Water temperature fluctuation

[tch81]

hi guys,looking for some help with a problem I'm having with my '03 520i. I recently changed the 2 plastic top radiator tanks (left and right of the radiator) as they were leaking slightly. there were no problems with the water temperature they were leaking.after changing the tanks, the water temperature goes up from 1/2 way to 3/4 after driving for about 10 minutes. it then goes back down again and doesn't go up for the rest of the journey. it happens when the car is both stationary or moving.any suggestions on what might be the problem?thanks for your help.

 

[jarance]

did you mechanic bleed the cooling system properly?

 

[tch81]

hi jarance,

I'm not sure about that. I'll go and double check with him. thanks!

 

[jarance]

pls do a search on "temperature" in the E39 thread.

Sometime airlock in the cooling system will cause the temperature fluctuation. If you have not have this problem prior to the changing of the expansion tank, then it is most likely air trap in the cooling system.

However, if you have this problem before you change the expansion tank, then your problem could be due to the aux fan or the fan clutch. Another possibility that you could ask your mechanic to check is the thermostat, water temperature sensor and the water pump.

Just be careful with the temperature. When it exceed more than 3/4, your engine might overheat.

 

[deep3102]

its probably an airlock, like jarance mentioned. Remember my mech telling me these symptoms if bleeding not done properly. Get it checked.

cheers~

 

[mick123]

happened to me just 2 days after collecting the car from the previous owner. first the aircon fan gave way which caused the temp to fluctuate. got that fixed and 2 days later, the temp suddenly went up slowly while coming back from klia. sent it in and found that the head gasket is gone. so with the engine striped down, found the radiator, fan clutch (quite worned out) and thermostat not in good condition. there was some whitish sludge on the hoses and possibly also partly choked up the radiator. according to my mechanic, this was due to the use of too much coolant. so changed basically the whole cooling system for a better peace of mind.

but then, as i'm new to bmw, this morning when i checked the water level, it dropped a bit after 2 weeks of driving and i added about 200ml of water. this is normal according to my mechanic. do you guys experience this? anyway, he advised me to properly bleed after refilling and never to refill when the car is still hot.

 

[jarance]

mick, it not normal to add water. There should not not be any lost of water. There are some leak if you need to top up the water for the radiator.

I dont there is such thing as too much coolant. It is more often due to expired coolant.

 

[bimmer73]

hi jarance,

I'm not sure about that. I'll go and double check with him. thanks!

Bro DO NOT DRIVE YOU CAR WHEN TEMPRETURE IS UP even slightly pass the halfway mark. You engine won't just over heat it will crack your cylinder head and will cost you your engine.

 

[jaleeks23]

the understanding that i have about original BMW coolant, the colour will go off after some time. So, during service, when top-up water, at the bleeding nut, need to see if still got coolant colour, if not, means no more coolant means need to add coolant. Is my understanding correct?

I thought those deposit is due to wrong type of coolant used? non-ori bmw coolant?

 

[macgy]

Water level in E39 in measure by the float, the float should finally settled at the level of the radiator cap / the neck when engine is cold, u know that don't u?
if the float drop below that level, something is wrong, u have to investigate asap.
does the engine warning light came on when the car overheat? 1st thing to do is bleed the radiator properly and see if the problem remain.

 

[bimmer73]

hi guys,

looking for some help with a problem I'm having with my '03 520i. I recently changed the 2 plastic top radiator tanks (left and right of the radiator) as they were leaking slightly. there were no problems with the water temperature they were leaking.

after changing the tanks, the water temperature goes up from 1/2 way to 3/4 after driving for about 10 minutes. it then goes back down again and doesn't go up for the rest of the journey. it happens when the car is both stationary or moving.

any suggestions on what might be the problem?

thanks for your help.

with your engine off when it is hot check your water tubes press them to see if they are pressurise ( Hard). if they are then you have a problem with the cooling system. there is another PVC pipe that is located at the back of the engine. it may be worn and the thermostat is not functioning cause there is a leak somewhere. It happen to me th\e same as you have described. get it checked

 

[bmw7833]

Hi all, Naidu is a good person to rectify and solve the fluctuation problem?

 

[macgy]

if problem remain after proper bleeding, it is the thermostat, what brand is ur thermostat?

 

[lwloh]

i had my coolant changed 3 weeks ago. ever since then, i notice the electric fan turns on to max speed quite often. But the water temp maintained at half mark. ie. middle. Until i went up to Genting last week. On a few occasions when the car is stationary, the water temp needle slowly goes up to the white mark on the right and comes back down again as fast as it went up. at this point the fans are at max speed trying to cool the engine. I suspected air lock in the system, bleed the radiator myself this morning for 15 mins ! So far, i don't hear the fan being noisy now. Check the coolant temp while driving at night, around 85-95C. Idling at 87C. Outside temp shown 27.5C on the OBC. By the way, any one knwos what is the normal operating temp of radiator coolant ?

 

[haywire]

The coolant temperatures you've posted sounds about right. When I had my problems with the expansion tank the temperature hovers from 87-95C (from OBC Test Nr. 7) and the needle shows middle mark, and the when the temp reaches 110C the temperature needle shows at max/rightmost position.