My alternator fan started rubbing on the housing today, need help with diagnosis...

Kemo · 12-31-2008, 02:29 PM

I noticed a high whiney sound that started just today. I was only about 1/10th of a mile from my house so I got home pretty quick. I lifted the hood when I got home and noticed these scratches. I started the engine and kinda pushed and pulled on the housing and was able to increase/decrease the rubbing depending on which way I pushed.

So, my question is this: What do I have to replace to get this lined up? The whole alternator or just some bearings. Im not sure how all of that is put together in there. Here is a quick pic.

Gogar · 12-31-2008, 02:37 PM

Just pull the whole fan/housing/alt assembly out.

It's possible that the fan housing has cracked, (bummer) or maybe a nut that holds the alt in the housing has just backed off and needs tightened (easy.) Sometimes the holes in the air deflector will become enlarged as well and the plastic breaks, which will cause the alt to be a little loose in the housing as well.

Mitch Leland · Mitch Leland's Garage

I would remove the alternator belt and see if the alternator is lose in the housing, maybe the alternator bearings have given up. Best to back up and start from scratch by releasing the tension on the alternator. I'm sure with the wear that's going on the problem will be pretty evident.

Zeke · 12-31-2008, 02:58 PM

I agree with ML seeing where the wear is.

john walker's workshop · 12-31-2008, 06:32 PM

i see this a lot with cracked housings.

Laneco · 01-01-2009, 06:51 AM

Remove the alternator and fan housing assembly. That way you can thoroughly inspect the housing for cracks and the alternator for play. Most likely problem is loose bolts or cracked housing unfortunately. I had a housing from an 82 engine that had 9 cracks in it. Rather expensive piece of junk.

If you're lucky and it's just loose bolts, clean up and paint the fan and housing before you put them back in. Easy to do and really looks alot nicer than what you've got going on there now...

angela

Gunter · Gunter's Garage

+1 with the above; remove the housing and inspect for cracks etc.
If the alternator has a lot of time on it, have it rebuild.

Minor cracks in the housing can be repaired with JB Weld by using a Dremel tool with a small router-bit to clean the area around the crack first, then apply JB.

If the support fins are cracked right through, try and find a good used one.

Do not over-tighten the belt to stress the housing fins.
IMHO, a lot of cracks develop from tight belts, vibration and old age.

Charlie V · Charlie V's Garage

Mine started to rub because of worn bearings. Also the internals rubbed and shorted out.

I took it to an electric motor rebuild shop and they worked their magic - new bearings and rewound the internals for $125. Has worked perfectly for the last 1.5 years.

Much better than the previous $450 for the POS rebuilt replacement - not from our host.

Kemo · 01-02-2009, 06:50 AM

thanks for all the advice and insight. Im going to try and pull the alternator and surrounding housings tonight for inspection. Ill post some pics of the carnage. hopefully it will be a $imple fix.

"while im in there", is there anything else I could address as far as preventative maintenance of that area?

Kemo · 01-02-2009, 06:55 AM

oh...and one more question...

does the housing have a locator pin or anything under there that sets the location of the timing mark? If not, I guess I will just set the motor to TDC before removal so I have a reference.

j_mancini · 01-02-2009, 07:06 AM

Yes, there is a slot that keys with the bottom of the fan housing.

Aurel · Aurel's Garage

I had the exact same symptom, and it was cracked fan housing. It is either that, or worn out alternator bearing. If you remove the belt, worn out bearing should be easy to test by axial play of the fan. My bet is on a cracked housing though (my car is also a 78SC, same age magnesium fan housing...).

yelcab1 · 01-02-2009, 09:05 AM

I had both cracked housing in 3 places, and bad bearing for the alternator. I tried to get the mag housing welded but nobody around here does it so I just reused it. I did have the alternator rebuilt, for $125 and confirmed that the bearing was toast. Have yours rebuilt. It is only 30 years old.

k9handler · 01-02-2009, 09:12 AM

I had this happen on the 3.6...it was the bearings within the Alt...when I pulled it you could see the damage on the shaft itself. Replaced the Alt and issue was fixed.

