Can't remove the alternator fan belt ....

[sugarwood]

I had a loose fan belt on my '86 3.2. Only after ordering the 10x710 belt from Pelican did I read about the 9.5 vs 10 concerns. I will try the 10x710 belt and see what happens.

To remove the old belt, do I need to remove the AC belt?

For now, I just tightened the existing belt. It had 2 inside and 3 outside. I moved all 5 outside and the belt is much tighter. I will order the 6th shim just to be sure.

The directions say to crank the engine before final belt tightening. What can I disconnect in order to crank the engine with it actually starting up?

Thanks PP!

[HarryD]

Originally Posted by sugarwood

I had a loose fan belt on my '86 3.2. Only after ordering the 10x710 belt from Pelican did I read about the 9.5 vs 10 issue. I will try the 10x710 belt and see what happens.

But, before I can do that, it's not clear how to remove the old belt from the bottom pulley. None of the existing write ups mention this step. I can't slip it off the bottom b/c the pulley housing is in the way. Do I need to remove the AC belt that is in front of it?

If the AC Belt is in the way, you will need to remove it first and then reinstall.

For now, I just tightened the existing belt. I only found 5 shims in my pulley. It had 2 inside and 3 outside. I moved all 5 outside and the belt is much tighter. Should I order the 6th shim?

YES. Do ASAP! If there is a P-car Dealer or indy shop nearby, get one there. You need all 6 to ensure you do not bottom your Alternator nut and damage the alternator shaft. Very expensive to correct.

The directions say to crank the engine before final belt tightening. I did this, but what can I disconnect in order to crank the engine with it actually starting up? Can someone post a photo of exactly what to disconnect? (Just saying "unplug the coil" or "unplug the CD box" will not help me unless you show me where it's located, and what it looks like)

Just hit the starter to turn the motor and then turn it off. If it runs for a second or two, not a big deal.

Thanks PP!

[mo-mon]

I had a loose fan belt on my '86 3.2. Only after ordering the 10x710 belt from Pelican did I read about the 9.5 vs 10 issue. I will try the 10x710 belt and see what happens.

But, before I can do that, it's not clear how to remove the old belt from the bottom pulley. None of the existing write ups mention this step. I can't slip it off the bottom b/c the pulley housing is in the way. Do I need to remove the AC belt that is in front of it?

-Yes you can, but you have to remove the A/C belt first. Once removed, it will slip easily.

For now, I just tightened the existing belt. I only found 5 shims in my pulley. It had 2 inside and 3 outside. I moved all 5 outside and the belt is much tighter. Should I order the 6th shim?

-I would, in fact, why don't you get a new set of six.

The directions say to crank the engine before final belt tightening. I did this, but what can I disconnect in order to crank the engine with it actually starting up? Can someone post a photo of exactly what to disconnect? (Just saying "unplug the coil" or "unplug the CD box" will not help me unless you show me where it's located, and what it looks like)

- No need to disconnect anything. Just crank enough to seat the belt. If the engine starts, no big deal. Check the tension after and tighten the bolt.

I would suggest buying the Bentley book and read up on the tech info found on top of the page before you replace the belt.

[DRACO A5OG]

All 5 outside is TOO TIGHT, you might ruin the alternator bearings or worse number 8 bearing seal on the block and cause a leak, when you get the new OEM length belt and new shim, place 3 in 3 out.

If you get the shorter belt 5 in 1 out

[sugarwood]

Originally Posted by HarryD

You need all 6 to ensure you do not bottom your Alternator nut and damage the alternator shaft. Very expensive to correct.

When you say "bottom the alternator nut", are you saying it will run out of thread on the shaft and start to cut into the shaft (like a tap and die set would do?)
Can you explain why this would actually be a problem? Let's say you only use 1 shim total. You then run out of alternator shaft thread and carve new threads when trying to make the nut tight.
Could you not just remove the nut, add the 5 shims, and then tighten? With the proper shims now in place, the nut would now tighten while still on the original shaft threads, right?
I'd think the nut would not be able to reach the newly created threads (once all 6 shims are restored) Am I understanding this correctly?

