ble2011

I replaced my alternator and fan/hub bearing last year. I'm hearing an odd noise and suspect one or the other is bad again. Either my parts were defective or I had the belts too tight and ruined them. The question I have is, can I run the engine for a short time with all the belts removed? I can then narrow down the issue to the alternator or fan hub instead of something else.

P-daddy

I just recently went through this. I'd start with removing all belts and spin the shaft to isolate where the noise is from. You want to spin the fan to test its bearing then hold the fan blade to spin the alt shaft.

ble2011

I'm comfortable isolating the issue to the fan bearings or the fan hub bearings as you described. But, seeing how everything is so new, and the noise right now is very faint, I thought I may not be able to feel if there is a problem. If I could remove all belts and just start the car, if I do not hear the problem, I can be assured it's located in the alternator bearings/fan hub bearing or even air conditioner (as that's one of the belts I'd be removing as well).

AOW162435

Take a zip-tie and strap the belt sensor arm so the wheel no longer touches the fan belt.

Start the engine. If the noise is gone, the bearing inside the sensor wheel is failing.



Andreas

JB 911

^ Some good suggestions.

Heres another one. Examine the inside lower surface of the fan shroud for sratch marks with a flashlight. To determine new from old marks, sharpie across them and go for a drive.

ble2011

All good suggestions. But, the alternator is new, the fan and fan hub is new, the belt sensor is new. I even had the shroud powder coated. There are no scratches on the fan shroud. What I really need to know is if I can run the engine with the belts removed.

P-daddy

Yes you can for a short duration. Are you running the engine without belts to isolate the noise?
BTW, small chance but even new parts have known to fail.

Mike J

Short is really short - like a minute or so. Depends on if you are driving or just idling, ambient temperatures, etc.

ble2011

Yes. I want to isolate the noise. If I run without belts and still hear the noise, I know it's not any of the parts I just replaced.

P-daddy

Well, what did you discover?

six gun

ble2011

I won't have any time until this weekend to look at it. I'll post what I find.

ble2011

Well I finally got around to working on the 993. I found the alternator bearings are shot. I replaced the alternator last September. The belts were definitely not too tight. I've only driven the vehicle maybe 3 months (it's stored in the winter). I have a warranty, so replacement is under way. However, I've been reading about rebuilt Bosch alternators and my fear is the next one is probably not going to hold up either. Not much I can do at this point, but to install the next one and cross my fingers. Sure wish we could buy quality replacement parts.