S54 Exhaust Camshaft Hub broken

[Zuzax]

During valve adjustment on my '07, it was noticed that my exhaust camshaft hub in the vanos had the usual tab breakage. One was cracked through but still in place (thankfully) and the other was doing all the vanos pumping work.

Other than obviously replacing the hub, what else needs to be done here? The shop is preparing an estimate but is already making noises that the head has to be pulled to do this.

I have 33k miles on the car (garage queen) so would anything else other that simple replacement of that hub be needed? Of course, there's a bunch of gaskets to replace for all the covers. Timing and such will be handled by the valve adjustment process.

How about the hub itself? Is the current OEM replacement improved since my engine was built? Are there "stronger" aftermarket hubs? I know Dr. Vanos has a cryogenically treated OEM hub that claims to be stronger, although it's $900.

Most of the things I find on the web are DIYs, which are informational, but not specific as to what's needed to avoid being sold up by a shop (not the dealer) to a complete vanos rebuild which may or may not be necessary.

Any help is greatly appreciated here.

[Zuzax]

The shop wants to replace the whole vanos system, replace the exhaust camshaft hub, and replace the sprocket bolts. Instead of pulling the head they want to remove the whole front clip and go in that way. Their estimate is just a biscuit under $7,000.

Seems like a bit of overkill to replace the cracked camshaft hub.

[Finnegan]

Massive overkill. Replacing and timing an S54 isn't easy to do.

Are they giving a reason they can't do what Stickmon did himself? At 33K miles I doubt the entire VANOS is dead.

http://www.zpost.com/forums/showthread.php?t=908450

[StickMon]

At 33k miles, I wouldn't think you would have to do anything but replace the hub, and the incidentals you mentioned.
The OEM hub still sucks.
I have the Dr. V "c300" hub, which I highly recommend.

The work can easily be done without removing anything but the cable for the right side hood latch.
That leaves plenty of room to pop off the Vanos, replace the hub, and put the Vanos back on.
Definitely replace the hub bolts. Preferably with grade 12.9.

[Finnegan]

^ And those recommendations are from someone who has done this work himself.

[Zuzax]

Originally Posted by StickMon

At 33k miles, I wouldn't think you would have to do anything but replace the hub, and the incidentals you mentioned.
The OEM hub still sucks.
I have the Dr. V "c300" hub, which I highly recommend.

The work can easily be done without removing anything but the cable for the right side hood latch.
That leaves plenty of room to pop off the Vanos, replace the hub, and put the Vanos back on.
Definitely replace the hub bolts. Preferable with grade 12.9.

This is great info. I just didn't pick up your post in my initial searches for some reason.

I'm going to tell them to just replace the hub. However, I am hesitant to replace it with the same OEM part that broke at 33k (or less) miles, so I will specify the Dr. Vanos hub. I wasn't sure if the C300 was a direct replacement for the S54, but I'm going to call Dr. V in the morning just to talk replacement and installation. It certainly looks beefier than the feeble looking OEM one.

Any ideas why they would want to remove the whole front of the car to work on the vanos? This shop has a good reputation and was straight up in their estimates and labor in the past.

[pokeybritches]

Removing the front end of a Z4 isn't exactly easy...

They probably think they need the clearance.

[StickMon]

When I first bought my car it had sheared camshaft bolts.
Brought it to an indie and they did the same thing.
They started at the front bumper and disassembled their way to the engine.
It may be a myth started by mechanics working on non-Ms, which I think do have a clearance problem.

The c300 is a direct replacement.

While they're in there, have them check to make sure the bolts behind the hub, that hold the spline tube in the end of the camshaft, are torx and not hex.
BMW changed from hex to torx, and presumably a better grade of bolt, somewhere in 2007.
The hex bolts are another thing that have a 100% chance of failure.

[elerner61]

I just recently had the exact same experience that you did, in for valves and found a broken tab.

My indy mechanic said the disk (which the tabs on the hub fit into) looked very good so that didn't need replacing. I reached out to Scott-TurboToys (www.tt-hub.com) for one of his hubs C300 hubs. These are the same C300 hubs that Dr. Vanos is re-selling.

For the valve work, new spark plugs and an Inspection II review and replacing the exhaust hub it ran me a little over $1,000 (not including the cost of the C300 hub). So all told it cost me about $1,800.

$7,000?? You can buy a rebuilt Vanos from Dr. Vanos for $1,350. There are a few videos out there showing the removal of the Vanos unit. One piece of advice that I haven't heard mentioned, I'm assuming the broken tab is still lodged in the disk. You want to make sure that piece doesn't drop, extracting it will be time consuming ($$).

