So whats really happening when the fan scrapes the housing?

Sunroof · 01-10-2006, 10:16 AM

I was adjusting my idle last night and heard several faint metallic ticks and at first thought it was the distributor or a fuel injector. I noticed some fresh metal scrapes in the lower left portion of my fan housing lined up in lines. I can only assume its one of several things (alternator bearing, fan blade housing bearing(?), or offset belt).
Looking closely at the belt, their is a very slight (hardly noticeable) wobble I can see watching the locking nut. Am I on target, or could this be something deeper in the housing?

Suggestions?

Thanks
Bob
73.5T/CIS

jhelgesen · 01-10-2006, 10:23 AM

I had this happen on my 3.0, had to tighten my alternator retaining nuts.

Sunroof · 01-10-2006, 10:26 AM

Thanks John.
I had the alternator rebuilt awhile ago. What is the procedure for getting in? That is getting the fan shroud off to get to the bolts are are they accessible thru the fan? Would it help to try the belt retensioning first?

Bob

dan79brooklyn · 01-10-2006, 10:37 AM

Mine was almost rounded away and was wobbling a lot, but the fan did not touch the housing only looked and sounded funny. The pulley hole for the bolt was rounded off and a replacemt was needed...

Best of luck.

vash · vash's Garage

i am with john on this one. your fan/alt is possibly installed with a "skew". you need to make sure all the nuts in back are even tightened.

Sunroof · 01-10-2006, 11:01 AM

Can anyone provide a schematic or procedure for tightening the alternator bolts? Are they hard to reach? Do I have to remove the shroud? I never messed around in this area before.

Thanks
Bob

Joeaksa · 01-10-2006, 11:03 AM

Also can be bearings going South. Worth checking as new fans are not cheap nor readily available.

jhelgesen · 01-10-2006, 11:10 AM

take off the fan belt, then disconnect the fan strap. There are one or two bolts holding the shroud to the fan housing too. Fan housing and fan will come off as a unit, wires attached. Take either a 8 or 10mm (don't rememeber which) and tighten the 6 nuts in a star pattern. Might even put some loctite on them. Check to see the lock washers are in place.

emcdan · 01-10-2006, 11:28 AM

Along with what John said...after removing the fan belt, spin the alternator by hand and listen for the scraping. Also, see if there is any obvious wobble in the shaft. Even new bearings can go bad.

Even a slightly bad bearing can cause the fan to scrape the shroud. Mine made that same noise one day and the next day it made a God awful screech.

Hopefully an adjustment will help.

Good luck Eric

Jim Sims · 01-10-2006, 11:39 AM

Possible causes:
(1) failing plastic retainer for back (in forward position relative to car) alternator bearing,
(2) alternator bearings are failing again,
(3) alternator securing bolt /nuts are loose,
(4) fan hub has been damaged (incorrect use of belt tensioning shims and washers) and fan now has run out,
(5) cracked fan shroud (shroud is what alternator is bolted to) - cracks can come from excessive belt tension, overtightened securing strap or band or metal fatigue (old age),
(6) fan shroud is loose; check securing strap or band.

Shroud and alternator must come out to address 1-5.

FrayAdjacent911 · 01-10-2006, 11:53 AM

I just reinstalled my fan and shroud, but haven't gotten Stinky running yet. I noticed that after I installed it, ONE of the blades was making slight contact with one of the coil mounting stud ends. Only one of the blades. I filed down the stud a little bit, and got it to spin freely.

Would it be a good idea for me to remove the belt and recheck the alternator nuts at the back of the fan (Front of car)? I think I should... I don't want to risk having it wobble and cause problems later on!

Tom F2 · 01-10-2006, 12:50 PM

In the case of my 3.0 Turbo, it was a cracked fan shroud.

twin plugged targa · twin plugged targa's Garage

fan shroud was cracked on my old 86ragtop I guess by overtightening by PO?

Tom F2 · 01-10-2006, 01:34 PM

The fan housing on my car was cracked because, I believe, the prior owner pinched the ground wires to the alternator between the housing and the crankcase. The pinched wires cocked the housing slightly, so the housing was not evenly supported around the perimeter and presumably distorted enough to crack. That's what I found, at least.

harold12750 · 01-26-2006, 01:01 PM

I installed a rebuilt alternator 4 times because i had a similar problem.
instead of using the plastic cooling vane as a spacer ,I put the nuts on
first then the plastic thingy against the nuts and then more nuts to hold
the cooling vane on.works great! no noise!

jabb · 01-26-2006, 02:01 PM

Disconnect the Battery If you are going to start to remove the Alternator to check or tighten the bolts.

Look here for the Tech Article Click_Here

Tall02 · 02-06-2006, 04:46 PM

I had a similar problem and found one fan blade had a small split which flared out right at the end. This made contact with the stationary housing. I pulled off the fan and cleaned the split. Pressed it together and used an apoxy weld. Filed smooth and bingo. Spins quiet like a champ. It looked like a small stone may have come up through the cylinder fins and dinged the blade.