intermittent coolant low warning light

[valkryie]

Hi Guys,Need some advice on my E46 N42 @ 70K kms. My coolant warning light comes on for 5 seconds and then goes away. This problem has been happenning for more than half a year and it happens intermittently when the car is going fast on the highways. Check the water level the next morning with engine cold. The dipstick in sticking up and water can be seen clearly in the neck of the expansion tank. Already did 4 checks with 4 different mechanics but none can convince me that they have nailed the problem down. All 4 mechanics did high pressure test but did not find any leaks. AB (the 1st shop) did a check in the morning and found no leak but in the next morning (left the car overnight with them) did another check and told me the expansion tank is leaking and want to charge me RM 700 but I don't believe them. Water is still in my tank. The last 3 shops did a pressure test on a hot engine. 2nd shop change my cap and put in a new bottle coolant. 3rd and 4th shop recommend replacing expansion tank.I am in the opinion that changing the expansion tank will not solve this problem if the current tank is not leaking and there is enough water in the tank. What could the problem be? How does the OBC know that the coolant level is low? It seems there is no electrical connection to the expansion tank other than a thermostat but I could be wrong. Thanks for the input.

 

[conan]

try bleeding the radiator. it solved a similar problem i had with the low coolant warning....

 

[GREEN KILLER]

Yes, try as Conan says.

 

[conan]

just a word of advice if u intend to DIY. i tried DIY-ing and made the matter worse... in the end had to ask AB to do it. :blush:

 

[valkryie]

OK, thanks for the input.

I had the expansion tank changed and the radiator flush and refill. Hope it will solve my problem.

Me pretty sceptical with auto mechanics nowadays after AB over charged me for engine oil and quoted me RM 700-00 for expansion tank "leak".

 

[Zoggee]

haiyo....I was about to Kepoche here.

Why change the radiator..???? check ur coolant sensor ma. always happens wan.

want Zodic wifi..???

 

[lass 18]

Just heard from a mech 2day. The coolant sensor could be the culprit.

Was with a mech 2day 2 replace tensioner bearing. The mech noticed coolant residue on the expansion tank and when checked discovered valve broken. Advised changing the expansion tank as this could result in engine overheating. He also replaced the coolant sensor as the sensor was cracked at a few locations (I presume due to heat) and informed me not to be surprised if coolant warning light activates intermittently even after replacing the damaged sensor with a new sensor. It seems that this is quite a common problem with the e36. Not sure about the e46 though.

The price 4 the coolant sensor the workshop charged me was RM75 (excluding labor). The workshop bought the coolant sensor from Bavarian Auto. Saw a delivery boy in Bavarian Auto T Shirt delivering the sensor.

 

[lass 18]

Ooops. The water tank for the e36, the workshop charged me RM195 (part only excluding labor).

 

[valkryie]

Hi Zogee,

I did raise the coolant sensor point to the last 2 workshops but both recommended expansion tank change citing the following reasons:

The reason they say is that the tank is due for change otherwise the tank can crack due to it being brittle over time and heat stress.

One of the workshops says he is quite confident that the main culprit is the sensor in the expansion tank itself and not the external sensor at the bottom of the tank.

Anyway I thought I might as well change the expansion tank. It is cheap insurance against possible future overheating problems as recommended in www.edgemotorworks.com. I give him the benefit of the doubt since he can make more money by recommending tank plus a sensor change but only recommended changing the tank.

I can always change the sensor later on if the problem does not get resolve. I have to drive faster on the highway now and see if the problem will happen again

 

[valkryie]

This just came to my mind. Maybe the real culprit to this coolant low warning is my fast driving? The light only come on when i drive fast and after 2-5 seconds goes off by itself because i slow down. Scared overheat.

The car tends to dive/bounce and lean too much at high speed on the KLIA highway maybe causing lots of water movement.

Time to change shock absorbers more $$$$ :beaten:

 

[conan]

so the problem has been resolved with the change of the tank?

 

[valkryie]

Hi Conan,

Not sure yet. But so far the warning light has not light up when driving along NKVE.

Will have to monitor closely. If the coolant light lit up again then will get the sensor replaced.

 

[han8]

maybe the warning light would not light up at NKVE , try at chowkiat or bukit bintang area, sure light up............. :rofl:
(just to cool down the unease situation here)










http://www.abangpower.com/?ref=ManForever

 

[ess530i]

i am facing the same problem with my e60...coolant level low warning comes on intermittently especially during high speed driving.

conan, how do u bleed the radiator? my mechanic will be doing it but just wanna make sure he does it right. and what is the best recommendation as radiator fluid? thx..