Tacoma 2.7 overheating+heat not working

The truck overheated several months ago and I pulled over and filled back up with coolant and drove and it stopped.them it did it again the other day and I filled back with coolant and it was fine for a day or two until it overheated again filled coolant back up and was fine . Now it does this every few days and I am unable to see a leak anywhere.the heat also blows cold air where should I start

 

I'm not sure about your leak problem but the cold air sounds like your thermostat may be sticking. Be sure to check your radiator, upper, and lower hose for any cracks. Put a piece of cardboard or something under your engine over night if you have to.

 

Given these facts, I think it is safe to say that it is leaking somewhere, and that is causing your overheating problems. I would give some liquid radiator sealant a try if it isn't apparent. If it isn't leaving puddles where you park I wonder if it only leaks when it is under pressure, which could happen with a cracked hose or something of that sort.

Have you changed your oil since you originally had the problem? Could be the hellish possibility that you are losing it into your oil.

 

You could also be loosing it through your head gasket into your exhaust etc. If you change or check your oil and it is milky... that is where your coolant is.

 

Could be a leak directly in the radiator core. Thats where my last leak was. It left no puddles even parked because it only came out once it was pressurized. On top of that, it was near the top of the radiator core and the heat was causing the coolant to evaporate before it reached the ground.

 

Is there air in your system?

As stated above, make sure your thermostat is ok. Never a bad thing to replace if you are of higher mileage.

 

With no evidence of a leak anywhere and it keeps overheating and is low on coolant... It is either going into the engine oil, the transmission ( if it is an automatic ) or into the cylinder and out the exhaust. From your description is sounds like it is getting worse.

Check the oil if it is milky it is probably a blown head gasket leaking coolant into the oil passage(s).

Check the transmission fluid ( if it has an automatic transmission ), if it is milky the radiator is defective passing coolant into the transmission fluid heat exchanger coil.

If none of these are true, you have a blown head gasket leaking into the cylinder more than likely. Sort of rare on the 2.7L engine.

 

Had a pinhole in the rear fins that would not show any visible leaking while running. Essentially the fan blew the tiny stream away. Took weeks to find, but had similar symptoms. BTW radiator is $300+.

 

I am about to change the oil

 

Thanks for all the feedback !!I got it fixed yesterday . I changed the thermostat and flushed the radiator

 

Hello! Did you fix that problem permanently with the thermostat and the flush???