Hi, this overheating problem is bugging me. Car would randomly overheat once in a while in traffic, and after you give it a good thrash. The fan does work because I jump the plug and it works and the fan switch works as well. Only when it overheats the fan doesn't turn on.

My theory is the thermostat gets stuck closed sometimes and then when that happens the fan switch will not read the true temperature of the water since the flow is blocked off by the stuck thermostat. The thermostat was some cheapo replacement I bought a few months ago so i think the thermostat might be **** or doesn't flow enough.

Is my theory feasable?

I may have to go buy an OEM thermostat.

Cheers

 

check water pump to. jus change the thermostat and if it dont work oh well there cheap anyyways

 

that is definitely your thermostat. i recently had th same problem with my mini... i had the a/c on, and it just kept blowing warm air, and everytime i'd idle at a light or something for longer than about a minute and a half, my temp guage would rocket and i'd start to overheat until i started driving again.

when i first caught it, i checked the freon and it was empty so i changed that, but it continued happening. took it to the bmw dealership and sure enough it was a blocked thermostat. they replaced it, and i haven't had a problem since.

so i guess troubleshooting would work... maybe take a look if:

1) does your a/c work?
2) low on freon?
3) does the engine cool down if you start to run it after it overheats?

and i'm not sure about the fan.. maybe check the electric connections...

good luck

 

Helms!

Freon? thats the R12 for A/C, i didnt know that has something to do with the cooling system...

I think if the fan dont turn on at the max operating temp.. Its possible its the temp switch. If not, check your thermostat. Both parts are cheap.. ohhh, very easy to check the fan motor its self, put wires from the battery to the connection doesnt matter which side is positive or negative, its AC.

the test for the thermostat and switch is located at the HELMS manual

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Dr Miller &raquo;</TD></TR><TR><TD CLASS="quote">that is definitely your thermostat. i recently had th same problem with my mini... i had the a/c on, and it just kept blowing warm air, and everytime i'd idle at a light or something for longer than about a minute and a half, my temp guage would rocket and i'd start to overheat until i started driving again.

when i first caught it, i checked the freon and it was empty so i changed that, but it continued happening. took it to the bmw dealership and sure enough it was a blocked thermostat. they replaced it, and i haven't had a problem since.

so i guess troubleshooting would work... maybe take a look if:

1) does your a/c work?
2) low on freon?
3) does the engine cool down if you start to run it after it overheats?

and i'm not sure about the fan.. maybe check the electric connections...

good luck </TD></TR></TABLE>


Dude, your talking about air conditioning. This man is talking about his cooling system....

Anyways, replace the thermo switch. This is the sensor on the thermostat housing. Its a cheap part, (under 40$ from honda) and you should be good. As long as you tested and verified that your fan switch and fan are working. An easy way to test this is to jump the sensor wires with the proper voltage, (while unplugged from the sensor), and see if the fan turns on. If it does, replace the switch.

You may also want to try topping off, bleeding air out of your radiator/coolant system.

 

yea, you're definitely right. i was just tryin to help

but hey, he could have a problem with his a/c, too! haha, whatever it is, i hope you get it fixed man.

 

Let you car warm up fully and grab the lower radiator hose, if the hose is cold and your overheating change the thermostat if your hose is hot and your still overheating change the thermo switch.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fasthatchb18c1 &raquo;</TD></TR><TR><TD CLASS="quote">Let you car warm up fully and grab the lower radiator hose, if the hose is cold and your overheating change the thermostat if your hose is hot and your still overheating change the thermo switch.</TD></TR></TABLE>

Exactly what he said; the sensor/switch that turns the fan on is located downstream from the thermostat, so naturally, if the thermo sticks, the fan wount activate. Happend to me on the road, 25 minutes from home. I had to wire the fan to the battery to stay permantly on, blast the heater, and drive under 40 mph on I4 in august....in orlando, FL. Really sucked, and overheating was an issue. Anyway, thats my story,...good luck

 

Replaced it with OEM thermostat. No more probs! Even survived the dyno with no issues.

OEM
Aftermarket