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Discussion Starter #1 (Edited)
I have a 98 2500 V10. Bought it with 96000. Heater worked great, temp gauge worked perfect. Did an oil change at 100K a few weeks ago and they said my radiator overflow bottle was empty. They filled it and a few days after that my heater stopped blowing hot AND my temp gauge stopped working. I checked my overflow the other day and it was a lil low so i filled it. Wen i filled the overflow I also popped the rad cap (engine cold) and i heard a sucking sound in the overflow bottle then it burped some coolant out the cap at me. Nothin crazy like it was pressurized or hot coolant though. So im assuming the rad was full.
I dont smell coolant wen the heat blows so i dont think the core is leaking. And theres never any fluid on the ground or wet areas on the engine/in the engine bay so i dont think theres any external leaks. The mechanics said there was no signs of leaking fluids anywhere when i got my oil changed. I watched them do everything from start to finish.
I have noticed the notorious gurgling/bubbling sound in the dash but it got less noticeable after i refilled the overflow bottle the other day.
The air seems to blow harder wen i turn the fan down one click and put it on face vents and it seems to blow a lil warmer wen i set the temp knob one click down from hottest setting. But it takes forever to even get that warm and its still only warm enough to defrost the windshield.
No CELs, mpg is same as usual, truck idles perfect, old oil wasnt milky wen i got it changed, and new oil since then is fine so i doubt the head gaskets cracked.

I dont wanna fork out the money for a new heater core or Tstat until ive checked other possible issues. Ive looked at other threads and i didnt see anyone with similar enough symptoms so i figured itd be a good idea for a new thread.

Any help is appreciated ����
 

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I have had these issues with past vehicles, turned out to be the thermostat stuck in the open position. The coolant constantly circulates through the engine not allowing the engine to get up to proper operating temperature, in turn this doesn't allow the heating core to push hot air.
 

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If it is the thermostat, be happy it didn't get stuck in the closed position, you might have been replacing a headgasket.
 

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I have a 98 2500 V10. Bought it with 96000. Heater worked great, temp gauge worked perfect. Did an oil change at 100K a few weeks ago and they said my radiator overflow bottle was empty. They filled it and a few days after that my heater stopped blowing hot AND my temp gauge stopped working. I checked my overflow the other day and it was a lil low so i filled it. Wen i filled the overflow I also popped the rad cap (engine cold) and i heard a sucking sound in the overflow bottle then it burped some coolant out the cap at me. Nothin crazy like it was pressurized or hot coolant though. So im assuming the rad was full.
I dont smell coolant wen the heat blows so i dont think the core is leaking. And theres never any fluid on the ground or wet areas on the engine/in the engine bay so i dont think theres any external leaks. The mechanics said there was no signs of leaking fluids anywhere when i got my oil changed. I watched them do everything from start to finish.
I have noticed the notorious gurgling/bubbling sound in the dash but it got less noticeable after i refilled the overflow bottle the other day.
The air seems to blow harder wen i turn the fan down one click and put it on face vents and it seems to blow a lil warmer wen i set the temp knob one click down from hottest setting. But it takes forever to even get that warm and its still only warm enough to defrost the windshield.
No CELs, mpg is same as usual, truck idles perfect, old oil wasnt milky wen i got it changed, and new oil since then is fine so i doubt the head gaskets cracked.

I dont wanna fork out the money for a new heater core or Tstat until ive checked other possible issues. Ive looked at other threads and i didnt see anyone with similar enough symptoms so i figured itd be a good idea for a new thread.

Any help is appreciated ����
You are describing a system with air in it.
1: the burbling sound, is air in the system, and a fair amount of it.
2:if the air is hotter when you turn down the fan,it points to a "not full" heater.(air in it)

In the old days before the overflow reservoir, the coolant used to drip on the ground when the radiator cap got to it's set pressure, and that coolant was lost for good. Since it took a few minutes for the rad. cap to open at about 15psi, you would be driving by then, so you wouldn't see it on your driveway.

Now, with the overflow bottles, the excess coolant goes into the bottle when the cap. cracks open when the expanding coolant reaches a pressure of about 15 psi. When the coolant cools down, a vacuum is created in the rad.( volume of water reduces) and the coolant in the bottle gets sucked back in the rad. There is a hot "full" line on the bottle, and a cold one...this is important.

Although you've refilled the bottle,(to the proper line) you now need to bleed the air out of the system.
The best method is to have the front end up, the engine fully warmed up,(thermostat open)the rad. cap off, and the engine speed above idle to assure a good flow in the engine, so the air is pushed out. Air bubbles can be tiny, so it may take a couple of minutes to bleed it all out.
Some people make up a tube of sort and stick it in the rad. to keep it from splashing too much.
Air in the heater system is a common cause of low heat from the heater, and can lead to higher than normal engine temp. (air in the rad. or engine)
Good luck
 

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Discussion Starter #5
You are describing a system with air in it.
1: the burbling sound, is air in the system, and a fair amount of it.
2:if the air is hotter when you turn down the fan,it points to a "not full" heater.(air in it)

In the old days before the overflow reservoir, the coolant used to drip on the ground when the radiator cap got to it's set pressure, and that coolant was lost for good. Since it took a few minutes for the rad. cap to open at about 15psi, you would be driving by then, so you wouldn't see it on your driveway.

Now, with the overflow bottles, the excess coolant goes into the bottle when the cap. cracks open when the expanding coolant reaches a pressure of about 15 psi. When the coolant cools down, a vacuum is created in the rad.( volume of water reduces) and the coolant in the bottle gets sucked back in the rad. There is a hot "full" line on the bottle, and a cold one...this is important.

Although you've refilled the bottle,(to the proper line) you now need to bleed the air out of the system.
The best method is to have the front end up, the engine fully warmed up,(thermostat open)the rad. cap off, and the engine speed above idle to assure a good flow in the engine, so the air is pushed out. Air bubbles can be tiny, so it may take a couple of minutes to bleed it all out.
Some people make up a tube of sort and stick it in the rad. to keep it from splashing too much.
Air in the heater system is a common cause of low heat from the heater, and can lead to higher than normal engine temp. (air in the rad. or engine)
Good luck
My only question about this is, my temp gauge went from working normally to not working at all? If it was air in the system, wouldnt my temp spike?
 

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""""""""""""""""""My only question about this is, my temp gauge went from working normally to not working at all? If it was air in the system, wouldnt my temp spike?""""""""""""""""

Your temp. gauge should in fact still indicate something even with air in the system; if it's dead, then the unit is defective, or the wiring is broken, or disconnected; it looks like a separate issue to me. I don't know if there's a fuse for the unit? you could test...
 
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