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Discussion Starter #1 (Edited)
Installed a new radiator yesterday
install went fine .. as usual BMW made it easy .......


filled it with coolant and water 50/50
let it run for a bit .. seemed to be fine ...

coolant is at the prescribed level .

now the fun part begins ......... seems to run HOT ... gets near the red and then falls back below ..... then moves up IN the red and then falls back ....... some times runs dead in the middle of the guage .....then goes hot again ..
all this while driving about 60-80 MPH ........ penty of air getting through ....


my first thought is an air bubble in the system ... dont see the fluid level going down at all or leaking out any where ......... and there seemed to be plenty of fluid put in .... like over 2 gallons +


there deosnt seemd to be a bleed nipple to let the air OUT as in previous Bimmers Ive had . on the thermostate housing


is there a special way to BURP this baby ????:dunno:

HELP

dont want to melt it down....... :eek:oohhh:
 

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it strangely sounds like a thermostat problem.

i had a while ago almost the same kind off problems and for me it was the thermostat.mine was 1/4 stuck open , so when driving it overheated and when i stopped the the temp dropt back to optimal.when i went back on the road after 5minutes ,the same problem came back over and over again.

i dont know the exact bleeding procedure for a 540 radiator, but for the m5 its like , let the cold engine run with open radiator cap and fill up to max level.1 minute or so and then close the radiator and run the car warm .then let it cool down and check the radiator bottle . iff the level dropt ,do it all over again until its ok.
 

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Discussion Starter #3
thanks

I think you might be right ......... did some reading found that it seems to act like a dodgy thermostate ....AND here is a bleed right near the rad cap ..

MY 540 has an M5 radiator in it ..... the are the same except the core is thicker in the M5 and this is a direct replacement .....

the over flow bottle and shroud are different ...but the 540 ones work just fine ..... may upgrade those too .......

I went though the same procedure as you describe and thats what has me a bit worried .....

Ill try once more bleeding out the bleed on the radiator

then put in a new thermostate ......... kind of stange though as I replaced it just last year ..... would think it would last longer than that ........



thanks for the help
 

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I think you might be right ......... did some reading found that it seems to act like a dodgy thermostate ....AND here is a bleed right near the rad cap ..

MY 540 has an M5 radiator in it ..... the are the same except the core is thicker in the M5 and this is a direct replacement .....

the over flow bottle and shroud are different ...but the 540 ones work just fine ..... may upgrade those too .......

I went though the same procedure as you describe and thats what has me a bit worried .....

Ill try once more bleeding out the bleed on the radiator

then put in a new thermostate ......... kind of stange though as I replaced it just last year ..... would think it would last longer than that ........



thanks for the help

yeah i know it can sound strange that a 1 year old thermostat breaks, mine was even younger... it survived only 6 months and was replaced under warranty.

iff there is a bleedercap next to your filling hole then you just have to unscrew that and fill the radiator up and squeese the hoses a bit while you add some coolant in . coolant will come out off the bleedercap when the radiator is full. then it must be airbubble free.
 
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