Vanos solenoid on N52

Z

Z4 3.0si Coupé

Member
Hey there,

Since I am facing the famous vanos issues with my BMW Z4 Coupe with N52 engine, I decided to order new solenoids at the local BMW dealer.

Symptoms are:

- rough idle
- low power output
- sudden power increase above 4000rpm (not like normal flatspots)
- once I had a CEL which went away after few miles and restart
- Codes on vanos, engine timing and mismatch between crank and camshafts


Now my question: how did you replace these solenoids? On YouTube I see all the nice DIY movies, but these are all on E90 or E82 where you have plenty of space around the engine. At the Z4 this is a bit different. There is only a gap of 5 centimeters between the engine and the radiator cover plate. I tried to remove the radiator cover plate, but makes no difference. So how did you do this on Z4s I don't even have enough space/leverage to undo the connector due to my large hand :x

Thanks!!
 
Hi,
It's a bit of a squeeze, but it can be done without removing anything except the engine cover (And that's only to let a little more light on the area).
Stu.
 
Thanks a lot, Stu!

Removing the cover just gave me that little more space for light and pulling the connector.
The DIY for Z4 is different btw, also because of the fact that the layout of the connector cables is different then on 1 series, 3 series, X3 etc. Again, a tighter fit then on other BMW models.

Anyway, one dirty solenoid came out, engine is still running and now I will go for a longer test drive and hopefully notice a huge difference :)
 
How did you get on with this? I have a slightly rough idle, only really noticeable on the rev counter and i've noticed a few times a strange increase in power over 4000 as you mentioned. Almost feels like a big turbo car coming on boost. No eml or fault codes though. Same car as yours, with 86000 on. Was it worth doing and are there any "O" rings to replace? thanks.
 
stupot67 said:
Hi,
It's a bit of a squeeze, but it can be done without removing anything except the engine cover (And that's only to let a little more light on the area).
Stu.
Click to expand...

Yep, did this the other day. Pop the cover off for a bit more light and then it's pretty straight forward.
 
cossie si said:
How did you get on with this? I have a slightly rough idle, only really noticeable on the rev counter and i've noticed a few times a strange increase in power over 4000 as you mentioned. Almost feels like a big turbo car coming on boost. No eml or fault codes though. Same car as yours, with 86000 on. Was it worth doing and are there any "O" rings to replace? thanks.
Click to expand...

Hi Cossie,

In my case it made a huge difference. Like really huge. The overall behavior of the car changed. It is like going from a 2.5 engine to a 3.0.

Smooth idle like a BMW L6 engine is suppose to idle. No more hesitation in lower rpm and way more power over entire the rpm range. The 4000 rpm flatspots is barely noticible anymore.

I have to say: I replaced both the solenoids, but only the inlet was the broken. The solenoid that came out was totally shot. In the new one you would feel and hear something moving freely inside the solenoid when you shake it. This was totally stuck in the old ones. I even tried to clean the old ones with brake cleaner, but this made no difference. BMW also change the solenoids over the years, so this also made me decide to replace them, because BMW is not just changing parts for fun :).

Mileage of the car: 75.000
Maintenance at BMW dealer
 
Z4 3.0si Coupé said:
cossie si said:
How did you get on with this? I have a slightly rough idle, only really noticeable on the rev counter and i've noticed a few times a strange increase in power over 4000 as you mentioned. Almost feels like a big turbo car coming on boost. No eml or fault codes though. Same car as yours, with 86000 on. Was it worth doing and are there any "O" rings to replace? thanks.
Click to expand...

Hi Cossie,

In my case it made a huge difference. Like really huge. The overall behavior of the car changed. It is like going from a 2.5 engine to a 3.0.

Smooth idle like a BMW L6 engine is suppose to idle. No more hesitation in lower rpm and way more power over entire the rpm range. The 4000 rpm flatspots is barely noticible anymore.

I have to say: I replaced both the solenoids, but only the inlet was the broken. The solenoid that came out was totally shot. In the new one you would feel and hear something moving freely inside the solenoid when you shake it. This was totally stuck in the old ones. I even tried to clean the old ones with brake cleaner, but this made no difference. BMW also change the solenoids over the years, so this also made me decide to replace them, because BMW is not just changing parts for fun :).

Mileage of the car: 75.000
Maintenance at BMW dealer
Click to expand...
Nice one! I'll take mine out when i get a chance and check them. Could i be cheeky and ask the price and part numbers please. Cheers!
 
The part number for both solenoid is the same: 11 36 75 85 425. The price in the Netherlands was 77EUR per piece without VAT.

But even when you only have 25% of the effect I had, I would recommend you to just replace the two of them :)
 
Bought and fitted tonight. Idle has improved, rev counter needle is near static now and it definitely pulls much smoother. Bit of a t##t to get the new ones in with the new seals. Got them for £155 the pair including a "can I have some discount please" , "yes, 10%!" Although mine hadn't thrown any codes, they were clearly on the way out. Cheers for the heads up!
 
cossie si said:
Bought and fitted tonight. Idle has improved, rev counter needle is near static now and it definitely pulls much smoother. Bit of a t##t to get the new ones in with the new seals. Got them for £155 the pair including a "can I have some discount please" , "yes, 10%!" Although mine hadn't thrown any codes, they were clearly on the way out. Cheers for the heads up!
Click to expand...
Where did you buy them from? Are they OEM or genuine BMW?
 
What are the symptoms?
Is it just the idle and flatspot or are there others?

I'm worried as my idle isn't smooth when cold plus it's done over 100k.
 
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