Preventative vanos job?

[Josephburn2.0]

I recently purchased a 2003 z4 3.0i with around 60,000 miles. I knew before buying it that the vanos seals were notoriously bad and needed replaced. As far as I can tell, that has not yet been done, however I also cannot see, hear, or feel any symptoms that it is going bad. My question, when the seals do start failing, do they harm anything else? In other words, should I replace the vanos seals now, even though they are not a problem, or wait to see if/when they do go bad?

 

[xp_mckenna]

I'm in a very similar position to yourself, having just picked up a 2003 3.0 but with a higher mileage.

My thinking is that there's no need to go chasing problems - the fault does not seem to be THAT common (to put this in perspective, I came from an RX8...their engines self destruct at 40k as mine did) and otherwise the engine is excellent. My thinking is to wait it out and see if any problems develop as it's not a massively invasive or terminal task (again, not like replacing an RX8 engine!)

 

[85genius]

I'd leave it if the engine sounds sweet, if you start to notice any kind of rattle, then replace the seals and do the disa valve at the same time

 

[cj10jeeper]

My 3.0i is a May '03 with 80k on the clock. Never even thought about replacing them and the engine runs sweet as.

As above why go chasing problems until symptoms appear.

DISA valve is different and I take that off every year just to see if it's rattling and again still not, so has the original.

 

[SonnyA85]

I would do it as preventative maintenance. The teflon seals are a lot better by the time you start noticing issues may cause more issues.

 

[GuidoK]

leaking vanos seals wont harm anything.
When the oil leaks past the vanos rings (inside the vanos cylinder), an oil relais goes on to pump more oil into that. Then the oil leaks out again and the relais goes on again etc etc.
Thats the ratteling you hear I think.
There is not something ratteling inside the vanos mechanism afaik.

But doing a preventative repair is always good as you know it must be done somewhere in the next 40k miles or so.
The hardest thing is to get the vanos off the engine, as it doesnt really clear the front chassisframe (the frame where the radiator fan sits on).
The easiest/most elegant workaround for that is imho to remove the motormounts which allows you to lower the engine by about 1-2inch (the sump rests on the subfram). If you know how and you have the car on a lift (and have a transmission jack), that's maybe a 30min job.
A capable/experienced mechanic can do the total job in about 2-3 hours I guess.

I did my vanos rings at 75k miles and they still sealed (I did mine because I installed cams). The underlying rubber o rings were stiffer than new but they still had some compliance for the teflon rings to seal. Thats where they go bad. The sealing rings from the vanos cylinder consist of 2 parts: a fairly hard brown teflon ring that does the seal (and sits on the outside of the piston that moves along the cylinder wall): thats made out of teflon to prevent wear, and under that teflon ring sits a rubber O ring. That Oring pushes against the teflon ring to have that teflon ring pushing against the cylinder (teflon isnt flexible so it cant create pressure from itself). That rubber O ring hardens over time due to heat and oil/fumes, thus loosing its compliance/springyness. Thats when the teflon ring starts to leak.

Checking the disa valve you can do on your driveway with very basic tools and takes 15min or so :lol:

 

[EdButler]

leaking vanos seals wont harm anything.
When the oil leaks past the vanos rings (inside the vanos cylinder), an oil relais goes on to pump more oil into that. Then the oil leaks out again and the relais goes on again etc etc.
Thats the ratteling you hear I think.
There is not something ratteling inside the vanos mechanism afaik.

But doing a preventative repair is always good as you know it must be done somewhere in the next 40k miles or so.
The hardest thing is to get the vanos off the engine, as it doesnt really clear the front chassisframe (the frame where the radiator fan sits on).
The easiest/most elegant workaround for that is imho to remove the motormounts which allows you to lower the engine by about 1-2inch (the sump rests on the subfram). If you know how and you have the car on a lift (and have a transmission jack), that's maybe a 30min job.
A capable/experienced mechanic can do the total job in about 2-3 hours I guess.

I did my vanos rings at 75k miles and they still sealed (I did mine because I installed cams). The underlying rubber o rings were stiffer than new but they still had some compliance for the teflon rings to seal. Thats where they go bad. The sealing rings from the vanos cylinder consist of 2 parts: a fairly hard brown teflon ring that does the seal (and sits on the outside of the piston that moves along the cylinder wall): thats made out of teflon to prevent wear, and under that teflon ring sits a rubber O ring. That Oring pushes against the teflon ring to have that teflon ring pushing against the cylinder (teflon isnt flexible so it cant create pressure from itself). That rubber O ring hardens over time due to heat and oil/fumes, thus loosing its compliance/springyness. Thats when the teflon ring starts to leak.

Checking the disa valve you can do on your driveway with very basic tools and takes 15min or so :lol:

I'm guessing due to the cams there is no fair comparison, but did you feel any benefit in mid range torque?

Phil! I know our cars are very similar in age and mileage. I'm just doing my Vanos now (great week for it... Not!) Even though the engine feels strong, they were frankly knackered which surprised me. My rocker cover gasket was also leaking, and thermostat housing hairline cracked! Gutted I have to wait for the 'stat to arrive. Hope yours is in a better state!

 

[cj10jeeper]

Ha ha - Don't start me looking for more problems. I already have enough fixing existing and doing actual and preventative maintenance on my cars...

Does remind me of my Dad's words. If it's broke take it apart and fix it. If it's not broke take it apart to look and learn, then fix it

 

[GuidoK]

I'm guessing due to the cams there is no fair comparison, but did you feel any benefit in mid range torque?

No.
As I said my vanos didnt have any problems yet. The seals were still sealing. When moving the piston inside the cylinder by hand, there was still some drag from the seals so no leak. So I probably could easily have driven a few years with those seals. There was no rattle whatsoever.

There can only be loss of power if the seals are leaking so badly that the oil feed cannot keep up with the leaking.

But as I installed cams it would be stupid not to change the seals as the much of the top of the engine has to be dismantled (incl. vanos). I also installed the anti rattle kit to reduce play in the vanos (bigger camlobes means bigger forces on the vanos, so you want to eliminate play to reduce potential wear) (the anti rattle kit has nothing to do with vanos rattle coming from worn seals BTW)