Poppie51

Hi, I am having trouble with the heater in my 1988 Toyota 4runner. I have replaced the thermostat, checked the valve on the firewall which operates to allow or prevent water from going through the heater core, back flushed the heater core and also have checked the flaps that operates when the dash controls are operated and still no heat at all. I haven't actually looked at the flap under the passenger dash but I can hear it openinng and closing when the control is operate. The engine heats up to normal operating temperature. As i'm writing this I began to wonder if maybe a heater hose is pluged, this is something I haven't checked but will do so. When back flushing the heater core the water came out clear from the beginning. I flushed it running the water into the inlet and also into the outlet but both ways the water was very clear. What am I overlooking? I have searched the web and have not found anything to solve my problem. Any help would be greatly appreciated. Thanks

muddpigg

iTrader: (1)

Did you burp it good? Pull it up on a curb or hill so rad is higher than heater core. Squat rear tires and put front on ramps/jackstands. Its still possible that the heater core is plugged.

Co_94_PU

iTrader: (-1)

The fins on the heater need to be clear of debris, no air flow means little to no heat front the vents. Debris falls through the cowl into the system when it is set to fresh air intake, you'll want to check the screens under there are intact and fashion new ones if needed.

You flushed the lines with the core didn't you? The only other suspect would be a clog in the head/intake runner. Verify flow in the system by removing the return and crank the engine over, add an extension to it and catch it in a bucket or add a section of clear hose for testing.

Poppie51

I haven't burped it. How is this done? Do I just pull the front tires up onto ramps and remove the radiator cap then start the engine and let it run for a little while? How can I be sure the heater core isn't plugged if running water through it isn't sufficient? How is the best way to be sure the fins are clear? Is there a way without having to tear the dash apart? I only flushed the core. I disconnected the hoses at the firewall where they connect to the core. It's dark and cold outside but i'm going back out to disconnect the return line to be sure water is flowing. Will also burp the system if I get a response shortly confirming the proper method of performing this task.

Poppie51

I disconnected the return line from the heater core and there was no water. After doing this I noticed there was also no water on the supply side of the heater core. The engine was at normal operating temperature and still no water on the supply or return side. I'm going to burp it tonight and hope that solves the problem. It's going to be 19 degrees here in Mississippi in the morning so I sure would like to have the heat working. I don't know how you guys who live up north handle the cold. We rarely have weather below 30 degrees so I can't imagine temperatures below 0 like many of you experience.

Co_94_PU

iTrader: (-1)

There is always supposed to be water circulation regardless of if the thermostat is open in the heater core, it only governs the return to the radiator, its only limited by the heater valve. Fwiw.

mholme

Poppie51

I tried burping the system but it seems the air just keeps coming. I don't have the special funnel i've seen on some videos but tried to use a regular funnel taped to the radiator, where the cap goes. It seemed to be getting air out but I kept repeating the process for over an hour and the air just keeps coming out.The way I was doing it was, with the front wheels on ramps I would fill the funnel and run the engine until the thermostat opened. When it opened air would come out and I would have to add more fluid. ( I repeated this for over an hour) Since the temperature is in the 20's it took a few minutes for the engine to heat up enough to open the thermostat but should it take over an hour to burp the system? I have never burped a radiator before so i'm not sure i'm doing it correctly. Does anyone have any advice? I'd like to know if i'm doing it correctly or where i'm making mistakes.

muddpigg

iTrader: (1)

You’re burping it fine. Sounds like something is off with coolant system. Did you visually inspect mixing valve? If it’s original it may be corroded and limiting flow.

I’ve never burped one that is taking as long as yours.

Its really cold here 19* sounds warm. Shoot getting over 0 with the sun out is warm.

If if it’s not the mixer valve then no way to pull heater core without removing dash.

L5wolvesf

Just to verify, are you saying that both heater hoses were bone dry?

Co_94_PU

iTrader: (-1)

^^ sounds like the valve is stuck closed, maybe the cable came off the valve, maybe off the dash end, or the plastic piece the selector arm rotates on is broken or unseated. Move the temp selector to both extremes and inspect the valve position.

To use a "bucket funnel" like the lisel you need to have room for lots of overflow the lisel is about a gallon and a half, and it must not run empty of fluid or leak. Your funnel is to small.

