Thanks for your never-ending support! The quick and precise answers and suggestions that you all provide is priceless in its worth. After the timing belt change ( I skipped the water pump, it looked fine during a visual inspection) I drove my toyota camry (v6) up the road to the park to see if the overheating problem once again arises. Sure enough, after about 10 minutes on the road, my needle starts climbing towards H again, so I pull over and pop the hood. The first thing I saw was my coolant reservoir laying askew in my engine compartment, then I noticed coolant spewing out of the radiator cap. I disconnected one of the hoses to burp all the steam out, refilled the coolant and started to drive home. Almost immediately my needle reached for the H, but since home was right down the hill I decided to risk it. At the top of the hill there is a stop light, at which I was at red and idling, watching the needle touching the H now and going into the red zone. I could hear a hissing sound from under the hood which sounded like the radiator cap again. On green I crested the hill and started downwards and almost instantly my needle fell into the normal operating temp. Once on level ground again and parking my car on my street, the needle again began ascending to the H...so my question is: 1. My thermostat has been removed, so ruling that out, what could cause this?
2. Is my car cooling on declines because the angle moves the coolant towards my radiator? 3. Why so much pressure under the radiator cap?

3 Answers 3


You may have developed an air bubble in the system, probably from the reservoir falling off, or from the mechanics not bleeding the cooling system after emptying it. There'll be a pocket of air in the system that's making the car overheat.

Does the car lose power when it's overheating?

  • well it kind of feels like its in low gear, you know that tight feeling? How do I bleed the system? From the radiator release valve? Commented Mar 24, 2016 at 5:03
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    I can't directly comment on Camry v6's, but some engines have a bleed screw on the head/intake plenum that releases air, though other cars which do not have this can be bled by opening the radiator cap (when the car is cool!!!!) and letting it idle, slowly pouring in coolant as it bubbles down and lets air out of the system. I'd have a look for a workshop manual (Haynes/gregories books are also good) and see what the bleed process for your car is. It's quite simple to do however. If it feels like you're losing power though, you may have already cooked the head or head gasket. :( Commented Mar 24, 2016 at 5:12
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    It's a good identifier of a dead head gasket to see white smoke coming out the back, you can also look at the coolant/oil for signs of mixing (milky/muddy oil or coolant). But, this isn't always the case, as sometimes a crack can split a water gallery but not mix it into the oil. Also sudden excessive increase in fuel usage is an indicator. Commented Mar 24, 2016 at 5:45
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    Thank you! Your answer led me to googling how to bleed cooling system Toyota, and during one of the steps, my overheat problem went away. It's just a temporary fix, but it seems that when I run the heater (after flushing and bleeding) during the drive, I hardly hit the halfway mark on my temp gauge... I tested this by driving almost 10 miles, during which at no point did I ever break the halfway mark. Commented Mar 24, 2016 at 8:44
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    That's really good to hear! Although I would pay close attention to your coolant levels. Each time you go for a drive, check the water before you go to see if it's losing any. Good luck with it! Commented Mar 24, 2016 at 8:59

Coolant temperature decreasing on the incline could well be because the engine generates much less heat going downhill, since it's not working as hard. This would give the cooling system a chance to bring the temperature down.

  • True, but idling raised the temp. I understand the wind factor too will cool the engine while going downhill... But it was just... Different. The way the needle was reacting to the decline was very abrupt, not the usual gradual descent. It went from right below H to a quarter the way above C in about five seconds Commented Mar 24, 2016 at 17:10

Of course the wáter pump "looks" fine. It always does, until the seal fails. or the bearing fails and takes the seal with it. You should always change the pump when you are at the timing componentes. After the overheatings you experienced, it won't be long for the pump to fail. I am pretty sure your problems didn't go away completely.

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    Welcome to the site. The does not appear to answer the original question. Instead, you seem to be commenting on the original symptoms.
    – Bob Cross
    Commented Jul 5, 2016 at 2:42

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