engine heats but heater core does not
 

hey i have a 91 four runner i got that was sitting for about 3 years not running and its not getting heat to the heater core unless i rev it to about 4k nd its intermidiate burst of heat it is not constant i am getting ready to change out the thermostat tomarrow have rad flush and kit to try to get some of the rust out is there any valves or any thing i should be aware of ?

I dont particularly know the answer to your question but I have read on another thread where guys with the same problem were taking the heater hoses loose at the firewall and hooking the water hose in there to blow out the rust. It worked for them.

Are you certain the coolant level is all the way up?

Be sure to use Toyota RED coolant~

thanks ima have to try flushing it straight with a hose or replacing it nd does the fluid HAVE to be the red toyota to heat the heater core ? ive got straight water and super flush in there now gotta pull it out tonight had a warm might here in alaska tonight its supost to freeze bought a new thermostat ima throw in b4 i change to antifreeze

Make sure you read the directions on the super flush. Youre supposed to run the engine with heater on full speed for a certain number of minutes. Engine has to run a while to insure the thermostat opens up and circulates the flush chemical.

You dont have to use a red toyota anti freeze.

Make SURE when you put anti freeze in it that you get the engine warm enough to open the thermostat open so antifreeze can circulate into your engine block.

You may have already know this but I want to make sure your block doesnt freeze tonight!

you can try a flush; I did it to my 91 pickup, and it worked FANTASTIC! all kinds of nasty junk came out, and afterward the heater worked great!

but a week later, the heater core sprung a leak; just a warning...

Hey! So i have been fixing up a little truck for a few months now. Got a great deal on it because all the drive-train and engine is just about new. Unfortunately, everything else needs MAD work.

I have recently added new sparks, cables and checked hoses. I popped in a new thermostat two days ago and did a coolant swap. BUT MY HEATER WASNT WORKING!

So, tried the heater core flush. It worked great! I still cant get my idle right but the heater is amazing. Heads up when you do this. The pressure needed to get a big blockage out is pretty hefty and you want to realllly gradually up the pressure till it comes loose. otherwise you can damage the heater core and no-one likes taking apart the dash to replace those things.

i set mine up like this (picture) and slowly upped the pressure till it broke the nasty black muddy clock free. kept upping the pressure till the hose was full tilt, then turned it off, connected the hose to compressed air and blew all the water out. Connected the hose to water again and did the same process. ANOTHER chunk came flying out.

Hope you get the thing working. It was way easier to flush the core than i thought it would be.

http://i964.photobucket.com/albums/a...oto_bpdwm1.jpg

http://i964.photobucket.com/albums/a...oto_byhpn1.jpg

thanks worked like a charm even tho i got two heater cores nd had to flush both after scratching my head for bout 30 minutes lol heater blows hot as heck now got some wires to chase haha

This is exactly what I needed! Thanks for the info and pics to help illustrate on how to do this flush! Hope that this will work for me too!

A few suggestions:
- Low coolant. Air bubble goes to the highest point in the coolant system (aka the heater core) and sits there.
Check the coolant level when your engine is stone cold.
- The switching valve can freeze sometimes and not allow warm coolant to enter your heater core.
-Leaves and junk blocking the air flow across the heater core.

Where is the "switching valve" located?

its right next to the firewall

and it was just 3 years of sitting getting rusty nothing froze up on me but woulda last night if i didnt go out for 3 hours of nothing but flushing till it was clear =D blows hot as heck

see the picture above were the hose is hooked up ? it should be were that hose origionaly went lil plastic box is the switching valve hope that helps his pictures helped me lots hope they help you bud

Oh, I now know where that is. Mine does open and close (Cold, the valve opens, pulling out to the engine, Hot, pulling in towards the firewall.) It seems to be working, but still get no heat after doing the flush....? Although, I did get a massive flood in the cabin where the passenger side is...

So whats the latest?

Replaced the heater core on my 4runner only to break the lever for the cold/warm lever! Damn. So I can't even tell if the heat is working or not...so many hours spent into fixing this to fix another problem. Crossing my fingers hoping it'll work after I replace the climate control, which means taking the whole dash apart....this blows.

*Update* I ended up fixing the climate control; a small plastic clip came off while I was switching the lever from cold to warm. Placed the plastic clip back and all was good. I started the truck back up and fired the heater...after a minute or two (since the truck was cold still) I finally got heat! After 10-12 minutes, the heater was fairly warm, not hot though, but I can deal with that. No more fogged up windshield in the morning plus the girlfriend appreciates the truck more since it now warms her up which is awesome.

yeah I've got the same problem in my 86 runner.

I found the switching valve, but it doesn't want to move even when I try to move it manually. My warm/cold switch doesn't work (it's loose but sometimes it wants to catch on something).

I think my switching valve is frozen up...what's the easiest way to fix it? Or does it have to be replaced?

Sounds like you have the same problem I had. What you can do before replacing it is to take off your dashboard, remove the climate control front panel (the panel with the labeling of the switches), unscrew the 3 screws holding the unit, and locate your heater valve switch, which should be a blue cable. Link that back to the cold/warm lever and I'm sure once you get there the lever should be out if place. Just toy around both the blue cable and cold/warm lever until you can actually move the valve. This will require you to hold firmly on the valve cable while sliding the cold/warm lever to the right or left to be able to move the valve switch. This worked for me and hope it will work for you. Good luck.