# losing heat at idle



## Centurion (Sep 5, 2002)

I drove my truck for about 20 miles and let it idle while my wife went into the store for a few minutes (it was around 0*F). As I sat there the temperature gradually got cooler and then cold. I tapped the throttle and right away the heat came back on strongly. The temp gage didn't move. It's not the coolant level as it is up there. I don't know if it was because of the exceptionally cold outside temps or what. Has anybody else experienced this phenomenon?


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## nissanmadness (Sep 18, 2006)

Centurion said:


> I drove my truck for about 20 miles and let it idle while my wife went into the store for a few minutes (it was around 0*F). As I sat there the temperature gradually got cooler and then cold. I tapped the throttle and right away the heat came back on strongly. The temp gage didn't move. It's not the coolant level as it is up there. I don't know if it was because of the exceptionally cold outside temps or what. Has anybody else experienced this phenomenon?


Check your belts.


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## jerryp58 (Jan 6, 2005)

Centurion said:


> I drove my truck for about 20 miles and let it idle while my wife went into the store for a few minutes (it was around 0*F). As I sat there the temperature gradually got cooler and then cold. I tapped the throttle and right away the heat came back on strongly. The temp gage didn't move. It's not the coolant level as it is up there. I don't know if it was because of the exceptionally cold outside temps or what. Has anybody else experienced this phenomenon?


I was looking to see how the flow of water through the heater hoses was controlled, but I couldn't find it in my service manual anywhere. I don't know if this will help any, but in a previous car, there was a valve in the heater hose line that was controlled by vacuum. If your truck has such a valve, maybe the vacuum line has a leak and it requires revving the engine to draw enough vacuum. Just a thought.


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## ChuckFrontier06 (Jul 25, 2006)

_*Water pump is probably worn enough that it won't flow enough coolant at idle to maintain sufficient heat. Have you ever replaced the water pump on your car?*_


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## himilefrontier (Jan 21, 2003)

My bet is that the thermostat is stuck in the open position, rather than closing when the temperature got too cold. This is better that stuck closed, but it is likely what is causing your problem. It is not keeping the coolant in the block and is circulating it through the radiator, which at those temperatures, will shed heat very quickly.


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## ChuckFrontier06 (Jul 25, 2006)

himilefrontier said:


> My bet is that the thermostat is stuck in the open position, rather than closing when the temperature got too cold. This is better that stuck closed, but it is likely what is causing your problem. It is not keeping the coolant in the block and is circulating it through the radiator, which at those temperatures, will shed heat very quickly.



_*If he drove it for 20 miles it should have heated the coolant sufficiently even with a stuck thermostat. He stated that if he tapped the throttle the heat came right back. The reason I said water pump is because I saw this very condition with a Nissan Quest. The water pump was eroded enough to the point it would circulate enough coolant under a load while driving but not enough at idle.*_


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## Win lowe (Dec 15, 2006)

jerryp58 said:


> I was looking to see how the flow of water through the heater hoses was controlled, but I couldn't find it in my service manual anywhere. I don't know if this will help any, but in a previous car, there was a valve in the heater hose line that was controlled by vacuum. If your truck has such a valve, maybe the vacuum line has a leak and it requires revving the engine to draw enough vacuum. Just a thought.


Of all the above replies I thinks this would apply more to your problem


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## Centurion (Sep 5, 2002)

OK....this is for my 2005 Frontier with less than 5,000 miles so it should be none of the above (I hope!).


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## jerryp58 (Jan 6, 2005)

Centurion said:


> OK....this is for my 2005 Frontier with less than 5,000 miles so it should be none of the above (I hope!).


It's still under warranty, right?


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## ChuckFrontier06 (Jul 25, 2006)

Centurion said:


> OK....this is for my 2005 Frontier with less than 5,000 miles so it should be none of the above (I hope!).


_*I was thinking it was the Sentra in your profile. In that case take it to the dealer so they can bleed the air out of the system. You don't drive that truck very much.*_


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## boogyman (Jan 24, 2005)

Ok I have noticed the same thing in our Pathfinder. We have the auto climate control. So the AC is on at the same time to regulate the temperature. I hit the AC off and it helps with the heat. Plus if you rev the engine a little, it helps with the heat. It's been like this since we first got it.


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## Centurion (Sep 5, 2002)

All right, turns out it was a bit low on coolant (I'd installed an e-fan back in June which required removing the top hose for clearance and I assumed the coolant in the reservoir would replace the lost coolant). I put in probably a large glassful of coolant but I haven't tested it out yet as far as the original problem. I doubt such a small quantity would make a difference, but who knows. 

But what I don't get is that the overflow bottle was showing above the min level. Why didn't it suck in the coolant from the reservoir?


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## Win lowe (Dec 15, 2006)

If it's not sucking back the coolant it could have a small leak in the hose and it would suck air instead of coolent


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## Oldnissanguy (Jan 6, 2005)

Or your radiator might be messed up.


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## Oldnissanguy (Jan 6, 2005)

OOPS! Radiator cap.


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