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yet another coolant problem

2K views 23 replies 10 participants last post by  mohamedrani 
#1 ·
hey guys, I've changed the radiator and checked all hoses, but i keep missing coolant so fast and I've checked everywhere and kept the car idle for a while , didn't find any trace of coolant falling anywhere, then i took the car for about 2 hours driving around the city and when i got back , i found that the coolant dropped almost the half , the radiator and around the radiator are totally dry , this problem is getting into my nerves because i don't know where could

any ideas what can cause that problem ?
 
#2 ·
dropped by half...meaning in the expansion tank? have to task...are you sure the system was bled properly of air? might try doing a pressure test on the system. rotating parts like the water pump may work well at idle, but shaft wobble at higher rpm's make cause it to leak then.
 
#5 ·
Make sure you bled it properly. Then fill the expansion tank to the proper level. Monitor it over the next few days.

Maybe you didn't get it bled properly originally, but now you've gotten the air out. If the level stays constant you should be good.

Note that most people recommend servicing the entire cooling system at one time so you don't have to go back in and replace stuff piece-meal.
 
#6 ·
well that's what i did:

1-unscrewed the bolt on the thermostat cover
2-unscrewed the bolt near the expansion tank
3-started filling the radiator till the coolant came out of the bolt on the thermostat cover then closed it
4-kept filling till the coolant came out of the bolt near the expansion tank then closed it
5-put the key on position 2 and turned on the heater to the max with hot water for couple of minutes while the cap is off
6-closed the cap and switched off the heater and kept the car running idle till the temp got to the center

is there anything i'm missing ?
 
#7 ·
Leaking coolant usually leaves behind some telltale signs. Did you check the plastic undertray for wet coolant or dried residue? With no clear signs of a significant loss, and assuming it's bled completely, the pressure test is probably the next step. Hope it's not an internal leak.
 
#9 ·
Regarding you point number 5, it can take a lot longer than a couple of minutes, maybe 15-20.
If you filled so fluid comes out of the bleeder screws then your expansion tank will be full. You may have to remove some fluid again after the heating procedure so its at the top mark of the bobber or at the line on your expansion tank.
Then take it for a little drive, let it sit and cool down to ambient temp., then check the fluid level.
 
#11 · (Edited)
Off....heat on max, fan on lowest setting, you will hear some gurgling from the expansion tank opening, there may be a while between each hick-up and eventually you wont hear any movement from the water.
I basically followed answer number 4 here https://www.bimmerfest.com/forums/showthread.php?t=639145
In the Pelicanparts instructions you turn the engine on, let it heat up until the valve opens then shut down and cool car, I did not do that, except afterwards I took it for a small drive and parked it until the next morning.
Driving 500 km I loose maybe one cup of coolant, its pretty stable. You cannot trust the temp gauge in the dash, its buffered and doesnt show any value of interest really, you can use the cluster test function to get instant temp readout while you drive if you want to test it.
 
#12 ·
Off....
I basically followed answer number 4 here https://www.bimmerfest.com/forums/showthread.php?t=639145
In the Pelicanparts instructions you turn the engine on, let it heat up until the valve opens then shut down and cool car, I did not do that, except afterwards I took it for a small drive and parked it until the next morning.
Driving 500 km I loose maybe one cup of coolant, its pretty stable. You cannot trust the temp gauge in the dash, its buffered and doesnt show any value of interest really, you can use the cluster test function to get instant temp readout while you drive if you want to test it.
but wont that kill the battery ?
 
#15 ·
528iAut you're the man !

i did exactly what you did, and it worked like charm , i after bleeding , i went for a ride about 45 mns , and when i got back i checked the coolant from the out side ( sticked a flashlight to the expansion tank and the coolant glowed) , the coolant level remained the same before the ride

thanks for the amazing help))))
 
#16 ·
You have the expansion tank without a floating device? On my expansion tank there is only a line halfway up the tank which is the "Max" level indicator.
Just check the level tomorrow when car is cool.
 
#19 ·
Had the same problem with my 87 525. After replacing the overfill cap and sensor, checking all of the hoses, replacing the clamps on the new, large radiator hoses with new "german" clamps, we finally located the problem. My leak was in the hose connection from the overfill to the radiator. The hose end was recut and reattached and no more leaks! The whole process took over 4 months and it is nerve-wracking to see that coolant light come on without any visible leaks on the garage floor.
 
#22 ·
Plastic tubes

Check the tube coming out of the cylinder head right behind the oil filter housing, ther are 2 plastic tubes that should be replaced every 150k, you will need to remove the intake manifold, they are plastic and break, you cannot see the leak because they leak more when driving because they feed the heater circuit.
Best of luck!
 
#23 ·
Where's my Coolant

First thing I would do is go to an automotive supply store and buy a cooling system pressure test kit. That will tell you if there is a pressure leak somewhere. It could be an internal leak like a head gasket, but its too early to make that conclusion. Good Luck!
 
#24 ·
First thing I would do is go to an automotive supply store and buy a cooling system pressure test kit. That will tell you if there is a pressure leak somewhere. It could be an internal leak like a head gasket, but its too early to make that conclusion. Good Luck!
well, i think i had a stuck air problem after bleeding , the coolant level is stable, will monitor it couple of days and if it got low again, then i have to make a pressure test then )
 
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