i can't take it anymore. it's too cold not to have heat in my truck. i already changed the fluid and thermostat, and it band-aided it for a few weeks, but now it's blowing cold air again. so i'm going to do it right and remove the heater core and clean it out. i've always known that this is what you do when suddenly your heat doesn't blow hot anymore, but i've never had to do it. any tricks on an 89 4cyl 4runner that i should know about before doing this?

 

you might want to try back flushing it before pulling the h/c. does your rig have a rear seat heater also? if so, you can run the rear heat so you dont freeze your dangling participles off!

any decent rad shop should be able to give you a few tips on r & r the h/c.

lee

 

no, no rear heat. not sure how to back flush it, to be honest. so far i've removed the passenger seat for ease of access. and now i'm tired, cuz the freakin bolts were rusty and it was a PITA to get them off! haha.

 

Back flushing involves removing both hoses (where they connect to the block and the radiator IIRC), then using a hose, or pressure washer, and blow all the gunk out of it.

 

i'm not sure about 4 runners, but on my supra, there's a vacuum controlled valve that opens when you turn the heat on, thus letting coolant into the heater core. look for such a valve on your 4 runner, it could very well be stuck in the closed position.

it'll probably look something like this:



see the metal bar on the bottom where it says "here"? if you have one of these valves, pull that metal bar up into the metal housing, and that should let coolant flow through the heater core.

if you don't have one or two of these valves, then i guess it's time to try back flushing.

-shaeff

 

a regular garden hose will be sufficient, a pressure washer can only lead to more problems due to the high pressure. on the firewall, in the centre, you will see a couple of hoses (prob 4 ttl). remove the top two, turn on the hose and hold it against one of the open barbed fittings. the water should come out the other fitting, let it run for a bit, then change the hose to the other fitting.

you should see some discoloured water come out during this process, continue until the water runs clear. you might want to flush the entire cooling system while you are at it.

lee