canterm

Hello to all. I have a 1996 4 runner 3.4 4X4 and the temperature gauge sometimes will begin to climb and I need to add antifreeze.

The problem is that I cannot for the life of me find out why I am losing any fluid. How often I have to add fluid tends to depend on how much I drive, but I would say I have been adding about 1 gal every month 1000-1500 miles. I cannot find the leak. I have brought it to the mechanic and he replaced the radiator and pressure tested, which was ok then.

When I open the hood and run it I cannot see any leaks. I am wondering if my thermostat could be bad and only opens some of the time and when it does not open it causes a leak some how because I have noticed the bottom radiator house at the end (away from the radiator) to appear like it has leaked, but cannot confirm this for sure. The other weird thing is that when the car's temperature begins to climb, I can turn the heat on and it begins to fall again.

I currently have about 225k on the truck and this has been the only problem I have had. The radiator was replaced about 3 months ago and one year before that. Houses are all fairly new and I cannot even find a pin hole.

Any advice/thoughts on this would be greatly appreciated.

Thanks

Mike

mt_goat

Nothing weird about that, that is perfectly normal. The heater is like a mini radiator inside your truck that you can call into action by turning on the heater. The temp should drop with it on.

That's a lot of coolant loss, maybe you are boiling the coolant and it is spewing out while you drive? Usually with these Toyotas the dash gauge doesn't show hot until it is really hot. Any white smoke out the exhaust?

You've had a pressure test that showed good, so I'd suspect the fan clutch isn't spinning the fan like it should. They do fail and need replacing.

Also how old is your water pump?

If you have OBDII, get yourself a cheap scanner and monitor the engine temps with that while you drive to see better what's going on. Those dash gauges are basically a fancy idiot light.