ugh coolant leak

[rsutoratosu]

I think its the expansion tank. i saw some puke when i parked the car, in the front driver side of the car...

i'll need to inspect it some more.. besides the tank, anything there I should replace while i'm there.. 07 @ 75k

I couldn't find where the thermostat & water pump is on realoem

off fcp, you guys tihnk mahle is just as good as BMW ones ?
https://www.fcpeuro.com/BMW-parts/Z4...&b=10&d=700&v=

[unluky]

Good chance it is the expansion tank - they are very prone to breakage - been there done that. Read as many install how to's as you can. Seems straight forward, but I remember a few things causing a few tools to become airborne......LOL

I remember that press fit being TIGHT and getting it back in was a mother. I read a tip about using a tiny bit of vasoline or silicone and it went right in then. If only I had read that sooner.....MAKE SURE IT IS ALL THE WAY IN! Take the belly cover off so you can get under and look/work as it will make your life easier from the start. Not a terrible job, just like any BMW job - knowing the tricks in advance is everything.

Mahle makes good stuff - I have used their products a few times and have zero complaints.

Good luck!

[rsutoratosu]

yeah , theres some great video on you tube on this.. do you think i should replace the hoses as well ?

[deemo319]

Originally Posted by rsutoratosu

yeah , theres some great video on you tube on this.. do you think i should replace the hoses as well ?

Yes.

[Steeler]

Read up on how to refill and remove air from the system as well.

[WickedNy]

Originally Posted by dbarton62

Read up on how to refill and remove air from the system as well.

Correct me if I'm wrong but I believe there's a pressure release valve that's used to burp the system...I recall turning something to purge the air

[Steeler]

Possible.

OP notes an 07 but also 3.0i

[Efthreeoh]

Originally Posted by WickedNy

Correct me if I'm wrong but I believe there's a pressure release valve that's used to burp the system...I recall turning something to purge the air

You have a 2007 3.0si, which is the N52 in-line 6 that uses an electric water pump rather than the previous 3.0i, which had an M54 in-line 6 and used a belt driven pump.

The N52 has a different coolant bleeding procedure because of the electric pump. You bleed the coolant with the engine cold. Once the system is drained, the procedure is this:
- open the bleed screw on the coolant reservoir a few turns
- slowly fill the coolant reservoir with a 50/50 mix of BMW coolant and distilled
- when the bubbles stop flowing from the bleed screw and coolant starts to flow from the bleed screw, stop filling the coolant reservoir.
- close the bleed screw and close the reservoir cap. The bleed screw only needs to be seated, if you crank down on it thinking tighter is better, you'll snap off the screw head. It has an o-ring below the screw head so it only needs to seat.
- turn on the ignition but not start the engine, which means turn the engine to start with out pressing the clutch (manual trans) or brake (automatic)
- set the heating system manually to the highest temp setting and the fan on the lowest setting.
- press the gas pedal for just over 10 seconds, which will turn on the electric water pump and start the bleed procedure.
- the bleed procedure goes for 12 minutes. You'll hear the water pump working, it sounds like a mini clothes washing machine.
- once the water pump stops after 12 minutes, turn off the ignition and open the reservoir cap and top off the coolant.

[Efthreeoh]

Originally Posted by rsutoratosu

yeah , theres some great video on you tube on this.. do you think i should replace the hoses as well ?

At 8 years and 230,000 miles I did a complete hose replacement on my E90 with the N52. None of the hoses really needed replacement. However, its now been discovered the only hose that could be suspect on the N52 is the thermostat-to-cylinderhead hose. The weak link is the plastic fitting (i.e. hose bib) on the cylinderhead side of the hose. The plastic can get soft over time and eventually fail. There is an aluminum replacement for the plastic fitting. You can get the fitting on e-bay or Amazon, there are several suppliers of it. I wrote a DIY to replace it for the N52 in the E90 (same engine). You can use that DIY to fit a new hose bib on the N52 in the Z4.

At 370,000 miles or so I decided to replace the t-stat hose bib with the aluminum replacement. So the hose had 150,000 miles and 6 years on it. I found the plastic was soft, but not ready to fail. But if you have the coolant drained, that is the time to replace the hose bib. I have the aluminum hose bib to replace the one on my Z4, I've just not gotten around to it yet. It could be that this is where your engine is leaking rather than the coolant reservoir.

https://www.e90post.com/forums/showthread.php?t=1618232

[rsutoratosu]

I just saw a video on the hose bib lol.. I did the coolant job many times.. ordering parts is another issue, figuring out what to get lol

[rsutoratosu]

So I got the top hoses off, having issue removing the expansion tank off the radiator.. supposedly its only held on to by tubes from bottom up. I didn't see any other screw on the expansion tank itself.. need to find more info on it..

fan's removed, so have clear view of everything

[rsutoratosu]

Got everything out.. the expansion tank actually doesn't look crack.. i order a pressure test kit.. after putting everything back, I want to test it to see if its leaking from other places.. that'll be this weekend.. was so hot over weekend, was unbearable working outside

[rsutoratosu]

Found the source, little hole in the tank.. I end up replacing all the hoses in green. The hoses were cheap enough that it was easier to replace than salvage. Also the upper and lower radiator hose was a pain to get in and out.. I used a trigger clamp to help me push it in.

I also got a pressure test kit as I got 3 other cars and having an universal one that works will help. Once i have it all back Ill do a test to make sure all the hoses are good.

I can see why we replace the belts and tensioner at the same time. I have both ready but no t60 torx.. going to go pick on up so I can do the belt... lol.. 3 weeks without car.. fun experience

[Steeler]

Happy you are close.
Joy to drive, sometimes painful to maintain

[rsutoratosu]

Its really not that bad, the hoses were cheap.. its the first major 'repair' I done in like 12 years... lol.. it was just hard getting some of the hoses on and off..

I order the t60 and e16 so I can do the belts.. my largest torx set was t55.. if i had known that 10 years ago I would have bought a bigger set.. so ill finish it next weekend.

At least Ill have fresh radiator fluid after all hoses are put back..

[Clearancediver]

Replace the temperature sensor ... part #5 in the bottom diagram. It's an inexpensive part. The sensor wouldn't seal/leaked when I did the refresh of expansion tank/hoses. O-ring wouldn't seal in the new hose as it was compressed due to age.

[rsutoratosu]

Sounds good, have in cart now.. ill order by wed if i found additional things to get.. lol

[rsutoratosu]

Originally I was only planning on replacing the bib on this hose. The other end where it connect to the thermostat didn't look kosher so I end up ordering a new hose.

Now since I have this new aluminum bib, should I use the new hose with the plastic bib or replace the end with aluminum one ?

[Clearancediver]

I would use the hose as equipped from the manufacturer