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Loss of heat stopped at idle.
Posted: Mon Nov 14, 2022 3:01 pm
by AS_The_Crow_Flys
Never had this happen before, but i was idling on the road while waiting for some road work to let me through this AM and after a couple minutes my heat went from HOT to pretty much outside temp. I did not have recirculate on.
Anyone know if this is normal or should I be checking something.
Re: Loss of heat stopped at idle.
Posted: Mon Nov 14, 2022 7:33 pm
by VStar650CL
Usually it means the coolant is a little low. The heater core is one of the highest points in the system on R51's (and the related Frontiers/Xterras), and automotive water pumps don't generate much head pressure. So it only takes a minor loss of coolant to cause the heat to vanish at low RPM.
Re: Loss of heat stopped at idle.
Posted: Mon Nov 14, 2022 7:49 pm
by AS_The_Crow_Flys
VStar650CL wrote: ↑Mon Nov 14, 2022 7:33 pm
Usually it means the coolant is a little low. The heater core is one of the highest points in the system on R51's (and the related Frontiers/Xterras), and automotive water pumps don't generate much head pressure. So it only takes a minor loss of coolant to cause the heat to vanish at low RPM.
Ah good tip, thanks. I will go check that after I get the kids to sleep. I haven’t noticed any signs of leaks but you never know.
Re: Loss of heat stopped at idle.
Posted: Mon Nov 14, 2022 11:07 pm
by AS_The_Crow_Flys
Put a little under half gallon in and then did a bit of idling and it got up to around 100 at the upper return tube and I lost patiences with waiting for it to heat up so I took a little drive to warm it up.
It was about 160 and then started dropping when I parked it.
I may have a stuck thermostat but I will test further later.
No signs of a leak as of yet.
Re: Loss of heat stopped at idle.
Posted: Tue Nov 15, 2022 7:15 am
by VStar650CL
AS_The_Crow_Flys wrote: ↑Mon Nov 14, 2022 11:07 pm
Put a little under half gallon in and then did a bit of idling and it got up to around 100 at the upper return tube and I lost patiences with waiting for it to heat up so I took a little drive to warm it up.
If it was half a gallon low, then the core may be airbound. You might need to bleed the system.
Re: Loss of heat stopped at idle.
Posted: Sun Nov 20, 2022 9:33 am
by palmerwmd
I had this happen to me before.
Put the nose up on a tall curb at end of a hill cul de sac..\
let it sit overnight and then filled it up.
Good opportunity to refill it a bit thin like add some distilled water since that increases heat capacity.
As a Chemist and a former speed racer tuner I can also recommend :
https://shop.advanceautoparts.com/p/red ... lsrc=aw.ds
This reduces surface tensions and cavitation at the waterpump.
helps flow of coolant so increases heat exchange at the cooling fins.
there are all very small effects but a little bit helps when you tow in summertime.
Re: Loss of heat stopped at idle.
Posted: Sun Nov 20, 2022 1:16 pm
by TooMuchControl
Put your ear to the glove compartment. Or bette yet, have an assitant in the passenger seat put their ear to the glove box / dahsboard area.
Tap the throttle.
If you hear chirps, you have zee bubbles in the system - air. It's very noticeable if you can get into a garage.
Just let it idle and tap the throttle and you will year what might be a squeaky wheel. One almost thinks it's a squeaky belt noise. Air.
I wonder if you run your rear heater? Our small heater pipes run to the back heater core and sometimes pipes corrode and a leak develops there, right at the frame, above where the muffler and the rear pipe meet. It's a known issue, and I had to fix mine 2-3 years ago. A couple of drops appear on the driveway, but that muffler seems to dry the drops out. Looks for corrosion and green crusty fluid too.
Re: Loss of heat stopped at idle.
Posted: Sun Nov 20, 2022 10:34 pm
by palmerwmd
TooMuchControl wrote: ↑Sun Nov 20, 2022 1:16 pm
Put your ear to the glove compartment. Or bette yet, have an assitant in the passenger seat put their ear to the glove box / dahsboard area.
