SL55: Mystery whining noise (from transmission?) when cold

[neeklaus]

Hello fellow Benzers,

My beloved SL55 has been running more or less peachily since I bought it 2.5 years ago (thanks owed to these forums) and 30,000 miles later.

However, since about the end of last year an odd whining noise would arise, always when the engine is cold.

-The first instances were rare, infrequent.
-Gradually it would become more common, especially when it had rained over night or the outside temperature had changed noticeably.
-Now, I hear it without fail whenever I start the engine cold.

The noise goes away once the engine is warmed up, however.

I have made a video so you can hear for yourselves the difference between warm and cold running:

It was very pronounced last week when I drove through Switzerland from Italy and stayed there overnight. The cold temperature in the mountains seemed to make the noise louder, also exacerbated with heavy engine braking driving down steep inclines. Unfortunately I didn't film that.

In addition to the noise, I can also feel a very slight vibration in the steering wheel. Imagine the kind of vibration you would feel through your hand on a table if your phone was vibrating nearby.

The noise itself seems to be coming from the forward-centre of the car, although it's quite hard to pinpoint an exact location. You can also hear the noise 'accentuate' if riding over a bump.

It's very difficult to get a garage to look at it because by the time I get there, the engine has usually warmed up and the noise has gone away!

I am going to see if I can investigate this when I get the car MOT'd in a couple of weeks – leave it with the garage overnight and show them the problem in the morning when the engine is cold.

Has anyone else had this issue, or any inkling as to what it could be?

 

[neeklaus]

Oops, sorry wrong topic.
Would an admin please kindly move this?

 

[Uncle Benz]

Transmission fluid level check would be first thing on my list.
Engine mounts, possibly

 

[Uncle Benz]

 

[sausage]

+1 For transmission fluid.
Does the noise only occur when driving, or when stationary (and cold) as well?

I have a 2009 SL350, local indy tells me gearbox service at 70k miles. Could it be time to have yours done?

 

[Uncle Benz]

The rear gearbox mount can go weak, and creates a lot of tunnel vibration on start up. It can lessen as the car warms up too. Or propshaft centre bearing? It’s difficult to be sure of anything without seeing it

 

[neeklaus]

+1 For transmission fluid.
Does the noise only occur when driving, or when stationary (and cold) as well?

I have a 2009 SL350, local indy tells me gearbox service at 70k miles. Could it be time to have yours done?

It's only when driving, not stationary.

I'm at 94,000 miles and counting – probably about time!

 

[neeklaus]

Transmission fluid level check would be first thing on my list.
Engine mounts, possibly

Yes I was going to ask the garage here in Italy about the transmission fluid too – before I drive another 1000 miles home!
I think we replaced the engine mounts a couple of years ago...

 

[sausage]

Fluid and you should do the filter too, I believe. Worth a go, although might be pinning too much hope on a quick and easy solution. My fingers are crossed for you.

 

[00slk]

Blimey Nik, thought upu had fallen off the edge of the world
If it was low on automatic fluid it would sendcit into safe mode like what happened to my 55 when the transmission fluid got low when a switch leaked.
That does sound like low oil like you hear on manual gearboxes?
How have you been in the last 2.5 years?

 

[neeklaus]

Thanks sausage for the well wishes.

Hi Peter! Yes I’ve been absent a while. Very busy moving around a lot and it must be said enjoying my SL very much. It’s such a capable car, I feel I can go anywhere with it and always impressed how much I can stuff into the boot and behind the seats.

I’m thinking about worst case scenario I can’t get it looked at here before I drive back to the UK. The transmission seems to be working fine - I’ve been driving it as usual and apart from the noise everything seems to be working normally. If I can’t get it to a garage before I drive the 1000 miles back home, might I be doing some irreversible damage?

The trouble is I need to get it back to the UK in a week’s time for the MOT, amongst other engagements… I can’t really wait around any longer to have someone look at the car beforehand. So there is a possibility there won’t be any availability at the local garage in time.

I’d really prefer to have it checked out but as you say there’s been no cut outs so perhaps if worst comes to the worst it’ll still be ok to drive it home

Still hanging on to your ‘55, and the 500? Hope all’s well with you (and the garage!)

