Strange noise (fan clutch?)

[waqas]

I know you folks love a little bit of detective work, so here's a chance: there's a strange noise coming from in front of the engine (67 250 with A/C and P/S). It sounds like a bad bearing or something like that. It began a few days ago as an intermittent sound, and then gradually got worse over about 30 mins. Now it appears to always be present.

Clues: I noticed some play when I move the fan forward/backwards. Also, the fan rotates very roughly (not sure if this is normal) when the engine is cold. All belts seem to be tight (< 10mm movement)

Isn't the fan supposed to be completely free spinning when cold? What are other tell-tale signs that the fan-clutch is bad? (besides the temperature trip point) What else should I look for? (and how?)

Muchas gracias amigos!

WAQAS in Austin, Texas

[tuultyme]

I had some noise at the front of the engine a couple years ago.  It turned out to be the water pump.  After easily replacing with new the noise was gone.  My mechanic used a stethoscope to determine the bad water pump.

Bruce; 268Blaugrun(green) 1970 280SL; IL

[waqas]

Stethoscope placed where? (I assume this was done with the engine running and the fan spinning) Was the 'scope attached to a long thingy and remotely placed near the pump?

Just for grins, I opened up the oil filler cap and the noise did not sound louder (except for the added valve train noise).

Thanks in advance,

WAQAS in Austin, Texas

[ja17]

Hello Waqas,

Yes, it is usually the waterpump. The sound resonates from the fan blade. The fan clutch usually has some play.  There are weep holes on the side of the waterpump. Eventually, as the bearings get worse, coolant may begin to seep from these. Sometimes you can temporarily make the bearing noise go away by squirting a little oil in these weep holes.

The fact that your W113 has AC will make the job much more difficult. Removal of the hood is not required but it makes the job soooooo much easier.

It is unusual for the fan clutch to make noise, but I would look into it first. I am not sure what you mean by "turns roughly".

Keep us up to date.



Joe Alexander
Blacklick, Ohio

[waqas]

Nice to hear from you Joe.

> I am not sure what you mean by "turns roughly".

Perhaps I phrased it incorrectly. Somehow, I thought the fan was supposed to be "free-running", but it turns with little drag. Is this normal? If so, how much drag is normal?

What exactly are the "weep holes" there for?

Also, is it possible for me to remove the fan assembly, replace the bolts and run the engine?  I want to see if the noise still remains afterwards (and allows easier access for Joe's "pipe stethoscope"(TM) method   )

WAQAS in Austin, Texas

[Vince Canepa]

1) Some drag when cold is normal.  The fan will not spin freely.
2) The weep holes are indicators for a leaking seal in the water pump.  A leaking seal can mean the bearings will fail in the future, but how long is a guess.
3) Yes, you can install bolts and run without the fan.  Just make sure the pulley/water pump will spin freely before you start the engine.  The regular bolts may be slightly too long since the mounting flange for the fan is no longer there.  Find shorter bolts or shim the regular ones with washers.

Vince Canepa
1967 250SL
113.043-10-001543
568H Signal Red
116 Caviar MB-Tex

[waqas]

Older thread, but I thought I'd start wrapping it up. Soon after the last post, 'strange noise' became intermittent, and then completely disappeared. So I thought I'd address it if/when it showed up again. Well, a couple weeks ago, it re-appeared, and this time, it was constant (not intermittent).

This morning, I set about to remove the fan/clutch assembly. I tried really hard to avoid removing the radiator, but the pulley bolts were just too long. I even tried loosening the rad and pushing a bit forward (about 10mm more), but it was still not enough. Compounding this entire effort was my damn a/c compressor!

I caved-in and removed the radiator. The fan/clutch came off, and I replaced the pulley bolts with shims (as suggested by Vince), and temporarily re-assembled the rad to re-start the car. The Noise was gone! (but now I began noticing a strange 'squeeking' sound... oh well). At least now I know the clutch is the culprit (of the original 'strange noise' at least   ).

I'll wrap it up once my fan clutch arrives.

WAQAS in Austin, Texas

[ted280sl]

WAQAS,
  You mentioned you have AC. When they put AC in our cars they added an idler pulley. It is really hard to see from on top. It is below the alternator. Anything that spind can be the culprit including the water pump, alternator or power steering pump. A stethescope will help detrmine where the noise is comoni from. If you do not have a stethescope do not try to steal one from a doctor. They tend to be very attached to them. You can use a rubber hose to deteremine where the noise is coming from.
Ted 1969 280SL

[waqas]

I never wrapped-up this thread, so now is as good a time as ever.

The "strange sounds" came back soon after my last post below, and I ended up replacing the water pump and the viscous fan clutch (along with thermostat and a host of gaskets and seals).

No noise since!