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86-95 Trucks & 4Runners 2nd/3rd gen pickups, and 1st/2nd gen 4Runners with IFS

heater not getting hot

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Old Mar 7, 2008 | 05:30 PM
  #1  
jdw1's Avatar
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From: Texas
heater not getting hot

my freaking heater takes way too long to heat up, and when it does, its not hot its just a little warm. do i need a a new heater core or possibly a hotter thermostat?
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Old Mar 7, 2008 | 05:49 PM
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From: Dillsburg, PA
check your coolant level first.
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Old Mar 7, 2008 | 06:05 PM
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From: Texas
coolant level is fine
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Old Mar 7, 2008 | 06:26 PM
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From: Manassas, VA
If the coolant temperature is low it will prevent the heat from getting hot.

try a t-stat
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Old Mar 7, 2008 | 06:30 PM
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From: GrangeVille, Idaho
The stock thermostat is 190*- 195* if you have a lower temp thermostat your heater won`t get as hot as it should, also check to make sure the heater control valve is opening, just because you push the heat lever to hot doesn`t mean its opening all the way, visually check it. if none of this helps then its probably the heater core. replacing the heater core isn`t as hard as it looks, you do have to remove the complete dash to get to the heater box, ive done two so far and it takes about four hours start to finish.
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Old Mar 7, 2008 | 06:32 PM
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From: Oklahoma State
It could be your t-stat is stuck open, or you could have trapped air in the heater hose or a clogged heater core. You don't even want to know how hard it is to replace a heater core, try back flushing it from the engine bay first.

Last edited by mt_goat; Mar 7, 2008 at 06:35 PM.
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Old Mar 7, 2008 | 06:38 PM
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From: Texas
where is the heater control valve? how do i check that it is opening all the way? i changed my thermostat about 10,000 miles ago when i changed out my engine. is there any threads on heater core replacement?
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Old Mar 7, 2008 | 07:33 PM
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CJM
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From: Central NJ
Heater core is most likely clogged..
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Old Mar 7, 2008 | 07:45 PM
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From: Oklahoma State


BTW you don't have to take the engine out, but it sure makes back flushing the heater core easier hehe.

Last edited by mt_goat; Mar 7, 2008 at 07:47 PM.
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Old Mar 7, 2008 | 07:53 PM
  #10  
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how do i clean or flush out the heater core?
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Old Mar 8, 2008 | 05:26 AM
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From: Oklahoma State
This is what I'd call back flushing:
First make sure the heater valve is open and disconnect both heater hoses ("in" and "out" hoses), and stick a garden hose in the "out" hose and gently turn it on, Don't shoot water in full blast, normal household water pressure can exceed 100 psi and an old heater core might rupture from the pressure. Run water in untill it flows clean, then reverse the direction (water flow into the "in" hose) untill it flows clean. Repeat in other way again.

An easier and less messy way of doing it (but less effective too) is to drain the cooling system and leave the radiator cap or hose off. The idea is to allow air into the system for the next step. Disconnect the "in" hose and using a shop vac gently apply suction to the "in" line. You can increase the vac pressure by wrapping your hand around the end of the hose to help seal the air flow, but don't apply too much suction too fast. Again be gentle with that poor old heater core because if it ruptures or starts leaking you will be stuck pulling the whole fricking dash out to replace it, like Myyota said, 4 hours of work if you know what you're doing.

If you still have the factory heater hose clamps with a pin they are practically impossible to get back on. I just replaced them with screw clamps or spring type clamps (better).

Last edited by mt_goat; Mar 8, 2008 at 05:32 AM.
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Old Jun 3, 2008 | 04:17 PM
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by the way Autozone sells Prestone brand kits with instructions on the back of the package.
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Old Jun 3, 2008 | 04:24 PM
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From: Hills of Vermont
For the cost of the thermostat and gasket and the ease of install, I'd try that. Couldn't get my truck to warm up and it was the thermostat.
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Old Jun 3, 2008 | 04:25 PM
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From: Lake City, Fl
Originally Posted by vtjeenyus
by the way Autozone sells Prestone brand kits with instructions on the back of the package.
oh wow, 1st post and dug up a 3 month old thread to post in...

oh, and by the way... the kit they sell is designed to flush the radiator; it rarely flushes out the heater core too. do as mentioned above to get it done right...
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