Originally Posted by DRACO A5OG

All 5 outside is TOO TIGHT, you might ruin the alternator bearings or worse number 8 bearing seal on the block and cause a leak, when you get the new OEM length belt and new shim, place 3 in 3 out.

If you get the shorter belt 5 in 1 out

Recall that I am still using the original belt which must be a little stretched out by now.
The belt certainly doesn't feel too tight with teh 5 shims outside.
It has about 1/2" of play, just like the Pelican write up specifies.

I plan to remove the AC belt and install the brand new 10x710 belt.
When I do, I will start with 3 in/3 out and go from there.

All this talk about destroying the bearings and bearing seals (?) ...it's hard to tell if that's internet hyperbole or a real possibility.
Do people really destroy their engine block seals just from changing the fan belt?

[sugarwood]

For my own knowledge, I'm still curious how to disable the ignition for those times when you need to crank the engine, but don't want it to actually run. Like when checking for spark, for example.

[DRACO A5OG]

Disconnect the DME relay underneath the driver seat. That will disable the fuel pump aka kill switch on the fly.

As far as over tightening, just think about the stress you will be putting on the two points, alternator and number 8 bearing on an almost 30 year old car. I am just saying. I may be wrong but I rather error to the safe side.

Yes, 1 maybe 2 more on the outside may work but if your belt is that stretched you want to change it sooner than later. But that is what you are doing :-)

[JJ 911SC]

Originally Posted by sugarwood

... Can someone post a photo of exactly what to disconnect? (Just saying "unplug the coil" or "unplug the CD box" will not help me unless you show me where it's located, and what it looks like)

Thanks PP!

If you don't have them yet, get the Bentley and the 101 Project books.

The changing of the belt is one of the project from the 101: Pelican Technical Article: Fan Belt Replacement - 911 (1965-89) - 930 Turbo (1975-89)

P.S.: Your car does not have a CD box

[sugarwood]

Originally Posted by JJ 911SC

If you don't have them yet, get the Bentley and the 101 Project books.

The changing of the belt is one of the project from the 101: Pelican Technical Article: Fan Belt Replacement - 911 (1965-89) - 930 Turbo (1975-89)

P.S.: Your car does not have a CD box

Thanks. I do have the 101 book, and getting a Bentley manual is on my to do list.
However, the 101 book (and link) made no mention of removing the AC belt or how exactly to disable the motor.

[sugarwood]

Originally Posted by HarryD

You need all 6 shims to ensure you do not bottom your Alternator nut and damage the alternator shaft. Very expensive to correct.

Harry, now that I have completed the job, I think you have a different configuration from my 86 3.2
As you can see below, on mine, after you put on the retaining cup (pic 2) and lock washer (pic 3), it's impossible to "bottom out the alternator nut"
It can only travel a few threads to the retaining cup (which blocks the threads behind it)


Can another 3.2 owner confirm they have that lock washer in the 3rd pic?
I don't see it on the parts diagram, but it looks very original with the gold plating.

Also, the 10x710 belt installed fine.
Just might end up with a different shims config. since it's a little wider.

[JJ 911SC]

Originally Posted by sugarwood

...
Does everyone have that lock washer in the 3rd pic?
I don't see it on the parts diagram, but it looks very original with the gold plating.
...

No and its not there in either the Bentley or the Porsche Workshop Manual.

I would remove it.

[Hnichols]

[QUOTE=sugarwood;8137955

The directions say to crank the engine before final belt tightening. What can I disconnect in order to crank the engine with it actually starting up? [/QUOTE]

I think the easiest way is simply to remove the fuel pump fuse from the fuse panel in the luggage panel. (I think this would be easier than removing the DME under the front seat.)

There's a nice diagram of the fuse panel in the Bentley manual. Assuming you don't have one, I'll try to describe the location of the fuel pump fuse for your '86: There are three panels arranged alongside each other. The fuse you want is in the middle panel, which is also the biggest.

In the middle panel, the fuel pump fuse is the third one from the left (i.e. from the windshield, not the bumper) if you're facing the panel.

Just pluck it off and crank the motor.

[sugarwood]

Thanks, I'll give that fuel pump fuse trick a try.

