Seaflat

While driving around today I noticed a noise around 3800 to 4000 rpm. It was engine speed dependent and would stop if the revs went above this range or below. It sounded like a rattle with a high pitch. Almost like if you had a very small piece of metal in a garbage disposal, also accompanied by whir when inside the car. When I looked at the fan I noticed small scratch marks in the bottom third of the case around the fan. If I knock on the fan the pitch of the noise is smilar. I wasn’t sure if it could be some kind of bad bearing in the fan or if it was slowly getting out of line with the case. You can see the scratches in arrow “1”. (Hey it’s my first post with pictures…...thought I would try to be exact). Also, while plundering around, I noticed someone had put a zip tie around the part with the wheel that looks as if it should ride on the belt. If I remove it and let the wheel ride on the belt it screams at you at about 4500 rpms.
How much should I start warming up the visa card for?

Thanks…

mojorizing

Go here to find out how to fix a squeaky fan belt roller:

http://p-car.com/diy/roller/

if this doesn't fix if, buy a new one, it's there for a good reason.
Pelican Parts or Sunset Porsche in Oregon.

Now about the scratches on the fan housing......
Could be a bad bearing in the alternator, could be a bad bearing on the fan hub, could be loose mounts on the fan to housing flange.

You'll need to remove the belts to diagnose further. Goto the p-car.com site for that DIY. You'll need the triple box wrench to remove the belts.

Read this post:

https://rennlist.com/forums/964-forum/22652-broken-fan-yikes.html

Here's an exploded view of the alternator,etc.

AOW162435

Seaflat,
The scoring within the fan housing is most likely a sign of worn alternator bearings. As they develop play, the tension from the belts forces the rotating fan closer & closer to the lower part of the housing. If you're lucky, the damage to the fan & housing is only cosmetic. Otherwise, I've seen these blades develop cracks from the initial 'impact'.

The fan itself rides on its own bearing which rides on the alternator shaft. I just replaced my alternator and fan bearing after one or the other developed a loud screeching sound. To do this, you'll need a three-prong puller. I found a nice US-made one at Sears.

If you have the time, take the opportunity to refresh the fan - I did: Fan.

As for the belt sensor, Sunset Porsche sells these for $70.


Andreas

MisterRisky

The above comments are spot on. With mine it was the fan bearing and I replaced it with an RS hub in order to simplify things. Here's a post including a video where I did the work. If you don't mind getting your hands dirty this is certainly a DIY repair. To determine if it is the fan or the alternator just take the belts off and then wiggle the alternator shaft and then the fan. If the alternator shaft is tight and the fan wiggles then it is the fan bearing. If the shaft wiggles but the fan is tight on the shaft, then its the alternator.

https://rennlist.com/forums/964-forum/406255-fan-bearing-replaced-with-rs-hub-diy-video.html

Feel free to PM me if you have any questions.

964russ

Mine is allso producing a noise.
Goin to replace it soon.

AOW162435

+1


Andreas

Seaflat

This is the greatest group! Thanks. I keep thinking about doing it myself. I have done plenty of work on cars in the past, but for some reason the pcar intimidates me. Guess I am just scared of breaking something expensive.
I did examine the fan a bit more and there are two blades that are cracked about a quarter to a half inch. It looks like part of the surface of a blade as peeled up. Should this be replaced or as long as its moving air I am fine? Anyone have a fan for sale...before I start out on pelican and ebay?

BTW. What a great video. It did a lot for building my confidence. I have a few questions.
How is the belt tensioned on the alternator? I am used to an arrangement similar to the ac where it swings out to tighten it
So after looking at my car and watching the video, with the original set up there are two belts where the rs hub makes it one? The outside pulley is the alternator and the inside is the fan?

mojorizing

The belts are tightened/loosened by the number of shims between the sheaves of the pulley that the belt rides in. The fewer the shims the narrower the pulley is , effectively increasing the diameter where the belt rides, thus tightening the belt. Vis a versa for adding shims, making the belt ride deeper into the pulling, adding slack.

The total number of shims remains the same ,ie. the shims you don't use between the sheaves goes out side the pulley. This maintains the width of the pulley stack so ultimately the alternator nut tightens to the same point.

MisterRisky

The above response about tension is right on. You are correct about the pulleys, the outside one is the alternator and the inside one is the fan. This set up results in the fan spinning slightly slower than the alternator. I have been told that this was done to allow the alternator to spin fast enough to provide good charge for all modern accessories in stop and go traffic and the fan was slowed down to keep engine noise down. Using the RS hub results in the fan and alternator both spinning at the slower fan speed. The downside is that at idle the alternator is not putting out quite as much juice at idle as the stock set up. My personal opinion is that this is more important on a tip can than on a manual as with a tip the RPMs stay much lower. The only impact of the slower alternator speed I have noticed is that at night I can see a slight brightening of my lights when I blip the throttle off idle. I do not know if that was there before or not.

Don't let the P car scare you. I have found that it is amazingly straight forward to work on, albeit a little different than other cars.

altarchsa

+1 on the fan bearing. Happened to me.

greenjt

Hey Seaflat... where abouts are you in the Raleigh area? I haven't cracked open the alternator/fan housing but will probably need to at some point so could could be interested in lending a hand if you need one. I did replace the belt sensor a few months back - took all of 10 minutes. I'm in North Raleigh (Wakefield)

altarchsa

Just received my fan belt sensor replacement this morning. I think it was $79.00 +/-, including shipping, on eBay. If you go that route, notice there are two sellers. The less expensive one does not include shipping, so they're about the same price.

I went with Driving Source since I have ordered several items from them with success.

MisterRisky

As a total side note, if you go the RS hub route you no longer need the fan belt sensor. You will get an alternator warning light if you break the belt and have the RS hub. The fan belt sensor is needed because with the dual belts you have no way of knowing if you break only the fan belt as the alternator keeps on a chugging on its own belt.

Seaflat

Well I got called out of town on business, so I took it by the shop instead of trying it. It was the fan bearing. The alternator was the original (130k miles) so while they were in there they changed it out (no extra labor, while its out). The fan had several cracks and splits in it, so that too was replaced. They had a used one.
So.... new fan, fan bearing, alternator, found my oil leak and replaced the line, oil change - $1100
Thanks for all the help.

Greenjt -- I am over off of Wade ave. Do you ever come to the coffee klatch meetings for the hurricane region PCA meetings on Saturdays?

AOW162435

Seaflat,
PM sent.

Andreas