What to look for when buying a Z4

[SG123]

Hello,

I am looking to purchase a used Z4. I have always wanted one but was not in a position to buy one. But that is no longer the case and I am able to buy one now. I will admit when it comes to car specs I don't know much. I am hoping that someone on this forum may be able to give me some advice - what to look for what to stay away from etc. My budget is 25Kish, ideally less but could go over for the right deal. Any advice and pointers would be appreciated. Thank you in advance.

[KennyP]

If you are looking for a 35i:

Check what index injectors are on the car. 4 bolts to remove engine cover and then you can see injectors. They have numbers on them and the end is -12 or -07 etc... That number tells you what index they are... It would be great if they are all -12. Index 12 are the newest and probably problem free. if they are like index 7 or 5 then you may have to buy new injectors one day. New set of index 12 is like 1300 usd.

While there you can pull some coilpacks and check the date on them. OEM Bosch surely had a date printed on them. That way you will know if they have been changed. If they are Delphi or Eldor brand then even better!
Also you can check valve cover while engine cover is off for oil leaks, cracks.
New valve cover is 400usd.

Check front of the engine behind serpentine belt for oil... If car has oil filter housing gasket leak then thats where you see oil.

If you can look under the car and have DCT transmission. Peek behind the plastic covers at the transmission to see if its dry. DCT oil pan gasket can leak. Doing DCT service will fix it with new gasket.

Engine idle should be constant not jumping.

Wastegate rattle... Can listen for it while revving the car.. For reference search youtube for N54 wastegate rattle and watch some sound clips.

Check sunvisor mirrors. Sunvisors have heavy spring and it pulls them back with a bang and can break the mirrors inside. Always put them back gently.

Trunk divider plastic hinges. Check if they are ok. Too much stuff in the trunk under it while folding the roof and these plastic hinges can break.

Heated seats: have them on for like 10 minutes straight. If hey start to get too hot by that time you may have a faulty heating element in the seat bottom. I had to replace mine because of that issue.

Rear lights have moisture issue... check if they are dry. Ask if have been replaced. Aftermarket replacement lights are around 200 usd a corner. OEM is 300 i think.

And other stuff like wheel bearing noises, suspension noises, leaking wet struts.

Also can check oil change intervals in service book or invoices. Idrive gives a long service interval on earlier cars. BMW later revised oil changes to be a lot more frequent. If idrive hasnt been updated it would still say to change oil every 25000 km or something like that. It actually should be like 10000km. Of course people who dont read forums probably dont even know that. Would be nice if the engine had more frequent oil changes but you cant fault the seller for doing as the car says.

If car has bmw style 296 19 inch wheels ( do google image search) then check rear wheels inside edge for cracks. These wheels look nice but are prone to cracking. I have them and have repaired them twice in 4 years.

[SG123]

Thank you for the great tips! I'll be sure to check those things out when I find a car that has potential. I really appreciate the info.

[bryanhoag]

That was a fantastic review. I just had to replace the 296 wheels on my 35i due to cracking.

I would also suggest operating the roof a number of times to make sure it functions correctly. Look for any areas of wear in the hydraulic harness. Repairing the roof mechanism can be expensive as well as a diagnostic dilemma.

[ikura56]

I bought a Kcan cable and downloaded the MHD app. That way you can plug it into the car and read any codes or shadow codes. Also, you can check the flash version. It was only 25 dollars. I almost bought a 35i locally then ran the test and found 2 problems, IBS missing and low oil lever. The owner says he changes the oil every 3k miles. Sounds like an oil leak or burning oil to me. If I didn't have the cable I wouldn't have known.

[KennyP]

Originally Posted by ikura56

I bought a Kcan cable and downloaded the MHD app. That way you can plug it into the car and read any codes or shadow codes. Also, you can check the flash version. It was only 25 dollars. I almost bought a 35i locally then ran the test and found 2 problems, IBS missing and low oil lever. The owner says he changes the oil every 3k miles. Sounds like an oil leak or burning oil to me. If I didn't have the cable I wouldn't have known.

Carly app can do some checks aswell... like check if the mileage is constant in all modules and havent been tampered with.

On oil consumption... Idrive starts notifying driver to add 1 liter when its 1 liter low from max... Before that if you dont check it yourself in the menu you would not know...
My car have asked extra liter of oil twice... both around 7000km after oil change... Pretty much telling me its time to go and do an oil change.