Fuse seems more accessible than the DME which is buried under the seat.
Do you need to remove that front seat plastic trim to get access?

[sugarwood]

Does this tension seem about right?

[DRACO A5OG]

Originally Posted by sugarwood

Thanks, I'll give that fuel pump fuse trick a try.

Fuse seems more accessible than the DME which is buried under the seat.
Do you need to remove that front seat plastic trim to get access?

DME relay is that black box, push the seat forward, look behind and under the seat, reach in and pull it off.

[DRACO A5OG]

Originally Posted by sugarwood

Does this tension seem about right?

You made your video PRIVATE, we can not access

[86 911 Targa]

[HarryD]

Do what ever you wish, after all it is your car. That said, things not what they seem. Make sure you have 6 shims.

Here are some thoughts on fan pulley assembly by the late Grady Clay (after all, what would he know?):

Originally Posted by Grady Clay

There is a fine line between too loose and too tight. With a new
belt, err on the too tight side, they will stretch.

The belt/pulley arrangement was easy prior to ’74 with the large
shims. As the shims got skinnier in later years, it became more
difficult to get them in place correctly. That was made even
worse with the air pump drive off the outer pulley half. Expect
to use up a shim or few every time you replace the belt.

You should keep the shims between the pulley half and the fan in
perfect condition. They determine the tension in the belt and
control the runout in the outer pulley half. As said above, the
outer shims are just storage and prevent the nut/cup washer
from running out of threads on the alternator shaft.

A good first step is to tighten the pulley with all like new shims in
between the halves but not the belt and measure the runout of
the outer half. A bent or damaged outer half is very common.

Next would be to inspect the hub of the fan and the double-D
bore of the outer pulley half. It is very common for these to have
been loose or mal-installed sometime in their life. A cracked
pulley half should be replaced. The common damage is where
the outer pulley half can rotate slightly on the hub when lightly
held in place (finger tight) with the nut and cup washer. Hold
the fan still and rotate the outer half back & forth.

Inspect the cup washer for damage. It is common for them to
become bent in at the center from someone over-tightening the
nut. Replace it if there is any damage or deformation.

While everything is apart, check the nut fro free turning on the
threaded alternator shaft. Check for rounded off hex. Replace
if necessary. A new nut is far less expensive than a galled
alternator shaft.

Porsche is very specific about the fan pulley shims. For
the “Turbo fan” and many others with 1.6:1 and 1.8:1 ratio,
they want you to set it to spec, run it for a while, and then move
one more shim from between the pulley halves to the outside.
In the Technical Info booklet (4591.21) for the ‘80SC it
reads: “Tighten belt as usual (10-15 mm deflection). Then
reduce the number of spacers between the pulley haves by one
(ca. 5 mm belt deflection.”

For the ratio conversion the new longer fan belt is 9.5x725
(999.192.097.50) available from our host. Remember to replace
your spare belt also.

I like to run-in my spare belt also. I let it stay in the tool kit in its
natural shape – not bent to fit the pouch. It is good practice to
also carry a spare outer pulley half (930.106.209.02), the cup
(911.603.428.01), and six extra shims (930.106.564.00). (These
P/Ns may not be applicable to your 911.)

When assembling the pulley half, make sure you don’t pinch any
shims (it is easy to have them get out of place) and the pulley
half runs true when tight. Never use a wrinkled, bent, or
damaged shim. With all these bits & pieces in your hands, make
sure you don’t cross-thread the alternator nut. This really can
use two sets of hands. Practice with the belt off. As you tighten
the nut, rotate the fan so the pulley half is tightened evenly and
the belt moves out to its running position. It is very easy to
bend the outer pulley half or install it with a wobble (too much
runout). Never use an air wrench to tighten the nut – undoing
the nut is OK.

Make sure the holder tool is in good condition. The same is very
important for the wrenching provision on the pulley. I have seen
some aftermarket and home made tools that are superior to the
Factory tool-kit versions. Never let the tool slip off while
tightening – that will damage the pulley and tool.

If you ever see rust coming from between the pulley halves, that
is a sign of a loose pulley half that is wobbling on the hub.

A too loose belt will slip and “squeal” when wet and you
accelerate free rev the engine. Of course it can slip and
overheat the belt and other parts.

