paulaugood

High

Bought my first toyota a 10 days ago (1994, 2.4) I like it but...

My little 94 pickup is not putting out much heat. If the fan is on low the air is warm, fan on high air goes cold. I replaced the thermostat - well there was not one in it - no change. Also the top of readiator is hot, bottom relatively cool. Had a lot of liquid loss for about a week - think the cap was leaking - replaced it an liquid loss stopped. Wondered if the water pump was not pumping well. My thinking is if it was a blocked radiator core then I would get heat in passenger area. I tried squesing the top radiator hose to feel if water pump would buildup any pressure. I cant feel any flow although befor I put in the missing thermostat I could see coolant moving in the top of the radiator.


I have searched the post and they all seem to include overheating - judging by the temperature guage this is not happening.

Any ideas?

Robrt32

When i first bought mine, it was the same thing as yours, no therm. I put 1 in and the heater did not heat right.. I went along there a few more days and it started steaming out the tail pipe.. I come to figure out that the head was bad.. and someone had filled it with stop leak.. with the exrtra pressure form the therm, the sealant had give away....... I hope you get luckier than i did

habanero

Heater control valve? Blocked heater core? Air bubble?

Alperovich

i 2nd /\.

What you should do, is start the car, wait for it to warm up to operating temp,
check the top hose, it should start to get warm, once thats done

turn on the heat, you should start to feel the the heater inlet line get warm, as should the return but not as hot.

if the inlet will be really warm and the other cold, or slightly warm. Which would indicate either a heater contorl valve or blocked heater core.

At this point, pull off both heater line and make sure to keep them high in the air (not to spill coolant), and take a hose and run water into the heater core and it should flow really well, a lot of time you'll see it spit something out and it'll start to flow better. Reinstall, bleed and test the system again and check the heater control valve

Now if when you the heater inlet line was COLD or warm, you have a water pump issue!

paulaugood

Thanks for replies.

I read some threads about air locks so I tried burping the system - it bubbles a little then wham - coolant every where - seemed to be boiling over. Had a new pump at hand so thought I would put it on. Maybe a mistake!

The old pump was fine - impelor had some slight ware but ok. I'd come this far so I put it on. Checked flow through heart core with hose - seemed ok, flushed radiator. Put it all back together filled up with fresh coolant and took it down the road. Heater was good. Stopped for gas. Carried on down the road as I found a few missing bolts here and there and wanted to pop into autozone for them. Couple of miles up the road temp gauge hit the red so I pulled over and took a look. The top hose was sucked flat! Never seen that before - any ideas?

Well let it cool and opened up radiator cap- A little vacuum but liquid level ok. Hose back to normal shape. Put cap back on and continued to go for parts. Temp stayed in the middle of the gauge to a little bit below. Heat gave good heat on low fan but if i put fan on full it goes cold still. I am now thinking it might be a flap inside the truck. O bye the way the water in and out of heater is hot and not quite so hot respectively, valve checked out fine.

Sorry this wa long - keep suggestions comming please

the_supernerd

Check that the heater control valve on the firewall works. Set the heater control to cold and see where the arm on the valve is at. Set it to hot and see where it is at. If it stays in the same position then the cable is broken. If the control valve is stuck closed then it would cause the heater to be warm when on low and cold when on high. A bad heater core could also be the cause.

You might also have an air bubble, which would explain why the engine started to overheat. Make sure that you have the correct radiator cap and that the overflow tank hose is not clogged. The system should have sucked in coolant (or air if it is empty) from the overflow tank instead of sucking the upper radiator hose flat.