[Finnegan]

Originally Posted by Zuzax

This is great info. I just didn't pick up your post in my initial searches for some reason.

I'm going to tell them to just replace the hub. However, I am hesitant to replace it with the same OEM part that broke at 33k (or less) miles, so I will specify the Dr. Vanos hub. I wasn't sure if the C300 was a direct replacement for the S54, but I'm going to call Dr. V in the morning just to talk replacement and installation. It certainly looks beefier than the feeble looking OEM one.

Any ideas why they would want to remove the whole front of the car to work on the vanos? This shop has a good reputation and was straight up in their estimates and labor in the past.

No idea why they'd want to do this outside of the myth theory. Show them these pics. This can be done without boiling the ocena. And RunnerX (friend of mine) did this in the wee hours and then showed up for a day at the track!

[StickMon]

Keep in mind that in that thread he had to jack up the engine because the broken tab fell down the rabbit hole.

I was able to carefully and successfully extract the tab, but I almost lost this bit down the timing cover.


Not sure how far it would have fallen. Don't want to know.
When I recently replaced my timing chain tensioner (which we'll all have to do at 100k miles) I was sure to stuff lots of rags around the timing chain.

[Finnegan]

Originally Posted by StickMon

Keep in mind that in that thread he had to jack up the engine because the broken tab fell down the rabbit hole.

I was able to carefully and successfully extract the tab, but I almost lost this bit down the timing cover.
Attachment 1229859

Not sure how far it would have fallen. Don't want to know.
When I recently replaced my timing chain tensioner (which we'll all have to do at 100k miles) I was sure to stuff lots of rags around the timing chain.

Good point. It's fair to say that what the shop is presenting as the case for a lot of prep labor is, at best, misguided though.

[Shipkiller]

If the tab falls in and goes to the bottom, then you are safe. There is NO WAY for the broken tab or a valve shim to get sucked into the oil system.

[bignosejim]

It's tight, but the vanos work can be done without raising the engine or pulling the front clip. I did it earlier this spring. If I broke a tab, I would end up going the turbotoy route.

Here's a thread from my efforts. It has some pics showing the clearance (not much but enough) just prior to removing the vanos.

[jdoublehcubed]

Considering how unfamiliar the shop is with this job (as shown by their estimate being way off), I would not think that they are a good choice to do the job at all. I'm sure if you call around you can find a BMW shop that is familiar with this exact procedure. It seems like your shop would be learning as they went; if you're paying an expert you want them to be an actual expert, not someone learning the job for the first time.

[Zuzax]

This story finally has a happy ending. After much "spirited" back and forth discussion, the shop relented on their initial approach (to keep my business) and also agreed to fully warranty (2 years, unlimited miles) the work without completely disassembling the front of the car or replacing the whole VANOS unit with stock parts.

To reach this agreement, we used an OEM replacement hub along with the Beisan Systems oil pump disk that has slightly tighter holes for the hub tabs. Car runs great again, just in time for it to be too hot to drive a convertible.

My personal unscientific theory of how this happened on a relatively low mileage car is due to hard starting. I have a bad habit of going long periods of time without driving the car, and without hooking it up to the CTEK, the battery gets weak or even goes flat. This makes it hard to turn over many times on start. Combine this with a failing voltage regulator (since replaced) and the resultant compromised, swollen batteries, you end up with several years worth of hard starts.

During the course of all this with the hub, I read several theories from E46 owners that relate to the hub tabs breaking over time and/or lots of mileage due to them having too much play in the holes in the oil pump disk. My low mileage situation might have been accelerated by the previously mentioned hard starts. On startup, there's not as much natural "cushion" that would be provided by oil, and a prolonged, slow, hard startup just makes this excessive "play" even rougher on the involved components.

It's just thin-air theory, but it has prompted me to stop "saving" the car for the future, because not driving it seems to be just as expensive and destructive (in different ways) as trying to preserve it.

I see an Autumn driving tour in my future.

[bignosejim]

Did they do all the Beisan fixes or just the pump disc and new hub? Glad you got it all fixed up.

[Zuzax]

Originally Posted by bignosejim

Did they do all the Beisan fixes or just the pump disc and new hub? Glad you got it all fixed up.

Just the disk and hub. At 33k miles the VANOS was ruled as sound. The only way the problem was found to begin with was from a visual inspection of the hub while doing the normal valve adjustment. One tab was sheared (but still in the disk) and one was cracking, but otherwise the engine was was running quite well.