help! z4mc problem :(

[z4mcoupe]

Hi everyone,

Long time reader, first time poster...

I'm hoping to lean on the specialist knowledge on this forum to help me with a problem with my Z4MC. Sorry for the long post, I'll try and explain the issue I have encountered.

While out on a Sunday afternoon drive, I noticed an odd vibration in the car as I coasted to a stop (in neutral) before engaging first. I normally coast the last couple of car lengths before a stop to then re-engage a gear. As I took off in first, I experienced very loud vibrations to the point i couldn't hear the engine. I thought i had stalled the car, but hadn't. I continued to drive on to see if it was just a glitch or something more serious... This is what I can say about the issue:

- definitely a loud drone / hum / vibration as I'm coasting to a stop (no gears engaged)
- loud drone / hum / vibration occurs whether in gear on in neutral as I roll to a stop
- vibration and odd engine tone as it idles
- loud and noticeable vibration as I take off in first and then as I continue to accelerate in second gear, once i clear 2,000rpm it gets better
- problem is less noticeable at higher gears, speed and RPM
- the engine continues to feel 'strong' if that makes sense (not that I pushed it)
- no engine light or warning lights on dash
- oil temp in working range
- seems to be worst with AC on

I basically nursed it home. I've read so many things owners have faced with mounts, rod bearings, vanos etc that I'm fearing that everything has failed on the car!

Car is 07 Z4MC with 41,000 kms.

Any ideas??? I'll be taking the car to a workshop next week.

Thank you!

 

[z4mcoupe]

I’ve done a bit of recon by sticking my head under the car. I’ve noticed 2 moist areas behind both front wheels of the car. The car hasn’t seen rain in a long time. A quick wipe and sniff says it’s an oil of some kind... the engine bay looks dry as far as my head and iPhone torch will go.

Could be a completely unrelated issue!

 

[Z4M-2006]

Maybe the engine mount bolts have broken , not uncommon

Can’t think why oil would be around through ? Power steering pump?

 

[buzyg]

Could be the crank shells / rod bearings, have failed. I do hope it's not that though.

Does it only make a noise when moving. If so it's not that.

Welcome to the forum.

 

[r0bb0]

Engine mounts?

 

[Jembo]

I’m guessing you are in Europe - do you know anyone local who may have a ODB port reader?

Is it fresh oil or been there a while

We can all suggest things - such as coil packs - though I believe getting the codes read is the next best step

Good hunting getting her sorted

 

[Ewazix]

I believe that the engine mounts are oil filled? If they have gone you would suffer nasty vibration and noise on take off plus some hydraulic oil spillage.

 

[MrPT]

The “worse with AC on” thing is interesting. Worth checking the radiator fan and also the auxiliary belt (although if the belt were fouling on something it wouldn’t make any difference whether the AC was on or not because the clutch is on the compressor pulley).

I wouldn’t drive it any more. Take the plastic undertray off so you can see the sump and the middle part of the ARB (should only take 5 mins), open the bonnet and try and eyeball both engine mounts plus brackets/bolts and the clearance all around the engine - particularly underneath. Jacking the front of the car up and removing the front wheels will make it easier.

 

[Vanne]

Drive shaft carrier bearing is what I would check. (For the guy who suggested that the engine mounts are oil filled?? They are not.)

 

[scootr]

Fan or fan blade ready to come off?

 

[z4mcoupe]

Thanks so much for everyone’s replies. There’s plenty there to think about and until it goes up on a hoist and the undertray comes off it’s hard to say definitively.

@Z4M-2006, @r0bb0, @Ewazix - My initial thoughts was engine mounts, but they were replaced by the previous owner less than a year ago. Can mounts fail so quickly...? Then again at 41,000km I wouldn’t have thought mounts were needed to be replaced in the first place. I didn’t realise mounts were oil filled but on googling I see some are... unsure whether mine are or not.

@buzgy - thanks for the welcome. I’m hoping it’s not rod bearings. The noise / issue is there at idle as well as on the move at low speeds.

Jembo - I’m in Australia but there are good workshops around me. Would a scan show an issue despite no warnings on the dash?

@MrPT - I’ll try and have a closer look today to see if I can get the car up on jacks to take a look, and also deeper into the engine bay. I’m guessing the mounts won’t be visible at a peek and I’ll have to go deep into the underside /engine bay to eyeball it

Regardless I fear there’s going to be a decent repair bill waiting for me!

I’ll keep you guys updated. In the meantime this is my ride post the sad drive home...

 

[Mr Tidy]

Sorry I can't offer any technical input, so I won't try - but I hope it turns out to be a relatively simple fix, rather than a wallet-buster.

Having only bought my M Coupe in December this is the sort of thread that scares me!

Welcome to the forum anyway.

 

[z4mcoupe]

Sorry I can't offer any technical input, so I won't try - but I hope it turns out to be a relatively simple fix, rather than a wallet-buster.

Having only bought my M Coupe in December this is the sort of thread that scares me!

Welcome to the forum anyway.

Thanks Mr Tidy - I hear you! I was fearing something to go wrong but did all the right things before purchase like a pre-purchase inspection etc. I guess it's one of those things that happens.

Hoping to get the car towed to a workshop by the end of the week and then I should have clarity over what I'm facing.

It's like the 6th time i've driven the car since i've got it so quite bummed.

 

[ph001]

You can very easily check the radiator fan (as mentioned above) yourself just by lifting the bonnet. Spin the fan by hand and check if any blades missing.

 

[BMWZ4MC]

Where are you in Aus? I’d be happy to have a listen if you’re somewhere near.

 

[Jembo]

Where are you in Aus? I’d be happy to have a listen if you’re somewhere near.

The power of the Forum...

Worse case maybe even a Facetime/Skype video call with BMWZ4MC

 

[z4mcoupe]

2

Thanks so much. I’m in Melbourne. I can see from your signature you are in Sydney?

 

[MrPT]

@MrPT - I’ll try and have a closer look today to see if I can get the car up on jacks to take a look, and also deeper into the engine bay. I’m guessing the mounts won’t be visible at a peek and I’ll have to go deep into the underside /engine bay to eyeball it

While the bushes in the mounts can perish, it’s actually the bolts that hold the mount to the engine block that are known to fail; the driver’s side especially. See this thread for more info.

On the plus side, it’s not as catastrophic a failure as it might sound (especially if the car is still drivable) and can often be fixed, in situ.

I’ll keep you guys updated. In the meantime this is my ride post the sad drive home...

Very nice.

 

[BMWZ4MC]

2

Thanks so much. I’m in Melbourne. I can see from your signature you are in Sydney?

I am, so it’s a bit far to drop by!
It does sound like an engine mount bolt has failed though from what you’ve described.

 

[z4mcoupe]

Hi Everyone,

I wanted to provide an update to my issue and also thank everyone for providing their suggestions and online diagnosis! To those who called out the engine mount, bingo!

One of the engine mounts had the bolt completely missing from it. So it was assumed it wasn't torqued properly and eventually worked its way out. The other mount had the bolt head snap off which meant half the tread was inside one end. The conclusion there was that the second mount failed due to the extra stress of the first mount failing. That caused the engine to move slightly downward and forward, resting on the front cross member which caused the awful vibrations and resonance.

An inspection of the transmission mounts identified one of the two mounts being loosely secured and so was re-torqued.

All of this after another workshop installed new engine and transmission mounts in August 2019 (before I purchased the car) and the car only having travelling 1,000kms. I'll be having a word to this other workshop but I presume it will go nowhere especially as I'm in another state... I'm of the belief they should foot the bill for this and will be asking!

Back to enjoying the car once I pick it up on Monday.