Overheating, temperature fluctuation

[silviamaniac]

My car has overheat issue. During idle, the temperature is just fine, but i take a long time to heat up (winter).

After taking it for a spin, the temperature will start to climb really high and weird things will happen.

Sometimes, the temperature will suddenly drop to normal level in 2 seconds after a while. Sometimes it will go up and little bit and come back down to normal. Sometimes, it will go up all the way.

I pulled out the thermostat in the car today, and put it into boiling water together with a new thermostat, both of them open and close without problem.

The car has had this problem after sitting for a while in the winter. What can it be? Thermostat? Waterpump? head gasket?

Please give some advice. Thanks

[The Mic]

Pull the radiator cap and start the engine. If radiator fluid begins to churn and bubble and splash out the top, and/or if you get bubbling noises in the overflow tank, then chances are you have an internal head gasket leak. Get it fixed immediately before it gets worse and you blow your motor. If not, then it's safe to say the radiator needs cleaned and flushed, along with the heater core, or worse yet a damaged water pump, but usually you encounter immediate and severly obvious problems if the pump is bad. Try flushing the radiator by draining it and using a garden hose through the top, then spray the hose through the radiator from the inside out to remove the junk stuck to the front.

[silviamaniac]

i put my hand on the hose that came out from the thermostat, it is not hot at all.

However, the hose that goes to radiator is real hot.

[metalsyth]

Sounds to me like a partially stopped up radiator or could be some trapped air in the radiator.

More than likely it will not hurt to flush the radiator.

[s13sr20chris]

flush it and bleed the air out. is the rad low on coolant?

[ddgsxr504]

SIMPLE FIX CUT AND DRY, REPLACE YOUR RADIATOR CAP, IT IS FAULTY, SAME THING HAPPEN TO ME 3 YEARS AGO, TEMP WOULD BE NORMAL THEN SKYROKET THEN COME BACK DOWN SO ON AND SO ON. AFTER REPLACEING EVERTYHING, THEMOSTAT, RADIATOR HOSES, COMPLETE FLUSH IT TURNED OUT TO BE RAD CAP. IF IT DOESN'T WORK PROPERLY THEN ALL THE COOLED WATER STAYS IN THE RADIATOR AND DOESN'T RETUN TO THE BLOCK. JUST REMEMBER THIS IF YOU EVER HAVE A PROBLEM START EASY, DON'T LET ANYONE ASSUME FOR YOU THAT IT IS THE HEAD GASKET OR WATER PUMP, IF ANY OF THOSE WERE TO GO YOU WILL KNOW!

[s13sr20chris]

rad cap is certainly a possibility. a faulty cap will not hinder water from reaching the engine.

[Spec-R]

what are the symptoms of a bad water pump???

[mygodrulz]

There are three possible water pump failures that I've seen. You can have the bearings go bad, the seal can fail and it will leak to the outside of the engine, or there is a rare occasion where the impellar will come lose on the shaft and spin freely. Keep in mind that after 20 some years in the automotive repair, I've only seen this once, but it is a possibility.

[mygodrulz]

Good luck, I've been fighting with my son's 1991 240 for about two weeks and I haven't found the solution. The only way that will allow coolant to flow is to remove the thermostat altogether.

[s13sr20chris]

i have seen an aftermarket water pump with the impeller on backwards. it overheated really bad.