How Hot Should Heater Get?
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Elder User
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How Hot Should Heater Get?
On my '74 F-100 I know it is getting up to operating temp as my factory temp gauge actually works very well. Even when it's fully warmed up the heat I get out of the heater doesn't seem to be terribly hot. Luke warm would be a better description. All the controls work just fine to transfer from floor to defrost and such, it just never seems as warm as it should be. Since my truck didn't have AC the only options I have are floor and defrost and for that to do a lot of good it seems like it should blow HOT air.
Is luke warm as good as it gets or am I probably looking at a partially clogged up heater core?
Is luke warm as good as it gets or am I probably looking at a partially clogged up heater core?
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Joined: Oct 2010
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From: S.W. Montana
On my '74 F-100 I know it is getting up to operating temp as my factory temp gauge actually works very well. Even when it's fully warmed up the heat I get out of the heater doesn't seem to be terribly hot. Luke warm would be a better description. All the controls work just fine to transfer from floor to defrost and such, it just never seems as warm as it should be. Since my truck didn't have AC the only options I have are floor and defrost and for that to do a lot of good it seems like it should blow HOT air.
Is luke warm as good as it gets or am I probably looking at a partially clogged up heater core?
Is luke warm as good as it gets or am I probably looking at a partially clogged up heater core?
The heat in my 1973 F100 gets nice and toasty. Within 10 minutes of being turned on (at idle, at least), the cab is hot enough that I can take off my coat and my hat and still be hot. This happens even in the cold temps that we've been having here (e.g., single digits above 0F). The temperature gauge reads normal when blowing hot air, and I've no reason to believe that the thermostat or gauge is faulty.
Stay warm -
Fish
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Joined: Aug 2010
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From: Vancouver, WA
Check to see that the actual water temp is where it's suppose to be. I had a bad sending unit in one 77' I had and it showed hot but wasn't. I also found that eventhough the control ***** worked the actual doors on the vents didn't move right to give good control, air leaks everywhere.
Post Fiend
Joined: Jul 2004
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From: Northern California
Five or six things it could possibly be...
1) Heater Core water passages plugged, or fins clogged with debris.
2) Heater Box seals bad, alowing cold air to seep around the heater core.
3) Engine coolant Thermostat not operating properly, incorrect heat range, opening too soon or missing.
4) Low on Coolant, or overfilled.
5) Debris in the cowl and fresh air vent systems. Remove the fresh air vents on both sides of the cab, and dig down deep into the bottom and pull out the debris to alow proper air flow.
6) temperature control cable misadjusted.
etc...
1) Heater Core water passages plugged, or fins clogged with debris.
2) Heater Box seals bad, alowing cold air to seep around the heater core.
3) Engine coolant Thermostat not operating properly, incorrect heat range, opening too soon or missing.
4) Low on Coolant, or overfilled.
5) Debris in the cowl and fresh air vent systems. Remove the fresh air vents on both sides of the cab, and dig down deep into the bottom and pull out the debris to alow proper air flow.
6) temperature control cable misadjusted.
etc...
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Check to see that the actual water temp is where it's suppose to be.
On a cold day such as today I can start it up and I can drive and watch the temp gauge climb towards somewhere around MP as the coolant in the engine warms up. Then when the thermostat opens up and ice cold water starts rushing in from the radiator the gauge will drop like a rock to somewhere around E and this process will repeat itself, slightly less pronounced each time until it finally reaches a fairly steady state of equilibrium.
I can conclude, therefore, that the gauge is working exactly how it's supposed to be.
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You can check the heater core by comparing the temp of the heater hoses going into it. They should be nearly the same temp. If one is significantly cooler than the other that indicates plugged core. I changed the heater core in a '79 non ac about 20 years ago and remember it being a pretty simple job.
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So I hear, but me and heater cores don't get along too well. On my Corvette the heater core is about the first part down the assembly line and everything else is bolted to it. On my Camry it should have been easy except that the replacement wasn't exactly right and required modification in order to fit and not leak. 20 minute job there turned into about 3 days worth of pain in my ***.
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Elder User
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Yeah mine barely keeps up with the air leaking through the cab when I'm moving, wouldn't even begin to think about compensating for an open windows. I'll drive it tonight and then check the heater hoses and see if they are markedly different in temperature.
Many years ago my step-grandfather had the engine rebuilt because some idiot told him that the engine was worn out and that was causing his chronic overheating problem. Naturally the overheating problem wasn't solved with the rebuild and the radiator was found to be clogged somehow. I don't know if they flushed it or replaced it, but I know that if the radiator was clogged up, it would be a fair bet that the heater core could be too.
When I first got the truck the coolant didn't look that great. I flushed it by way of draining the radiator and refilling with clean water, running the engine, and repeating until such time as I only got clean water out of the radiator, then drained it again and added coolant until I got the proper mixture. So in no way was the heater core power flushed. I need to do that, but I really need to do it at my dad's house. He has 90 PSI of water pressure whereas I only have around 25
Many years ago my step-grandfather had the engine rebuilt because some idiot told him that the engine was worn out and that was causing his chronic overheating problem. Naturally the overheating problem wasn't solved with the rebuild and the radiator was found to be clogged somehow. I don't know if they flushed it or replaced it, but I know that if the radiator was clogged up, it would be a fair bet that the heater core could be too.
When I first got the truck the coolant didn't look that great. I flushed it by way of draining the radiator and refilling with clean water, running the engine, and repeating until such time as I only got clean water out of the radiator, then drained it again and added coolant until I got the proper mixture. So in no way was the heater core power flushed. I need to do that, but I really need to do it at my dad's house. He has 90 PSI of water pressure whereas I only have around 25
Post Fiend
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From: Northern California
If the Radiator was plugged in the past, the heater core being plugged is a high possibility.
You can flush the heater core by removing the hoses from the engine and hooking up a garden hose. Flushing it this way, may or may not work, and it could cause the old core to leak if its plugged too badly with crud.
If you do need a Heater core replacement. Try and get a FORD replacement heater core. They cost three times as much as a aftermarket one, but are well worth it in the long run, as they are also three times the quality, and they fit perfectly. This is also where a junkyard Factory core is can be desireable over crappy aftermarket.
You can flush the heater core by removing the hoses from the engine and hooking up a garden hose. Flushing it this way, may or may not work, and it could cause the old core to leak if its plugged too badly with crud.
If you do need a Heater core replacement. Try and get a FORD replacement heater core. They cost three times as much as a aftermarket one, but are well worth it in the long run, as they are also three times the quality, and they fit perfectly. This is also where a junkyard Factory core is can be desireable over crappy aftermarket.
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That's really why I'm leaning towards heater core as opposed to another problem currently, just because I know a little history. I don't HAVE to drive the truck, I have plenty of other things to drive. So, it being 26* today I think I'll just let it be. Supposed to make it up to 50 on Friday and the wife will be out of town so then would be a good time to mess with it.