Raise the front end above the cowl line, some driveways are steep enough for this. Open your flush tee if you have one or pull the return line from the heater. Fill the radiator until you get fluid out of that line then reconnect it or put the flush cap back on. Cover the radiator inlet with your hand, then give the upper hose a little squeeze, to move about an inch of "head space" to the overflow tank. Make sure the overflow tank is filled to atleast the min line, and all three line connections are tight to it. (One at the radiator neck, one on the outside one inside the tank. Add clamps if needed, and or get new hose). Now run the engine up to temp. If all the air is out of the system you will see the coolant flow from your left to right in the radiator when the thermostat opens. If it climbs back up the neck you have air in the system or something else is (or went) wrong (loose lines, bad gaskets, worst case a crack in head, block, intake).

Poppie51

Muddpigg: I removed the mixing valve from the vehicle completely and blew air through it. It wasn't necessary to remove it from the firewall but I wanted to be certain it was working properly. Air passed fine when open, then I shut the valve and no air passed through. It seems to be working fine. / L5wolvesf : Yes, neither the inlet nor the outlet hose that connects to the heater core had any water. The heater core itself was full of water and the radiator and reservoir was also full. I ever started the engine with both heater core hoses disconnecter and no water came out. The engine has recently been rebuilt by a local shop so it seems as though there is a restriction in the line between the engine and the inlet line going to the heater core. If the line isn't clogged shouldn't either air or water come out of the line while the engine was running? I was expecting a smal amount of air to shoot out the hose followed by a stream of water. / CO94PU: I checked the cable and it is connected on both ends and working fine. The plastic piece the cable connects to in the dash needs replacing but I have it fixed temporary and it's working as it should for now. The valve is opening and closing easily when using the cable. Would placing the front tires on car ramps be high enough? That's the way I had it but I can get it higher if necessary? I have a flush tee so i'll try your advice tomorrow evening and will get back with you all on the results. Thanks to everyone for all the advice. It is very much appreciated.

Co_94_PU

iTrader: (-1)

If you cranked it over and had no flow(you said you disconnected the hose and got nothing?) You either have a blockage or the pump wasn't spinning. Do a quick visual on the belt, and wether the fan spins or not with the engine cranking or running.

muddpigg

iTrader: (1)

Its unlikely but possible that the is a blockage between the water pump, metal tube that attaches, or soft line the goes between metal tube and mixer valve.

Someplace along the line has a blockage be it rust (unlikely for a tube or hose) or wrong/incorrectly installed gasket. Gonna be a pain to get to.

wyoming9

iTrader: (1)

I have noticed if this is a 22re if the coolant level is to low you get no heat.

The incoming air needs to be set to fresh or you get little heat
New Thermostat Bad aftermarket have been real hit or miss.


Has the heat ever worked ??

I ran across one where a smaller radiator was installed dropping the filler neck enough to cause a no heat problem.

That about drove me crazy

Terrys87

iTrader: (1)

Are the heater hoses hot? I have seen dirt clog the heater core so bad that it cannot transfer heat. Here is a thread that could help if debris has gotten inside the AC system that will stop air flow. >>> https://www.yotatech.com/forums/f116...trucks-286766/

L5wolvesf

Given the 2 following statements:

I would say the water pump seems to be working – because no mention of overheating. Also, the heater core is clear.

Like CO and Terry indicate it seems like a blockage. Given that I suggest a simple test. With the rad cap off, disconnect the heater hoses, one at a time, where they go into the engine and see if any water comes out and at what rate.

Poppie51

I am going to work on the heater tomorrow, taking each suggestions one at a time until the heater is fixed. Hope to have good news the next time I post. Thanks for all the responses.

RAD4Runner

you just have to do it.
You can verify this if you included the hoses in the back-flushing loop, not just back-flush from the connection on the firewall.

Poppie51

I finally have heat. I checked for blockage in the lines and everything was fine so I began to burp the system again. It took about 30 minutes before air stopped coming out. I'm not sure why it took so long unless I was burping it wrong. I thought I had removed all the air the first time but obviously not. Last week the temperatures here were in the teens and I didn't have heat, now that I have heat the weather channel say the high this week is going to be in the upper 60's but i'm sure it wont be long before I will need the heater again. Thanks to all who have taken the time to offer advice, it is very much appreciated.