mx5cartalk.com

Well,
less than a month ago my car overheated, and the radiator was empty all of a sudden. Steamed the poor chick serving me at the McDonalds drivethru.

Replaced thermostat and rad cap, didn't help. Radiator was old and brown, so I replaced that, but in the end it was a leaky little coolant hose that was spraying onto a hot part of the engine, and only leaking at high temps, so it wasn't leaving any pee puddles under the car.

Essentially the car has a new radiator, cap, thermostat, hoses and fluid. Drove it without issue for about a month then, as of these few warmer days, the car is overheating. Interestingly enough, it only overheats when I am NOT revving the crap out of her. Stopped at lights for a while, noticed the needle at far right, panicked, turned it off, and gently drove through the lights, and pulled into a side street. As I parked, I noticed the gauge was back to normal, but then started climbing back up pretty quickly. Confused, I put my foot down and noticed the faster I was going, the cooler the car got.

Did a little test and rolled down a loooong hill at about 80kmph in neutral. Gauge went to far right again. Dropped into 4th and kept the revs up around 4k, and the temp dropped again.

Fans are running fine.

Reckon a thermostat can break in 3 weeks? I've heard of them being faulty out of the packet, but can a good one go bad in 3 weeks?!

the thermostas is one thing.....the sensor thingy above that is another. The water sensor.

bugger...you drive a NB8A....not an NA6....duh!!!

Sounds like its water pump related.

Could be the thermostat they are notoriously unpredictable regarding reliability.

You need to just go through the system, check the radiator is flowing well, check the engine block is flowing well, check the belt is on the pump tight, check the pump flows the water well, check the thermostat works with boiling water.

Etc etc etc

it's really the only way to get the whole thing spot on and guarantee you find it.



Dann

sounds like old water pump to me. normally water pump goes a few weeks after a complete flush. and the rust and mud and other crap somehow hold it all together. then add new fluid, and it's dead within the month.

as dann sadi, check those things also. but i'm pretty certain with the symtoms your are having, the pump is near dead. probably missing a few fins.

sounds like a engine thread for the engine section.

water pump is only 30,000k old.

or else an airflow problem. Do you still have the engine pan fitted? Does the radiator fit reasonably flush with the surrounding bodywork? The radiator should be clean because it's new but is the A/C condenser in front of it blocked with bugs.

Everything inside the engine bay is stock and OEM parts except for the timing wheel.

The problem seems to be intermittent, Can thermostats seize partially, and only cause problems some of the time?