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re New rad & refill

Discuss problems you have had or are having with your Z4
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w1ndsurfnut
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re New rad & refill

Post by w1ndsurfnut » Sat Jun 16, 2018 8:40 pm

Just replaced my radiator after it sprung a leak. Drained down the system but I could not get the engine block drain plug out. The access is terrible. Anyway put it all back together and only managed to get 6 litres of new coolant in. Online it says 10.5l .Cant believe there is 4.5 litres in the block and that none of it came out. Any thoughts. Anyone else done this recently.

RenoRaines
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re New rad & refill

Post by RenoRaines » Wed Jun 20, 2018 9:33 am

Just recently did this. If you have managed to put 6L in, you did a good drain. Make sure you get all air out. OProcedure posted on bimmer forums didn't work for me. It stated to put the ignition on - heat MAX - low fan - gas pedal to the floor for 10 seconds (engine is off of course :D ) and open the air vent screw on on the radiator tube. It should open the thermostat but it didn't. So I started the engine and poured coolant directly in the expansion tank. Adding coolant when the level dropped. Kept the vent screw open until I saw coolant pouring out. At the end I had to suck some of the coolant out of the tank, to get a proper level. But it works.
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mjennings23
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re New rad & refill

Post by mjennings23 » Wed Jun 20, 2018 10:08 am

The pedal to the floor thing is for facelift cars only, they have an electric pump and this activates vent mode on it. The pre-facelift have a belt driven pump so no such tricks.

My method was as so:


Raise front of car so bleed screw is highest point, and put a drain tray under the expansion tank.

Filled up with 5l of water, checked for leaks etc.

Went in the car, ignition on, fans on low and temperature setting to maximum.

Removed bleed screw, and added 5l of coolant to the tank slowly. A lot of fluid will end up coming out of the bleed screw, this is normal and why you use water and a drain pan. The idea is the constant pressure of fluid being added to the expansion tank forces any air bubbles round to the bleed screw.

Once I was happy no more air was coming out, and that I'd added the correct amount of coolant, I ran the engine at 2000rpm for a few minutes to warm it up (can be done with diagnostic software)

Took it for a drive once happy the temp was stable, then let it all cool down, rechecked the levels, all good.

This was 3 months ago and it's all been perfect since.

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