Tap the throttle.
If you hear chirps, you have zee bubbles in the system - air. It's very noticeable if you can get into a garage.
Just let it idle and tap the throttle and you will year what might be a squeaky wheel. One almost thinks it's a squeaky belt noise. Air.
I wonder if you run your rear heater? Our small heater pipes run to the back heater core and sometimes pipes corrode and a leak develops there, right at the frame, above where the muffler and the rear pipe meet. It's a known issue, and I had to fix mine 2-3 years ago. A couple of drops appear on the driveway, but that muffler seems to dry the drops out. Looks for corrosion and green crusty fluid too.
Can you provide a picture of that pipe and the spot where it likes to corrode?
I would be grateful
Re: Loss of heat stopped at idle.
Posted: Mon Nov 21, 2022 9:53 am
by TooMuchControl
I'm having issues trying to upload pictures,
One of the last places anyone will look for a radiator leak - at the rear of the truck!
These sneaky heater lines run right on the frame, inside the rear passenger wheel. If you remove the rear passenger side wheel, you have easy access to see it.
This was a previous thread I dug up...
coolant-smell-at-front-of-vehicle-t14982.html
Re: Loss of heat stopped at idle.
Posted: Mon Nov 21, 2022 12:28 pm
by AS_The_Crow_Flys
Hi All,
Thanks for all the comments. I wouldn't be surprised if there is a small leak in the system. Also i did notice a whirring noise that i thought was the fan wearing when the coolant was low. I haven't noticed it since i topped it up. I also did the heating things to get it up to temp as best i could. Its hard to get my system above 170 with the cold (for here whether around mid 30s).
I still suspect a stuck thermostat and will look into it in the future, but for now still going and heats working.
Thanks
Crow
Re: Loss of heat stopped at idle.
Posted: Sat Dec 03, 2022 2:30 pm
by Zen_master
Same thing happened to mine. Posted about it on these boards a while ago.
topic12776.html
The heat would fluctuate with the throttle.
After much tinkering, the eventual fix was a failing shutoff valve in the heater hose. Replacement of the HVAC heater hose inlet solved it. This was on the V8 FYI.
Re: Loss of heat stopped at idle.
Posted: Tue Feb 28, 2023 11:50 am
by 521ton
Same issue, mine turned out being a bad radiator. Bottom tank seal, and upper tank seal were shot.
Re: Loss of heat stopped at idle.
Posted: Tue Feb 28, 2023 12:04 pm
by ShipFixer
There is a booster pump for the heater circuits on the firewall, just to the inside of the steering column. It's on the line that takes hot coolant off the driver side of the engine and routes it to the top of the heater inlets on the passenger side. I don't think I've heard it make noise but it is technically a high point in the system. So if you are not getting heat in either core and there's whirring, and it went away when you topped it off, that's probably where that noise was coming from.
Re: Loss of heat stopped at idle.
Posted: Wed Apr 05, 2023 8:46 am
by palmerwmd
Zen_master wrote: ↑Sat Dec 03, 2022 2:30 pm
Same thing happened to mine. Posted about it on these boards a while ago.
topic12776.html
The heat would fluctuate with the throttle.
After much tinkering, the eventual fix was a failing shutoff valve in the heater hose. Replacement of the HVAC heater hose inlet solved it. This was on the V8 FYI.
Glad you got it sorted!
Re: Loss of heat stopped at idle.
Posted: Wed Apr 05, 2023 8:47 am
by palmerwmd
521ton wrote: ↑Tue Feb 28, 2023 11:50 am
Same issue, mine turned out being a bad radiator. Bottom tank seal, and upper tank seal were shot.
Its good that u spotted the bad radiator beofre it became an even bigger prolem ..
Seems to me this symptom of intermittent heat can have several distinct causes.