3vze over heating

[iam_turner]

Hello,
Just bought the 90 Runner.
Before it sat for the winter (the last 5 monts) the head gaskets were changed, along with the thermostatt.

Before replacing the thermostatt it was over heating, however after the new thermostatt was installed the problem seemed to disapear.

Started it up today and drove it for a few kilometers and it started to overheat. I shut it off and let it cool down for a while. Checked the coolant and it was down about half a litre. I filled the coolant (in the rad and to the cool line in the resevoir). Tried again.

Started it up and drove it for a little while, the same thing happened.

I let it cool, and started it up again, and tried driving around with the heater on full heat and full blower. It did not over heat at all.

Any ideas of what the problem might be?

 

[IBCRUSN]

It may have been down a half litre just from purging the air from the t-stat replacement. Does your exhaust have any white smoke? Have you checked your oil level recently? One thing I have noticed as nearly universal is most shops totally ignore the fan clutch when looking at the cooling system. If you can't ascertain the history of your fan clutch either replace it with new or disassemble, clean and re-service it with fresh silicone fluid (5000 cst or better depending on your location).

 

[iam_turner]

There does not seem to be any white smoke. I never thought about the fan clutch - don't really know anything about it.

It's really weird because it can idle fine with the blower on max and heat on max, but if I turn either of those down it over heats.

I think something's wrong with the thermostat, or else something is plugging up the rad...

 

[ms018kmf]

X2 on the fan clutch, there's a quick way to check it. Pop the hood and get a piece of cardboard. If you can stop the fan with the cardboard (careful, watch those eyes and digits) the clutch is finished. When mine went I could stop the fan and it would take a minute to spool back up to the idle speed.

 

[2ndGenToyotaFan]

Try the above test when the engine is warmed up.

 

[Arivalsend]

How many miles on the engine, was the water pump replaced or is it original? I would also check out your radiator and make sure your fluids are topped off. As was stated before it pays as many times you are low and just don't know it. Any fluid loss? Fan clutch is a good idea, but depending on the age I would say that it may be fine. Also if the fan clutch is not working it would still cool down at speed on the highway. Regardless of the fan clutch. One other thing to try would be either a full fluid flush to pull out the air. Or just start it and run it with the radiator cap off and see if you have any bubbles coming up through the fluid.

 

[iam_turner]

There are 176 K on the truck - the head gaskets were just changed this past summer. The coolant level was fine as I topped it up. I havn't checked the fan clutch yet. I thought there may have been something in the coolant plugging up the thermostat, so tonight I flushed out the rad twice using some water/air, and I removed the thermostat...

But now it's acting really strange. When I turn it on it does not idle properly fluctuating between 2000 RPM and 1500.

After filling up the rad as much as I could I put the rad cap on and turned the truck on, then topping up the coolant. I tried to let it idle for a while but it kept running funny (as mentioned above) and so I checked the coolant, it was all foaming and bubbly. I hope this does not mean what I fear? Bad head, or gaskets were not installed correctly?

Is it normal for coolant to be bubbly for the first while, after just flushing the rad?
PS - thanks for all the help people, I do appreciate it.