I back flush first, then switch to forward flow flush and then back flush again, and so on until water comes out clear.  My method uses only water (preferably HOT) and some air pressure.


I hook the garden hose to my water heater and tool, I Hook my air hose to the tool also (both valves off on the tool ). Stick the pipe nipple from the "tool" into the return hose of the heater core (use hose clamps or you might get wet) Don't ask me how I know..... Stick the other hose into a bucket (I like to do this to see the amount of crud that comes out) If needed, I put a length of clear hose on to extent reach of hose to a bucket. Otherwise you can just let it splatter all over the ground if you don't care about the mess.
Open the water flow valve and a bunch of crud will come out.... Now introduce some air flow with the valve on the air line (not too much as these systems are generally only designed for about 16 PSI) then shut off the water and increase the air as the water diminishes to the point of no longer having a hydraulic capability. Then return air to moderate flow and give a brief shot of water to chug through the core. 
You should only need to do this a couple of times in each direction and everything will be clear.
G.M. vehicles that used the "Dexcool" coolant were very prone to losing heat and this has worked every time on them. I've also done it on Mopars too, So, Yes it works on them too!
Hope this helps!........ It's a whole lot easier than ripping apart your dash to replace the core.

[Tilar]

If your heater core isn't leaking, Just flush it! No need to go through all the hassle of replacing it.  It takes about 20 minutes with this little contraption/tool you can make up for less than ten bucks.  I've done dozens of cars and trucks and it's worked every time so far....

That's quite a gadget you have there, I'm going to keep this pic just incase... I did what Charger RT suggested using CLR and back flushed it a number of times. So far it seems to have done the job but I've only driven it from the farm to the house which is about 3 miles. 

[71_Charger_R/T]

 
Good! Glad you had a solution short of changing core!

[John_Kunkel]

Replace the heater core. It can be done in about 2 to 3 hrs. You don't need to disconnect the ac in those. You can work around it.

I had my '98 Ram core replaced by a dealer mechanic who'd done several of them and he disconnected the A/C lines. He claims there's no other way.

As fragile as those cores are I'd be real careful on the pressure used to back flush them, mine failed with only system pressure.

[Charger RT]

I'm glad it is working. The 80's and early 90's front wheel drive cars have heater core clogging issue. CLR is what alot of them use.
Tim

[rt green]

told ya

[dyslexic teddybear]

Interesting.......

Good reminder to me to flush the heater core when I replace the radiator in my 94 2500.....

Thanks for that reminder.....plan to try the CLR too.

[bull]

I am not sure if Rams had the same problems as Dakotas around the same model (my Dak is a 97), but it is a common problem in Dakotas to have no heat. The issue was with the heater core, the passage ways of the factory heater core were small and somewhat restrictive and doesn't take much to clog them up. The new ones you buy now are redesigned and actually shape differently, it comes with instructions because you have to make a couple of minor modifications to the heater core housing. You may want to try back flushing your heater core first, (I tried mine in my Dakota, and the heat worked... for about a day), if that doesn't help I would say replace the heater core.

Like others have said, it's a job, but if your handy with tools It can be done in a few hours. On my Dakota, you pretty much have to remove the entire dash, then unbolt the heater box for the firewall, then disassemble the heater box to replace the core. If you can do it yourself, by the time I bought the heater core, antifreeze, and a couple of other small things, I spent about 50 bucks.... best 50 bucks I spent on that thing... no more frosted balls.

Jason

My 94 Dakota is like that. I douched the heater core and it was great for about two months last spring but over summer it must have clogged back up again. I'm lucky if I can get it up to 60-degrees in the cab now.

[Stretch]

Replace the heater core. It can be done in about 2 to 3 hrs. You don't need to disconnect the ac in those. You can work around it.

I had my '98 Ram core replaced by a dealer mechanic who'd done several of them and he disconnected the A/C lines. He claims there's no other way.

As fragile as those cores are I'd be real careful on the pressure used to back flush them, mine failed with only system pressure.

I do it for a living. I've been a tech for 20+ years. I've done loads of them this way and have never had a issue.

[ws23rt]

In my case with my 98 Dakota I had heat but also a coolant smell and draining from the catch pan.
From here I read these heat exchangers are not long lasting.

If heat is not coming out a back flush may be worth a try first.  But it should not be expected to be a lasting fix.
BTW my AC evaporator (in the same box) was leaking as well.-- Do they have a similar reputation for life span?  Considering the hassle/cost to get at them it may be worth the peace of mind to replace both.