kennycess

My 89 4runner has had a motor swap done by the previous owner from a v6 EFI to a 86 22r and they did a fairly decent job. I have no heat. I started with the easiest and cheapest parts first. I replaced the thermostat and water pump (checked both old thermostat and water pump and both were fine) I then looked into the heater core, even though water flowed through it with a garden hose I still just replaced it. To cancel out any suspected blockages I have both hoses running straight from the block directly to the heater core then right back to the block. I took off both lines coming from each side of the block and there is no pressure, they do not flow at all. My engine is not overheating, but will not cycle water. Is their a possibility they are both return lines or it is plumed wrong? Also water pump teeth look like they should spin the opposite way they do. But everything is stock and matches with the specs including belt diagram. I am out of ideas.

pascoscout

Unless theres a checkvalve in the line (never seen one) the direction of flow to the heater core shouldn't matter. So long as water moves through it you'll get heat so there is no dedicated "return" line.

You're certain the thermostat is opening? Dumb question but you didn't install it backwards did you? Would act as a check valve in that case. May need to take off both hoses at the radiator and see if you can flow water through the engine with a hose. Even if the thermostat is closed a minor amount should come through. Also try taking out the thermostat altogether and flowing water through the engine.

You say it's not overheating but how far/long are you driving it and what's the temperature outside? If water isn't moving the engine will overheat, may take a little bit but it will.

kennycess

Water flows through the engine great without any resistance. And the thermostat is installed correctly. I will try to take it out and rule out the thermostat.

I have been waiting for it to overhead any day but it still does not. Sometimes over an hour straight at highway speeds at a 50-60 degree temp. I have never been this stumped before.

Marc

Do your upper and lower rad hoses get hot?

kennycess

Yes they both get hot

kennycess

Water flows through the engine great without any resistance. And the thermostat is installed correctly. I will try to take it out and rule out the thermostat.

I have been waiting for it to overhead any day but it still does not. Sometimes over an hour straight at highway speeds at a 50-60 degree temp. I have never been this stumped before.

pascoscout

If the upper and lower hoses are hot you should be getting water moving through the engine. If it wasn't circulating only one side would get hot. Based on how far your able to drive without overheating I don't think your issue is with water circulating through the engine.

Gonna sound like a tech support department here but:

For the ports coming off the block to the heater core have you taken the hoses off and turned the motor over (or on even) to see if coolant comes out? Maybe the port itself is plugged somehow.

Water moves freely through the radiator (upper to lower outlets)?

Have you measured the temperature with an infared gun to see what the hoses, block, etc are getting up to?

This really is a stumper.. I can't think of anything else that would be obvisouly wrong considering you've replaced the parts that would normally cause this type of issue.

kennycess

Yes both radiator hoses are hot and I am running around 190. So weird! But I have heat now. I just decided to run a hose from the thermostat hosing from one of those 3/8 plugs and went to one side of the heater core then back into the engine and she has heat now and is not overheating. I am sorta irritated I still don't know what's wrong but I'll live. Thanks for the help!

Gevo

Have you checked your heat control valve? It should be just to the left of the break booster, and is mechanically controlled (via wire) by the lever in the car. Easy to remove and check operation. It's the thing at the bottom of page AC 36
http://personal.utulsa.edu/~nathan-b...g/25heater.pdf

pascoscout

There ya go. Never encountered a car with an inline valve like that (not that my experience is extensive) but if it cuts off flow that could be your issue.

kennycess

My lower hose is not getting hot only my upper rad hose. Does this mean my radiator is clogged? My thermostat water pump and heater core are brand new

kennycess

Only my top rad hose is getting hot.

Gevo

Kennycess,

its very easy to remove your lower hose and see if your radiator is clogged. I doubt it, it would take a long time of sitting around for this to happen. Just undue whatever hose clamp there is on teh radiator side, pull it out and put water in from the top, if it freeflows you are ok. Put distilled water and antifreeze back in!

You may have a bad water pump, any leaks?

kennycess

Just replaced water pump. Small leak but nothing serious. Water doesn't seem to be cycling still but my truck overheats only when it is idling for a while like when I warm her up In the morning.

pascoscout

On the V6 I think the lower hose is the return from the engine, assume its the same on a 4cy. If that hose is not getting hot you're not getting flow through the engine.

Have you replaced the radiator cap? If its not holding pressure could cause issues. Its actually the first thing listed to check for overheating in the service manual but is often overlooked.

Any leak, even a small one can cause pressure loss too. I'd fix that leak before doing much else.

Did you check the fluid coupling (aka clutch) on your fan? If you only overheat while sitting could be an issue with that not keeping the fan speed up at idle.

Was the 22r rebuilt? If not did you flush it to make sure the galleries are clear? Have you checked to make sure you aren't getting water in the oil?