Running Hot

[supra_chick_1987]

I have a 1987 automatic non turbo Supra...in pretty good condition. I've done a lot of work on it, but I'm stuck. Whenever i drive it hard (like on the freeway), then shut off the engine, I can hear it boiling. The temperature gauge says it's not overheated or even running hot, but you can hear it boiling. Upon recommendation by my mechanic, I've replaced the water pump, the thermostat, and the fan clutch. This seems to have corrected the problem of it overheating, but you can still hear it boiling. What should I do next? I've never run across this problem before!

[suprasabre]

Is your heater working? If not you might be hearing the noise coming from air trapped in the heater core?

After replacing my water pump, I couldn't get the heater working, so I took the car out on the street put it in reverse and hit the brakes hard. Did this maybe four times and heat started flowing in.

[supra_chick_1987]

the heat is working just fine....i have not had to replace the heater, and i have actually used it to help cool down the car when it has overheated in the past.

[supramacist]

Is it boiling or bubbling you hear?
Do you hear a water fall type noise?
Is your low coolant or bird cage light coming on through hard corners?

If any of this doesn't sound foreighn to you.

You may just need to burp the beast and top it off.

Elevate the nose of the car as high as you can. Pull the rad cap off and watch for bubbles.

This process takes a while. Keep topping it off and keep watching for bubbles.

Crank the engine over a few times but don't start it. This will circulate the bubble inside the coolant system if you have one.

Eventually the bubbles will stop. Top it off 1 last time. And repeat every now and again.

That's if these are also your symptoms.

Hope this helps.

[supra_chick_1987]

It sounds like bubbles, but it's rapid....like when you boil water on the stove over really high heat. I've seen it before (before I replaced the water pump), and it was bubbling and rocking back and forth....kinda odd, lol.

As far as the "birdcage" light, (add engine coolant) it came on about a year ago, and I bought more coolant, but my mechanic said that it was full, and simply unplugged the sensor. He said that the sensors sometimes go out, and will tell you that you need to add stuff when you really don't.

[mkiiisupra]

plug that sensor back in lol

Anyways it doesnt measure the amount of coolant in your system just the amount of coolant in the overflow tank.

So when ur Raditor pulls collant out of the overflow due to a leak somewhere it gets low and thowrs the birdcage at you

[mkiiisupra]

When i had a blown head gasket my engine would do this. Coolant wouldnt flow properly through the engine, it would just sit in the bottom of it and boil

[weol66]

i have the same problem with mine when i drive no problem only when i shut it down i heard bubbling when i poped the hood noticed overflow boiling,head gasket

[sd88supra]

I had the same problem, but I did the following and it went away:

- Check the headgasket and make sure its ok. Running with a hot engine will increase your chance of blowing the headgasket.

- "burp" the system and top it off just how others have described.

- Look for any pinched or damaged hoses. If there's pressure leaking it won't allow the coolant to flow efficiently. If a hose is pinched it can cause the pressure to rise and your cap might not be able to hold it, and you'll lose coolant.

- get a new radiator cap from Toyota. Aftermarket caps usually fall between "accepted" ranges which sometimes aren't so acceptable, especially with Japan using the metric system and the US still living in the dark ages when making measurements. Once I got a new cap from Toyota my coolant loss stopped (I was afraid it was the headgasket!).

- you might not want to do this if you just replaced the fan clutch, but electric fans cool much more efficiently than fan clutches, especially during hot weather. They take some load off your engine as well. You don't have a turbo, so a $130 electric fan will do just fine, and your engine will thank you for it.

Hope this helps.

[sd88supra]

I forgot, it boils after you turn off the car because there's no more air flowing onto the engine nor is there coolant flow, so the coolant (and engine as well) heats up. A minute after turning the car off, put the key in the open position (but don't start the engine) and you'll see that the temp gauge will have gone up. Not a good thing. Your coolant should never boil.