FPB111 · 01-02-2009, 05:59 PM

Vertex offers housings, the fit quality was variable in the beginning. I know of two folks that have used them. One fit no problem 1980SC, one (1982?) had some problems with the first returned it and no probs with the second.
http://www.**********.com/ShowItem/197769%20Porsche%20Alternator%20Fan%20Housing%20%2 0Upgraded%20Aluminum.aspx
Do a search here and get some opinions.

yelcab1 · 01-02-2009, 06:06 PM

Quote:

Originally Posted by FPB111

Vertex offers housings, the fit quality was variable in the beginning. I know of two folks that have used them. One fit no problem 1980SC, one (1982?) had some problems with the first returned it and no probs with the second.
http://www.**********.com/ShowItem/197769%20Porsche%20Alternator%20Fan%20Housing%20%2 0Upgraded%20Aluminum.aspx
Do a search here and get some opinions.

That is a $450 fix, plus an alternator for $150, and you are up to $600 for a car that is maybe ... $6500 in this economy.

FPB111 · 01-02-2009, 06:47 PM

Kemo,
Listen to yelcab1, don't spend $$ on that 30 old used car. Just pack it up and send it out here to NJ. I'll take it off your hands for no charge.
You know that the next time a major service, timing belt, belts, water pump, pulleys, filters,fluid, etc is due on his 20 yr old 328, ($10k dollars for a car that is worth only ~$50k in this market) he is going to push it out on the front lawn and fill it with flowers.

yelcab1 · 01-02-2009, 07:39 PM

Quote:

Originally Posted by FPB111

Kemo,
Listen to yelcab1, don't spend $$ on that 30 old used car. Just pack it up and send it out here to NJ. I'll take it off your hands for no charge.
You know that the next time a major service, timing belt, belts, water pump, pulleys, filters,fluid, etc is due on his 20 yr old 328, ($10k dollars for a car that is worth only ~$50k in this market) he is going to push it out on the front lawn and fill it with flowers.

I tune my own Ferrari. It only costs $1000 for the parts. Besides, my point is to fix the cracked housing with less expensive means before buying a new aluminum one. JB welding works, and it's only $10 a tube.

Kemo · 01-03-2009, 02:49 PM

Ok...here is a quick update.

The weather was great here in Austin topping 80 deg F this afternoon. It made for a good day in the garage.

I was able to remove the fan housing with the alternator and fan together as a unit. I took note of where each wire was before totally removing. I was surprised to find a wire not attached to anything at all just hanging there. It was the black one.

I took the alternator housing over to a table and checked out the back. It appears that there were only 2 bolts left holding the unit in place! Somewhere down the line, i think this alternator was replaced, and not very well. I checked the housing for cracks or anything out of the ordinary. I was pleasantly surprised to find it damage free. This was a big relief given the outrageous price of the housing.

Since I have everything out, I figured I would clean it all up as best I could. I removed the fan and alternator from the housing then removed the fan from the alternator. While I was checking the back, I noticed that the Square piece had some plastic that was damaged and falling off. So I will be sending this one out to be rebuilt. What need to know is what type of alternator is this? There are no part numbers anywhere. Here is a pic from the back and from the front.

And here is a pic of a stamped logo of somesort in the casing:

Any help identifying which alternator this is greatly appreciated. With this in mind, does anyone know of a good place to send my alternator to get it rebuilt?

Now for the final mystery, I have 3 connections on the back of the alternator and 4 wires. I can account for all but the black wire. Does anyone know what might be the issue here with this spare wire? I dont have a clue. Do I have the correct alternator for my car?

As always, thanks for all the helpful insite.

Kemo · 01-03-2009, 03:22 PM

Since I had the whole day, I spent some time cleaning up the old fan housing and fan. I hit the fan housing with some flat black high temp BBQ paint. I then cleaned up the fan and sprayed it with a silverish aluminum color high temp enamel. I have heard that it probably wont last very long, but I just had to bling it up "since I was in there".