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Discussion Starter · #1 ·
Hello,
I recently purchased a 1997 rav4, it is a great driving car however the heater doesn't work. When I first bought the car the heat wouldnt come up to operating temp. I knew that the thermostat was bad so I replaced it. now it reaches operating temp but the heat still doesn't work. (by doesnt work what it does is it will get hot but then the heat fades to luke warm.) I then did a heater core flush(with a hose), it was disgusting. That didn't fix the problem. I then flushed the entire cooling system, and the heater core again. it seemed to work, but then the resevor got low and it stopped working. Yesterday I flushed the heater core with clr. I left it in for 3 hours then flushed it with a hose for 1 hour. The heater core has great flow. so i suspect that an air lock is the problem. The first gen heater cores are the highest point an the inlet and outlet hoses are 90 degree downward facing. Is there a good way to bleed out the air? ive tried everything. I used the radiator mounting funnel and ran the engine, revved it, got the fan to turn on, did it on a steep incline, drove it with the funnel attached. still nothing. I am unsure what to do. Again the heater core has great flow with a hose hooked up to it. The inlet and outlet get very hot(while car is running), but when you turn the blower fan on the outlet gets cold. Which means the heater core is blocked, by what i again assume to be air.
 

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Is it possible it is the HVAC blend door opening?
If it gets hot, sounds like the diverter in the duct work is allowing outside air to enter mixing with the heater core heat.

I don't know if an air pocket in the cooling system will prevent the antifreeze from staying warm (because that isn't something I know). Not a suggestion that you are incorrect.
 

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try this low cost purge funnel
that is the one i use and is a low cost.
connect to the radiator and fill with antifreeze.
then run the rav till the fans kick in.
and massage squeeze the driver side upper rad hose every couple of min.
you will hear the air purge in the system.
after the gauge on the dash reaches normal operational temperature.
shut down and leave the funnel in place till the rav is cold again.
and check the ds hose again for air in the system
then remove the funnel and use the plug t handle to keep the spillage at less than an oz.

this works well for me
try it!
 

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Discussion Starter · #5 ·
try this low cost purge funnel
that is the one i use and is a low cost.
connect to the radiator and fill with antifreeze.
then run the rav till the fans kick in.
and massage squeeze the driver side upper rad hose every couple of min.
you will hear the air purge in the system.
after the gauge on the dash reaches normal operational temperature.
shut down and leave the funnel in place till the rav is cold again.
and check the ds hose again for air in the system
then remove the funnel and use the plug t handle to keep the spillage at less than an oz.

this works well for me
try it!
I have that funnel and have done all of that to no avail
 

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Discussion Starter · #7 ·
Is it possible it is the HVAC blend door opening?
If it gets hot, sounds like the diverter in the duct work is allowing outside air to enter mixing with the heater core heat.

I don't know if an air pocket in the cooling system will prevent the antifreeze from staying warm (because that isn't something I know). Not a suggestion that you are incorrect.
the blend door works fine because the ac works and if you slide it to cold it gets very cold
 

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1998 Rav4, manual transmission, 2WD, 5-door, JDM engine installed in 2013
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the thermostat i got doesnt have one, Should i get one that does?
Yes, like IowaGold indicated, a thermostat with a jiggle valve is essential for bleeding air. To work correctly, the jiggle valve has to be properly oriented, at roughly the 12 o'clock position per the marking on the thermostat housing. Buy either an OEM thermostat or a Kuzeh thermostat, and no other. Kuzeh makes the thermostats for Toyota. The Toyota thermostat OEM p/n is 90916-03090. The Kuzeh p/n is 97YYQV. The gasket for the thermostat (a.k.a. the “water inlet housing gasket”) is OEM p/n 16325-63011, though often the gasket is included with the purchase of the thermostat.

I believe the Kuzeh thermostat these days may be bought at Napa and possibly even Autozone. To replace the thermostat, see Rav4world member Demoder's excellent guide at www.rav4world.com/threads/diy-replace-your-thermostat-get-your-cab-heat-back.172553/ . Also watch this great video by JonnyDIY:
 

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the thermostat i got doesnt have one, Should i get one that does?
yup get the ones like elle had posted the numbers.

that is how the air is purged with that valve in the system.
they have to have that to work right.
at least they are easy to get replaced.
and yes if you are careful to keep it clean you can recover the new antifreeze.

in a pinch i have also seen them drill a 1/8 inch hole in the thermostat and clock that at the 12 oclock on other cars and trucks.
but the right one works the best as that valve helps the air bubble get through.
and they are not that much money.
 

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Discussion Starter · #14 ·
yup get the ones like elle had posted the numbers.

that is how the air is purged with that valve in the system.
they have to have that to work right.
at least they are easy to get replaced.
and yes if you are careful to keep it clean you can recover the new antifreeze.

in a pinch i have also seen them drill a 1/8 inch hole in the thermostat and clock that at the 12 oclock on other cars and trucks.
but the right one works the best as that valve helps the air bubble get through.
and they are not that much money.
I have drilled the hole. I will let you guys know how it turns out
 

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Discussion Starter · #16 ·
yup get the ones like elle had posted the numbers.

that is how the air is purged with that valve in the system.
they have to have that to work right.
at least they are easy to get replaced.
and yes if you are careful to keep it clean you can recover the new antifreeze.

in a pinch i have also seen them drill a 1/8 inch hole in the thermostat and clock that at the 12 oclock on other cars and trucks.
but the right one works the best as that valve helps the air bubble get through.
and they are not that much money.
aftermarket try this one Beck Arnley Thermostat - 143-0728
cost as of 11/2022 10.61 shipped.
and clock the jiggle at 12:00 for best purge.
I drilled a hole and put it at 12. Also before all this if you hit the gas you could hear sloshing in the heater core
 
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