Merc SL - Dashboard Ghost!

Dades

Was driving on a short trip last - 15 mins through the 'burbs, and got the weirdest sound coming from the dash of my '72 SL.

I only lasted for a couple of minutes but it sounded like there was a ghost behind that dash - that is - a long wooo'ing whir that changed up and down in pitch, and a mild vibration. It seemed to be *roughly* related to speed, but not at higher revs (tried revving in neutral).

After I had slowed to a full stop at some lights, it kind of faded away and then stopped entirely. Coming home all was quiet.

Anyone any thoughts on this?!

peasant

could be that the wire/shaft that drives your speedometer has come out of its bearing / is generally getting loose(er)

tc20

i've occasionally encountered the same "woohoohing" noise driving my '72
W114. Haven't had it happen for a while, and when it did occur, it always seemed to be on v cold or frosty mornings. The noise would pass after 5-10minutes driving. I think peasant is bang on with the speedo cable, possibly it needs lubing. Its just another quirk that age has bestowed on my car

Dades

Thanks guys. I figured along the same lines - once you isolate the source of the sound there ain't too many options! And tc20 - it was brass monkeys last night.

My concern is I'm driving Dublin to Limerick tomorrow and if that sound starts in Naas and keeps up I'll be a jibbering mess by the time I get there! Still not enough of a threat to make me drive the wife's Nissan though.

Sounds like a dash-out job to rectify?

tc20

i guess you're well down in Limerick by now in the SL

Not sure about the clocks in the SL, but in my W114 they just pull out, with some gentle rocking back n forth. TBH it must be about ayear since i got that noise on a regular basis. Then, without any interference from me (apart from pulling the clocks out) the ghost left the machine.....made one re-appearance late last year, and thats it.

MercMad

Yeah its most likely the speedo cable or the heater fan motor.

The speed cable should be replaced, its not worth trying to lubricate it and its a fiddly job but not a nightmare dash out job thankfully !

The clocks are usually held in with a bracket and knurled knob, unless someone has been there before and just pressed them back in.

The heater fans do give trouble on W107's though, they switch themselves on and off then eventually stay on blowing hot air into the cabin. They can go on for years like that but will eventually burn out the motor or melt the plastic brush holder. The cause is usually a simple bi-metallic switch that can be accessed easily from the bulkhead side.

Dades

Cheers MM - was about to post with tale of my weekend!

Decided to risk driving the SL to Limerick on Saturday, but the intermittent noise became pretty much constant - so 15mins out I had to turn about, go home and swap cars.

It seems the vibes are very much behind the dash rather than the heater which is working as normal. Pressing on the instrument cluster alters the sound from the vibration. Although the speedo still functions... hmmm!

mike65

Sounds like you took the Nissan without need if a press on the dials could make a difference.

That said getting stuck in Laois for a night had you broken down is all part of the fun of classic ownership isn't it?

Mike.

Dades

mike65 wrote: »

That said getting stuck in Laois for a night had you broken down is all part of the fun of classic ownership isn't it?

I feel lucky to make it back at all this weekend!
4 people killed on the road we were traveling on Saturday morning. Yikes.

MercMad

Mmmm well it may be speedo cable or rev counter. Actually the rev counter is electronic on the 107's.

You could disconnect the speedo cable at the gearbox easily enough to verify thats the fault !

Dades

Cheers MercMad.
I'll be pulling some cables this weekend!