 

[00slk]

We have done a lot to the house and the garage is all but finished, got the 2 poster lift inside as well as the one outside, will leave the outside one for the older cars. Still waiting to have the concreting done. Hoping it'll be sorted before we go to New Zealand in October.
Hanging on to the 55 as long as possible ( might have to sell her to pay the power bill)
Sold the 500 over 2 years ago now, bought a 350 SLK which we had for a year, sold that and the Missus is running around in a 250SLK, had that over a year now.
Your whining sound, I hope it's not internal, had the same noise in my 02 plate Laguna auto, it was quite noisy when cold however it was barely audible when hot. Turned out to be a spigot shaft bearing had siezed and was spinning the bearing in the bellhousing casing. I am not sure if the r230 55 transmission has the same design or not as the video that Uncle Benz posted. These transmissions are fairly hardy, the only concern is contamination by fine metal going through the internals?
Do hope it's not going to be a major for you.

 

[sausage]

Fluid and you should do the filter too, I believe. Worth a go, although might be pinning too much hope on a quick and easy solution. My fingers are crossed for you.

Just to be clear. By this I suggest you consider a gearbox oil service, which you should be able to get done quite easily. There is no guarantee it will help, but if it is like my 2009 then it is due. If the oil has lost some of it's quality it might result in higher noise levels. Good luck!

 

[neeklaus]

We have done a lot to the house and the garage is all but finished, got the 2 poster lift inside as well as the one outside, will leave the outside one for the older cars. Still waiting to have the concreting done. Hoping it'll be sorted before we go to New Zealand in October.
Hanging on to the 55 as long as possible ( might have to sell her to pay the power bill)
Sold the 500 over 2 years ago now, bought a 350 SLK which we had for a year, sold that and the Missus is running around in a 250SLK, had that over a year now.
Your whining sound, I hope it's not internal, had the same noise in my 02 plate Laguna auto, it was quite noisy when cold however it was barely audible when hot. Turned out to be a spigot shaft bearing had siezed and was spinning the bearing in the bellhousing casing. I am not sure if the r230 55 transmission has the same design or not as the video that Uncle Benz posted. These transmissions are fairly hardy, the only concern is contamination by fine metal going through the internals?
Do hope it's not going to be a major for you.

yikes, hope you get to hold on to the 55. energy bills are getting outrageous. A friend of mine just bought a 350 SLK - great fun little car. much sportier than the SL I found, SL much more a cruiser. You can really feel the weight difference.

Fingers crossed I can get the transmission looked at before I drive home.

 

[neeklaus]

Just to be clear. By this I suggest you consider a gearbox oil service, which you should be able to get done quite easily. There is no guarantee it will help, but if it is like my 2009 then it is due. If the oil has lost some of it's quality it might result in higher noise levels. Good luck!

Thanks! yes I think I will go to the garage first thing Monday and see what they can do. Gearbox oil service sounds like a good idea.

 

[neeklaus]

The garage drove it cold this morning and suggested it could be the ABC pump. But I am skeptical because the noise is only present when driving, not stationary. After watching failing ABC pumps on YouTube it seems the noise they make is different - a bit lower. That doesn’t necessarily rule out the ABC pump, although it still makes me doubtful.

I have asked if they checked the transmission fluid level but not heard back yet.

They want to test drive it cold again tomorrow morning… we’ll see how it goes…

 

[alexanderfoti]

Sounds more like gearbix than ABC to me.

Easy to rule out anything on the aux drive. Start it with the belts off.

 

[neeklaus]

Had to collect the car early as needed to return to UK earlier than planned.

They had the car for a couple of days and couldn’t locate the source, although they are convinced it’s the ABC system. They said the noise is present in neutral as well as in gear.

Made it over the alps last night and stopped overnight in France. This morning the whine is still here - although it disappeared when I tested shifting into neutral, which suggests again to me that it’s gearbox related.

I’ve just dug out a previous service invoice which shows the gearbox mounts, oil filter and fluid were all replaced May 2021… the mystery deepens…

 

[neeklaus]

Another invoice from 3 years ago (the year before I bought the car) shows the ABC pump was replaced. I’ve kept pretty on top of ABC maintenance since I bought it too - it would be annoying if it indeed turns out to be ABC related!

 

[00slk]

Another invoice from 3 years ago (the year before I bought the car) shows the ABC pump was replaced. I’ve kept pretty on top of ABC maintenance since I bought it too - it would be annoying if it indeed turns out to be ABC related!

ABC would be cheaper than transmission replacement though Nic??