ZED_NOT_ZEE
Member
Wasn't expecting this coolant system to require so much work!!!
A few months ago I was on the highway and the low coolant light came on. So I drove the car to my destination slowly making sure the engine temp needle didn't rise. Let the car cool, and filled it back up.
Drove home, and next morning there was coolant on the floor under the car. But then the car drove fine for a good 3-4 weeks until the light came on again. Filled it up, and leaks immediately afterwards... then stops and is fine for another 3-4 weeks.
So I figured it must be a crack near the top of the expansion tank. Happens a lot with these cars, had to replace the coolant expansion tank on my e46 too. Not a big deal, since the crack is not at the bottom of the tank. (not all the coolant leaks out, only some of it right after I fill it up.)
So today I finally have a chance to tackle this project.
I do a compression test on the coolant system and the expansion tank is pissing coolant from the top seam close to the rad cap.
So I drive to my parts supplier, get a new expansion tank, and replace it.
All done, right? Wrong. Once she's filled up, I do another compression test to make sure I plugged everything together properly.
But a new leak shows up, from the water pump this time! The weeping hole is dripping coolant now.
So back to the parts guy, pick up a new water pump, and start replacing it. BMW made this pump extremely difficult to replace! On a 330i with a smaller engine bay (but same engine) it's so simple, 15 minute job from under the car. On the Z4 3.0i there is a huge metal brace between the radiator and the engine, exactly where the bolts are to access / remove the water pump. So the whole engine has to come off the engine mounts, and have to lift the engine out of the car a few inches to access the pump!
So, the new water pump is replaced, coolant filled & bled, all is good, right? Do another compression test and...
A THIRD LEAK. This time from the thermostat.
Back to the parts shop, get a t-stat, replace that and...
ALL FIXED! Finally.
Replacing those 3 parts with OEM, one of my e-brakes was not disengaging after sitting over night so I had to replace the spring lift. Car got an oil change, cleaned the contacts on the parking lights in the rear bumper (one of them was not working), and replaced one of the cup holders.
My total bill came up to $600 CDN (around 430 euros) and a good 5 hours of time. I think next time I'll take this car to an indy shop... Z4's are not as easy to work on as other bimmers. :/
A few months ago I was on the highway and the low coolant light came on. So I drove the car to my destination slowly making sure the engine temp needle didn't rise. Let the car cool, and filled it back up.
Drove home, and next morning there was coolant on the floor under the car. But then the car drove fine for a good 3-4 weeks until the light came on again. Filled it up, and leaks immediately afterwards... then stops and is fine for another 3-4 weeks.
So I figured it must be a crack near the top of the expansion tank. Happens a lot with these cars, had to replace the coolant expansion tank on my e46 too. Not a big deal, since the crack is not at the bottom of the tank. (not all the coolant leaks out, only some of it right after I fill it up.)
So today I finally have a chance to tackle this project.
I do a compression test on the coolant system and the expansion tank is pissing coolant from the top seam close to the rad cap.
So I drive to my parts supplier, get a new expansion tank, and replace it.
All done, right? Wrong. Once she's filled up, I do another compression test to make sure I plugged everything together properly.
But a new leak shows up, from the water pump this time! The weeping hole is dripping coolant now.
So back to the parts guy, pick up a new water pump, and start replacing it. BMW made this pump extremely difficult to replace! On a 330i with a smaller engine bay (but same engine) it's so simple, 15 minute job from under the car. On the Z4 3.0i there is a huge metal brace between the radiator and the engine, exactly where the bolts are to access / remove the water pump. So the whole engine has to come off the engine mounts, and have to lift the engine out of the car a few inches to access the pump!
So, the new water pump is replaced, coolant filled & bled, all is good, right? Do another compression test and...
A THIRD LEAK. This time from the thermostat.
Back to the parts shop, get a t-stat, replace that and...
ALL FIXED! Finally.
Replacing those 3 parts with OEM, one of my e-brakes was not disengaging after sitting over night so I had to replace the spring lift. Car got an oil change, cleaned the contacts on the parking lights in the rear bumper (one of them was not working), and replaced one of the cup holders.
My total bill came up to $600 CDN (around 430 euros) and a good 5 hours of time. I think next time I'll take this car to an indy shop... Z4's are not as easy to work on as other bimmers. :/
