nile13

The engine fan on my '95 C2 seems to whistle and make general odd grumbling bearing-like noise at or near idle. I have not completely localized this noise, but it seems to be coming from the fan housing. It also seems to go away above 2-3K RPM. Or maybe it's just drowned by other noises at that point. Oh, the radio is picking up some whistling as well, especially on AM at low RPM.

So... is this fan or alternator issue? In either case, what's the best remedy and how hard is it to pull the fan out? Any good way of localizing the source other than listening with a long screwdriver or stethoscope?

Any suggestions/thoughts?

CalvinC4S

When alternator bearings go out they will make the noise you discribe.
If you can change your belts, you can change your alternator.

nile13

Calvin, that's why I suspected the alternator as well.

It's a bit cold out here, but I might be able to swing some garage space if needed. Any tips on alternator change besides the standard DIY writeups? What do alternators cost nowadays?

Thanks!

Macca

I had a low "whistling"/"squeeking" noise on idle occure after switching to RS single Pulley. No rumbling or bearing noise. I had the alternator taken out and the fornt and rear bearing replaced. Had i painted while out to add some bling. After refitting the noise was still aparent. It was finally decided it may be due to thefan moving at a different speed causing a differnt kind of "whurr" as the air passed throgh it. Dissapears immediately the throttle is touched. I had RS LWFC installed at same time with Steve Wong chip programmed to remedy early 994 stalling so its possible an increased idle speed could also have attributed. If you have made none of the above modifications recently then I would go with replacing both bearings in the first instance and maybe have your althernator fan and shroud tidied up same time....

Cheers
M

nile13

Macca, thanks!

This car is mechanically stock. Actually, my previous 140K mile C2 with LFW did not make the same noise. The noise sounds very bearing-like, so I think the alternator diagnosis is correct.

The question is - what are the part numbers/[pricing on the bearings and where do I get them? How hard to replace? Should probably replace the voltage regulator at the same time. AutoZone has remanufactured alternators for $150. I've had various levels of success/failures with their alternators, though.

PS. The noise that you describe might actually be due to the seizing belt tensioner. I've seen it discussed and your noise might be coming from there if new alternator bearings did not get rid of it?

Macca

Hi mate. This is the info I found on another thread that I gave to my mechanic. They werent expensive from memory perhaps $40 the pair. My whistling is a bit of a mystery. perhaps being an early car with an increased idle the fan is producing the noise....

Bearing # is 6201. I have purchased some from bearingsdirect.com (no affiliation).
You want the version that is rubber sealed, both sides. FWIW, I did not order the "loose fit" version: http://bearingsdirect.com/store/inde...t_detail&p=208

You will need a bearing puller and some method of pressing the bearing and spacer back onto the shaft.
For info, the part number to look for should be 6201 2RS . ( 2 Rubber Seals ) original is 6201 2RSR FWIW

nile13

Thanks again, Macca!

See my comment on the tensioner, though. Owners reported whistling from it before, so this might be your noise. It's easily lubricated, though.

Macca

Hi Mike. Thanks for the advise. I did check that. I used a cardboard tube to my ear to localise the sound and it came from the alternator area. I could lift the tensioner wheel from the belt and it would continue. I will however have a look at this again because as you say it is a common issue. I searched alot on Rennlist but couldnt find someone with the same issues as me....

Cheers
M

nile13

I just looked at the car's previous records. Very weird:

Exactly 3 years ago the first owner brought it into a shop complaining of noise. Shop's comments: "Check for rattle - need to replace fan fan assembly, drive belts, air intake boot and drive belt tension sensor". So $802 for the "Engine fan assembly with bearing", $162 for tensioner,all the belts and the air duct rubber replaced. Which probably means that the noise is coming from the alternator itself, right?

Macca

Looks like you are in the lost lands with me....

Try dropping the belt form the alternator for a minute and see if the noise ceases?

Cheers
M

nile13

Ha, great idea about disconnecting the alternator belt. Will try that.

I edited my post above. I meant that the noise can only be coming from the alternator itself if the fan is presumed to be good.

Garth S

If you are running a stock two belt set up with the alt. belt alarm thingie, remove the three allen bolts , pulley halves & all spacers in order: with the belts sitting loosely on the engine pulley, hold the end of the alternator shaft ..... and spin the fan: if the fan quietly spins "smooth as silk", and no roughness is felt in the fan, the hub bearing is likely OK.
Now, spin the alternator shaft .... same deal - listen & 'feel' : you may feel the alternator brushes as a slight drag, but if a bearing is shot, it should stand out. it would be best to spin both fan and alternator shaft at the same speed ( locked together), which would eliminate the hub bearing ..... but you've already tested the latter initially.

You can also remove only the alternator belt, reassemble the pulley, tie back the "tensioner" alarm arm - and leave the alt belt standing free: with no tension on it, and no fingers nearby, the engine can be started and checked for ( lack of) noise .... the loose belt will not grab anything when not in tension.

Dudley

Hi Mike,

I have a used fan bearing you are welcome to. Also Autozone will lend you a small puller to remove the fan. I had a faint whislting sound and I ended up changing out the fan bearing and then the alternator. Turns out that a faint whistling sound is common with the 993.
Inskip Porsche has a 20% sale on Porsche parts for the next week or so if you decide to go OEM.

Macca

Yeah Dave. Thats it. A faint "hollow" sounding whistle. Like someone blowing over the mouth of an empty glass bottle. Its almost impercieveable. My mechanic suggested also that they are like that sometimes but I never noticed that noise prior to the RS pulley update. He suggested installing the single pulley and belt may have disturbed the alternator balance so thats when we stripped it out and replaced front and rear bearings. Made no difference. I can only logically assume having replaced distis, belts and disti bearing and knowing I dont have a cracked fan or anything and eliminated all othe obvious potential culprits that this "harmonic" is now caused by airflow through the fan at a potentally different frequency than efore due to the Steve Wong chip with slightly higher idle and the reduction in hardware at the front end of they airstream (i.e. from double pulley and belt to single and different profile pulley hardware. Its another of tose mysteries that will likely go usnolved but its not to the detriment of the engines integrity so be it. Frankly Im the only one that notices till I point it out to others....

Dudley

Macca, Been there, done that! I went so far as to take it to the best tech in the Norhteast and he told me, "If only you and the dog can hear it, it's nothing."