lexus-is2

I've got a big issue with my IS250 on holiday and driving down and temp gauge started climbing higher than half way. I stopped and noticed steam coming and i could see coolant boiling in the expansion tank. I let the car cool down then checked everything but no leaks anywhere to be seen. Topped up coolant and tried to drive down slowly and within minutes the same thing started happening and the expansion bottle was empty again so called breakdown service. Been towed to a garage which won't be open til Monday now. But the breakdown guy said he suspects the thermostat. Water pump looks fine and apparently no signs of bad head gasket. After a few hours of waiting for the breakdown guy he suggested putting some water in and see how it goes and at this point it didn't overheat. So maybe a sticky thermostat? The leak was definitely coming from the expansion bottle which to me seemed like it was because the bottle was boiling.

Any ideas what this can be? I won't know anything til Monday now

Gville350

iTrader: (10)

First off, in a situation like the above you need to immediately turn on the heat FUL BLAST. Second, find a safe place to park to examine the engine bay. Boiling coolant in the overflow is usually a sign of a blown headgasket, but before you go pulling heads and such, there are means to check for a bad HG. Could have been a hang-up of the thermostat, but we don't hear about that happening too often on these motors. But as they age more, I guess it'll continue to happen more often. Definitely give the water pump a second glance too.

lexus-is2

Car is at the Garage so hopefully will get some news on Monday. It's a Toyota garage. Strange thing is after letting the car cool and re-topping up the problem kept coming back and eventually when the car sat for around 2hrs it didn't seem to do it again so seems very intermittent. The coolant was definitely leaking because it was boiling and overflowing out of the expansion Bottle, when I opened the hood I could hear the coolant boiling like a kettle in the bottle and steam was coming out of the overflow drain pipe.

whitebeast

iTrader: (5)

haven't heard this problem before. Good luck bro!!

Gville350

iTrader: (10)

I've had this problem before; but in another car. It came from headlift from boosting 23psi on a 1.6L Honda motor. Or simply put, a blown HG. Your reason, overheating; my reason, too much advanced timing on my tune causing pre-ignition this causing excessive cylinder pressures...aka headlift.

GL!

lexus-is2

Problem solved. The pressure valve within the radiator cap had broken off and fallen inside the coolant system. The garage dismantled the pipes and drained coolant to take off the broken spring like valve and then re-filled and put in a new cap. Now the temperature sits very nicely below the half way mark.

Because the radiator cap was faulty, the coolant system wasnt pressurizing and the cap wasnt able to hold pressure. The system needs pressure to increase the boiling point of the coolant. Because the pressure wasnt there, the coolant was boiling much earlier and overflowing out of the expansion tank.

From this experience, I would highly recommend inspecting this cap for those who have not done so for a while, specially if the cap is over 3 years. If there is corrosion on it then might be worth changing it coz mine corroded and broke off. Then again my cap is over 6 years old. Catching it early will save you the hassle and money required if it were to break like mine did.

Gville350

iTrader: (10)

The corrosion was probably from using tap water instead of distilled water. I'll have to check mine for the hell of it soon.

lexus-is2

I never used tap water, always the pink toyota super long life undiluted

Gville350

iTrader: (10)

^Have you been the only owner though? You've been using the right stuff.