Why is water level in radiator dropping after each trip to/from work and boiling too fast after change of head gasket? The engine overheated when i was driving along the highway. The car , a toyota chaser 98, had an overhaul 1 piston was changed, head gasket was replaced and retorqued later, head was faced. At first it was ok and the mechanics even took it for a test drive. After retorquing thats when i started noticing the overflow tank getting full above the max and the coolant bubbling. Oil dipstick shows no milky colour. Radiator was flushed. There are no obvious leakages. When i started the engine with the rad cap off this morning the water quickly overflowed. The thermostat was removed (mechanic said its unnecessary in hot climate). I now fear the problem is with the head gasket. Dont know if the radiator cap will give similar signs)

Haha, "thermostat not rewuired for hot climate". You drive a fuel injected vehicle, it needs to get to operating temperature to get the most mpg's and run the cleanest. Did the mechanic get you new head bolts when the head hasket was replaced? Why was it retourqued after a drive? There is a torque spec and procedure and none say drive the vehicle then torque to ??ft/lbs. I dont know what engine you have but toyota likes to use aluminum heads which are sensitive to jead bolt torque and typically use torque-to- yeild head bolts which arnt reuseable and shouldnt be touched after tightened especially when hot. How quickly does it overflow? Slow rise out of radiator or shoots out fast?

If your mechanic said the thermostat is "unnecessary in hot climate" you need another mechanic he is an idiot and/or just lied to get you away from him

I was just thinking the same thing lol. Does head gasket, gets cheap on thermostat. Most likely he is an old school mechanic, it worked on carburated engines. Once fuel injection came around that wasnt the case anymore and the engines need to get to operating temperature. Also in some cases the thermostat restricts the flow so the coolant doesnt flow so fast it never cools in the radiator, sounds stupid but it happens.

One of my cars was doing the same. I found that the coolant lines going to the throttle body were stopped up. (Someone had put stop leak in radiator) Big mistake. After replacing lines and flushing out the throttle body the problem went away. Not sure if this will apply to your car tho.

That right there dandy is why I hate anything that claims to "fix it in a can"..there is no magic formula to fix anything that you pour out of a bottle

Also Andrew that does not sound stupid at all..it makes perfect sense and I have known that for a long time ....by self made mistake(s)..the coolant does not stay in the radiator long enough to cool just as you said

Put he correct thermostat back in it and allso make sure the radiator cap is good. Radiator caps are pressure sensative

Bubbles in the coolant reservoir indicate a blown head gasket. The mechanic took the thermostat out to lower the temperature and hide the fact that they screwed up the job.

Bring to another machanic and have a pressure test ran on it. Also is there white smoke comeing out of the exghust?

Wonder if your machanic put the head gasket in the right side up?

I agree with tenspeed on the bubbles in the tank and the radiator boiling like that. It indicates pressure from the combustion chamber(s) going in to the cooling system from a head gasket blown out again ..or..like Ronc said, the gasket was put on wrong side up which will do the same thing. Then you can consider things like a warped head, you mentioned it was "faced" which if not done properly by an experienced, competent machinist will ruin the head

Thanks guys for the responses. I went to another mechanic who deals mainly with the cooling system and discovered that there were multiple issues at work, radiator cap was defective, radiator was not flushed properly (i could see thick black stuff coming out when he flushed it) , bubbles in the system contributed inefficient cooling. Dont know but his explanation made sense. Afterwards there was a dramatic change, engine's running smooth. There's no bubbling or overflowing. In a nutshell the 1st mechanic did a shoddy job, having promised to be thorough.@andrew initially it was a slow rise @ronc258 there was no white smoke @davidh25 the head was faced by a renowned company which specializes in that, it underwent pressure test and was said to be ok. I was getting chills 'cause im planning to sell the car this month. Lesson learnt: at least have an idea about a car problem before parting with cash. Will tell the mechanic to put the thermostat back.

@Tenspeed your explanation is scary, you mean it's more like sweeping dirt under the rag? I pray there wont be big problems later.

If there are no bubbles now that second mechanic did the trick..he is far more competent than your first one..I wouldn't worry about it cchisango, if the gasket was upside down or blown out it would still be boiling bubbles, one thing I don't understand in what you wrote is "contributed inefficient cooling"..the air will keep it from cooling properly, right? do I understand that? And do that: get the thermostat back. It's a necessary component

PS don't pay the dude a dime to put it back

after how much time Toyota crola 95 needs coolant??? means for example after 200km or 400km etc because i drove my car like 400km in one month and it finished all the coolant inside i just checked it last night

Your coolant should never just go away. It's suggested to change it around every 3-5 years. But if it's disappearing it's either burning it or leaking it. Both are bad.

My engine do not overheat but i am loosing water in the reservoir after a long trip

If there is a leak in the radiator, you experience that. Try to replace a radiator cap. Check water hoses if there is any leak.