Overheating Mystery

Just bought a Tacoma with a presumed blown head gasket or cracked head. It would overheat and was loosing coolant. No milky oil or oil in coolant. Assume it was going out exhaust. Dealership came up with this diagnosis after changing thermostat and flushing cooling system. Since then, I have replaced head gasket, got head redone, new water pump, and radiator. The only cooling component that hasn't been replaced is the fan clutch. After all this work and money spent, it is still running hot but it's not consistent. It seems to get hot when pulling a hill or getting on the throttle or at higher speeds. What could this be? I am completely stumped.

 

Pulling on a hill sounds like the fan clutch. It should engage as engine temps rise to keep it cool and is failing to do so.

 

Any more details about your truck? Which model year? which engine? 3.4L or 2.7L or 2.4L?

What method are you using to determine engine temps? Are you relying on the dash temp gauge for this info?

 

+1. I did a full rebuild on my 2000 and after the rebuild the dash gauge was showing it close to overheating. I put an aftermarket gauge in and it is showing a consistent 184-188 degree temp range (180 degree t-stat).

 

Would definitely look into clutch fan. Is it fine while driving (unless punching it or going over hills, as you said) but when stopped at a light, the temp climbs?

 

Time to upgrade to an electric fan? Flex-A-Lite makes some really good ones, I'm running a dual e-fan myself.

 

I did that when my fan clutch went out on a previous Toyota truck. I didn't really like it actually. It was noisy (sounded like a hair dryer at a stop light) and put a noticeable electrical load on the system as you can see the lights dim when it clicked on. Worked great and did its job well though.

 

True, I always found it funny that Flex a lite advertises their fans as being "quiet" but mine at least is anything but quiet, though I do think it's quieter than the clutch fan was. At least from the outside of the truck. Inside the cab, I can hear (and feel) it at idle like 'VOOM voom VOOM voom VOOM voom, etc.). It was kinda annoying at first, but I do like how well it keeps the motor cool especially when I'm offroading. I can definitely see its effect on pulling power off the battery when I'm a little too light on the clutch at night too, lol

Mine is actually manually operated from a switch I have in my cab, I leave it on 99% of the time but if I ever wanted to just let the cool outside air do it's job while moving on the highway for instance, I can shut the fans off.

Not that I can hear it when I'm driving anyway over the sound of the trd headers and supercharger

 

just wondering... your going after the clutch fan but I dont see mention of the radiator ever being replaced. just because its not leaking doesn't mean its not plugged.