Major Cooling Issue.......1999 Tacoma 2.7 4X4 SR5

thats what I thought too, but all the u tube videos I run into claim that the temp sensors is in the back of the engine on the 99. My shop manual doesn't show anything for that side of the cooling system.

 

Like I said, not a Toyota expert, but I work for at a Ford dealership, and there are split year vehicles that have minor differences like that. Maybe that's the case with yours.

 

After replacing the new radiator, how much coolant did you put back in?

And how much was in radiator when rechecking after getting hot?

This very much does sound like a 'burping' incident because steam (and only steam) is what is being read by the sensor when it is in the dry.

These trucks aren't terrible about having to be burped, but after taking off so many parts, it's easy for the block to be empty (air) and then after putting in a new thermostat, the block is pretty much airtight from filling up until that thermostat opens for air to escape. It doesn't like to when it's dry itself, sometimes the 'jiggle valve' takes care of it, sometimes not.

Most cars (without bleeder screws) I let warm slowly with no cap 'til they burp and i see coolant moving around OR fill let it get to temp with the cap on , then kill it and let cool, then recheck.

If you shut it down right after seeing it spike, I doubt you did damage but it SHOULD be needing quite a bit more coolant now. If so, it was an air pocket......you gotta watch 'em close for a day or so after a radiator pull out, making sure that overflow stays with enough to keep filling as air makes it's way out.

 

Generally, boiling water means 1 thing. Not enough pressure in the system. Your hoses haven't blown so that's not the issue, and they will blow (or crack/leak) when they've gone bad. Change them if you want. This could be from a faulty radiator cap or an air pocket. If you haven't changed your cap, do it. It's not an expensive part. If you haven't burped your system, park it on as steep of an incline as you can (forward facing up) turn the heater all the way on, and run the truck for a bit. Once it cools down, check the coolant level, fill if need be, repeat until coolant seems filled to the top of the radiator at the cap.

 

Did you install the thermostat backwards?

 

I'm going to say it's a bad head gasket....wanna bet?
Coolant boiling? Nah more lie combustion gasses bubbling up.

 

I guess I will try a new rad cap and "burp" the system thoroughly. The level did go down extremely low after I did shut it off. As for the gases.....these were not bubbles, this was a full boil going on.

 

It's kind of messy, but you can run it with the rad cap off and heater on to "burp" it. it may help to jack up the front end to try to lift your fill point higher of that makes any sense. Or you can get a professional tool like an airlift which pulls a vacuum inside the cooling system and then sucks the coolant in.

 

If the level went down extremely low after the spike, you had a giant air bubble.

I'm betting your ok now. These things are pretty tough for 1 time overheat.

Prob. a good idea to put a new cap w/ new radiator and give it another try.

You MAY be able to get that connector to reconnect but really the snap part of the harness is what crumbled. Those can be ordered or you can insulate it w/ tape if just trying to sell. Your call. Will look a little 'unmaintained' just plugged in since it's kind of right out in the middle of Broadway like that.

FWIW, I do wish all vehicles had a bleeder plug right above the thermostat. Sure would cut down on these scares. I had it happen to an expensive engine once and was really dreading the next start.

 

If your level went down after it shut off, im now almost 100% certain it wasn't burped right. And I'm not accusing you of anything bad when I say that. That's because burping a system is kind of an advance knowledge skill regarding radiator swaps.

Also, if there was a bad head gasket, the overflow tank would be, well, overflowing because the excess air from the cylinders pushes coolant out of the system and the only place it can go. The overflow tank.

You're doing well, brother. just make sure it's got enough coolant and you will be fine.

 

i dont recommend using str8 water as a coolant.