rattling Merc fan

Oshbosh

Hi ,

the fan in my 420SEC started making a whining noise a while back which was intermittent, it has since changed to a rattling noise like its spinning off balance or something is stuck in there.

I got access to the fan box from the passenger footwell but couldn't really see what the problem was, the fan moved around easily enough by hand but a few minutes after starting the fan the rattling starts, it can get quite loud and didn't sound like it was doing any good.

My 230CE started doing the same after sitting in the garage for a month, perhaps this is a common Merc problem, is it likely to be something stuck in there or has the fan just come to the end of its life ?

thanks for your help

Osh

mike65

The fan is viscous I presume, sounds like the race that holds the ball bearings in place. Have you given the assembly a shake there might be loosness.

Mike.

Oshbosh

Hi Mike,

i'm not sure if its viscous, what does that mean ?

It is an electric motor. The fan itself doesn't look like a propellor type fan i.e. with blades coming out from the center, its more like a wheel with little blades housed around the outside edge. If i give it a shake by hand it seems okay and turns fine by hand.
The rattling is intermittent, if i let it run for a few minutes it can sound okay or more likely has a slight rattle, after a few minutes the louder rattle always starts though.

What is the 'race', you refer to ?

thanks

Osh

mike65

The race is where the ball bearings sit. A viscious fan clutch is the traditional Merc arrangment where the fan is on the end of the camshaft along with the water pump.

Mike.

Hifive

Mike, are you thinking of the engine cooling fan behind the rad?
I think Osh is referring to the interior heater fan as he can get at it from the passenger foot well.

mike65

Oh bolox! I scanned through the post (badly!).

Oshbosh ignore my first post completely

A rattling ventalation fan is of course electrical, I dunno that assembly so it could have bearings. I would suggest the fan spindle is'nt secure but you checked that, have you listened to it close up with the fan assembly exposed and running?

What year/chassis is the car?

Does the fan in this look familair?

http://www.detali.ru/cat/MB/B83001000005.0051.gif



Mike.

Oshbosh

Hi Mike,

My car is a 1990 420 SEC (W126) so the later model, post 86 face lift, not sure of the chassis number i'm afraid.

The fan looks like the part numbered 82 in the diagram. I did listen up close but couldn't see what was making the noise.

There was a screw off center from the middle of the fan which i checked, it was pretty secure although was not screwed in all the way, only as far as it could go, it was sticking up by maybe 1/2 inch but wouldn't go in any further. There was a little dimple in the sponge covering where the screw head rested.

Where is the spindle in the diagram ?

thanks

Osh

mike65

That diagram is'nt the best - its only really designed to show parts in general context.
The spindle would be the arm which the fan (or whatever) slides over and along and which is not in that pic. If the spinning fan bit is the problem then just giving it a push this way and that should make the rattle either quieter to louder I'd have thought.

Mike.

Oshbosh

i'll have another look, didn't want to stick my hand in there ! Maybe some WD40 will help, the problem started with a whining which sounded like something needed oiled, hopefully the problem hasn't worsened now,

thanks for all your help guys,

Osh

mike65

If the fan is inside a tight looking enclosure try squezing it, it could be something as simple as the fan getting warm and the plastic expanding a fraction, then rubbing/chaffing against the surround.

Mie.

Oshbosh

thanks !

Dades

The fan on my '72 107 has a squeak too.

It's somewhat intermittent though. When it starts you can nearly always get it to stop by changing the fan-speed up or down a level.

Probably doesn't help - but at least you know you're not the only one!

Oshbosh

mmm. i suspect this is a common Merc problem.

I've just realised what it sounds like once the real rattling starts, the waste disposal thing they have in kitchen sinks in America !

8~)

I've heard this on a few cars that I've had parked up for a while. I assume the bearings/grease dries up a bit through lack of use. If you've had you hand it and all feels secure maybe try running it at varying speeds to see will it quieten down after a few minutes. If you think it sounds very bad, switch it off!
The only other thing I can think of is that maybe a pebble has got in there and is being thrown around?

Oshbosh

it does sound like something rattling around in there all-right, when i move it by hand it goes around easily enough. I guess i'll have to take it out completely and see if something's in there. I couldn't see how to get it out though but my head was upside down at the time:)

I think the air intake vents in the engine bay frequently get clogged with leaves etc on Mercs so perhaps i need to clear these out as well,

thanks !