How loose should the fan be?

[High Life]

Ive done a quick search but hard to find anything (or I'm using the wrong search words).

I have an 11 blade fan and if I put my hands on it and wiggle it (back and forth) - I have quite a bit of play. Guessing 1/8 of an inch by feel..

Belt is tight- but not too tight..

Just wondering if this is an issue (alternator not tight or something?) bearing bad?

Any guidance would be appreciated.

[Bob Kontak]

1/8th inch in the linear plane is tight. 1/8 inch in the lateral plane is not correct. What is moving?

[Trackrash]

And it isn't rubbing or making noise like the alternator bearings are shot?

I wouldn't drive the car until I had this figured out.

[High Life]

Originally Posted by Bob Kontak

1/8th inch in the linear plane is tight. 1/8 inch in the lateral plane is not correct. What is moving?

Holding 9 and 3 - pushing with one hand - pulling with the other - lateral plane..


just in case Im misunderstanding Bob.. heres a video

https://youtu.be/MLQG994t1k0

[High Life]

Originally Posted by Trackrash

And it isn't rubbing or making noise like the alternator bearings are shot?

I wouldn't drive the car until I had this figured out.

Ok - wont drive..

I should pull belt and rotate to see if I hear anything?

Take a look at the video Trackrash - thats the play Im talking about..

[Rawknees'Turbo]

Just looked at your vid - is that movement of the fan on the alternator shaft or is the alternator shafting moving as well (along with the fan)?

[High Life]

Originally Posted by Rawknees'Turbo

Just looked at your vid - is that movement of the fan on the alternator shaft or is the alternator shafting moving as well (along with the fan)?

I believe the alternator shaft is moving with the fan - Ive never had one apart , so Im kinda guessing what you are asking. The nut that holds the fan belt pulley is on the shaft and when I wiggle the fan - the pulley, shaft, nut all move with the fan. Does that make sense?

[Trackrash]

Kind of hard to see where the movement is occurring. However, it seems to me that if the alternator bearings were that loose you would hear it. Hopefully the alternator itself is loose in the shroud. Are you sure it isn't the fan loose on the shaft? Can you pull the fan off the shaft if you remove the nut?

[75 911s]

That play is all wrong. Remove it. Fix it and reinstall before driving imho.

Potentially the woodruf key is jammed in wrong or not aligned properly. Another thing to look for is the housing itself is cracked where it supports the alternator / fan.

[High Life]

Originally Posted by Trackrash

Kind of hard to see where the movement is occurring. However, it seems to me that if the alternator bearings were that loose you would hear it. Hopefully the alternator itself is loose in the shroud. Are you sure it isn't the fan loose on the shaft? Can you pull the fan off the shaft if you remove the nut?

I just went back out and looked - the whole assembly moves - fan, pulley, belt - so Im assuming the shaft is moving.

From your comment - It sounds like the fan should not wobble like that? So I should not drive it and pull the fan / alternator and investigate..

Heres a closer video

https://youtu.be/qxdBFqnWCAI

[High Life]

Originally Posted by 75 911s

That play is all wrong. Remove it. Fix it and reinstall before driving imho.

Potentially the woodruf key is jammed in wrong or not aligned properly. Another thing to look for is the housing itself is cracked where it supports the alternator / fan.

Yeah - thanks - that confirms it shouldn't act like that.. Being a bit new to this model, I wasn't sure and I couldn't remember it moving that easily..


Thanks for all the input.. I was reading through threads, Bentley and 101 and being able to ask you guys directly helped immensely..

High Life is on me..

[iwhelan]

When I purchased my '87 911, there were random clunks from that area which turned out to be bad alternator bearings. The whole shaft with fan, belt, etc were able to move fore and aft. A new alternator cured the problem.

[High Life]

UPDATE:

Pulled the fan / alternator and this is what I found:

https://youtu.be/AHpsuqZMhbY

(I could push / pull shaft inside the alternator - 1/8 of an inch or so..)

The back part of the alternator housed a cap that was laying on the engine.






Once I put the cap on - I have no play.. How integral is the cap? Is it just a dust cap or does it help seat the bearing?

[Trackrash]

That shaft should be able to spin, but not move in any other direction. The plastic cap is only a dust cap and has nothing to do with the shaft's location.

[Bob Kontak]

Originally Posted by High Life

Once I put the cap on - I have no play.. How integral is the cap? Is it just a dust cap or does it help seat the bearing?

I have to say no but I cannot confirm. I know the crankshaft should be checked for front back movement with a dial indicator. Just a scant few thousandths of slop allowed. The alternator spins faster than the crankshaft.

Thinking end-play is not correct. Would not have popped the cap off.

You do not have to go nutso with a $500 high output alternator but that's your choice.

Thank you for your work to present a clear picture of your problem.

Get the internal voltage regulator vs external. Just a little dremeling in the air diverter to fit. In case you do not have now.

[High Life]

Originally Posted by Trackrash

That shaft should be able to spin, but not move in any other direction. The plastic cap is only a dust cap and has nothing to do with the shaft's location.

Ok - That makes sense to me..

Originally Posted by Bob Kontak

I have to say no but I cannot confirm. I know the crankshaft should be checked for front back movement with a dial indicator. Just a scant few thousandths of slop allowed. The alternator spins faster than the crankshaft.

Thinking end-play is not correct. Would not have popped the cap off.

You do not have to go nutso with a $500 high output alternator but that's your choice.

Thank you for your work to present a clear picture of your problem.

Get the internal voltage regulator vs external. Just a little dremeling in the air diverter to fit. In case you do not have now.

Internal regulator...hmmm.. still thinking on this.. how does the wiring end up?

Any thoughts on brand? BOSCH or Valeo?

Or should I see about having it rebuilt? We do have a small re builder here in Des Moines I could try..

[Trackrash]

You might check the price on stock replacements, then see what it would cost to have yours rebuilt. Those Marchel units tend to be long lasting, so a rebuild may be the way to go.

[timmy2]

Originally Posted by Trackrash

You might check the price on stock replacements, then see what it would cost to have yours rebuilt. Those Marchel units tend to be long lasting, so a rebuild may be the way to go.

^^^^^ this, and it is a lot easier to change a remote VR when it fails.