A too tight belt will put undo stress on the alternator bearings.

For something seemingly as simple as a fan belt replacement the
devil is in the details.
IMAGE FanRatio02.jpg “
"
© Dr. Ing. h.c. F. Porsche A.G.

Best,
Grady

Originally Posted by Grady Clay

Here is a used outer pulley half that is in reasonably good condition.

Wear usually takes place on the four corners of the flats. I have
shaded red one corner but all four (red arrows) will be the same.
This is from the pulley being run while loose – a common occurrence.
Anything other that like new should be replaced. It is also
common for the pulley half to fracture with a crack starting
at the corners (red arrows).
IMAGE: FanPulleyHalf01a_IMG_0589.jpg


When the outer pulley half has been allowed to be loose or
wobble the fan hub can also be damaged (red arrow below).
Inspect carefully for this notch in the hub. If severe as this,
the entire fan needs to be replaced – very expensive.
IMAGE: FanPulleyHalf02a_IMG_0596.jpg




The cup shaped washer commonly becomes deformed with the
center pushed in toward the fan. This has the same effect as
running less than six total shims. The nut bottoms out at the
end of the threads on the alternator shaft. The result is the nut
is tight but not clamping the pulley halves together. The outer
half is loose (or at least not clamped tightly) and everything
gets ruined. Replace the cup washer if deformed at all. It is
cheap compared to the alternative.

I’ll see if I can find some ones in disrepair.

Best,
Grady

Originally Posted by Grady Clay

Here is the cup washer under the alternator nut and some shims.
Note the damaged shim.

The shim wasn’t fully centered on the hub and the part at about
10 O’clock caught on the hub. The entire left half of this shim
was pulled under the cup part and not seated under the
perimeter. Note the mark (red arrow) where the perimeter
of the cup washer was. This left the outer pulley half clamped
unevenly and probably caused wear on the pulley and fan hub.
Not good.
IMAGE: FanPulleyShims03_IMG_0937.jpg






The good cup washer from above is now on the right and another
(bad) one is on the left. There is about three shims clearance
(red arrow below) between the straight edge and where the
alternator nut sits. This puts the nut dangerously close to
bottoming its threads and not properly clamping the outer pulley
half in place. This can lead to severe damage to the fan hub and
outer pulley half as in the above post. Note the good cup washer
is flush (green arrow) with the straight edge.
IMAGE: FanPulleyCupWasher02_IMG_0939.jpg


It is possible to lay the cup washer on an anvil, open side up, and
straighten it using an appropriate size socket and a big hammer.
This only works once and only with one deformed about as
much as the bad one above. Better to just replace it.

Best,
Grady

[HarryD]

Originally Posted by sugarwood

Harry, now that I have completed the job, I think you have a different configuration from my 86 3.2
As you can see below, on mine, after you put on the retaining cup (pic 2) and lock washer (pic 3), it's impossible to "bottom out the alternator nut"
It can only travel a few threads to the retaining cup (which blocks the threads behind it)


Can another 3.2 owner confirm they have that lock washer in the 3rd pic?
I don't see it on the parts diagram, but it looks very original with the gold plating.

Also, the 10x710 belt installed fine.
Just might end up with a different shims config. since it's a little wider.

Lock washer is a PO Kludge. do it right. Get 6 shims and a new cup washer. Cost? About $25.

Cost of a new Outer pulley? About $100.

Cost of a replacement alternator because you buggered the shaft? $685.

Pay me now, pay me later.....

[sugarwood]

Harry, thanks for digging up the Grady archives regarding this subject. What a great forum, and I can see why Grady is so missed here.

I will add the 6th shim when it arrives, but the various damage pictured above is not due to a missing shim. It's due to very sloppy reassembly.
When replacing the pulley, one should crouch down to eye level, and make sure it is fully seated on the rectangular notch.
It also helps to be down at eye level to verify the shims are seated properly under the cup before replacing the nut.
If any shims slip off and are not seated flush, the pulley will not seat right, and the pictured damage to the shaft makes sense.
Always verify the pulley is not wobbling after reassembly.

I don't feel there's any need to replace the shims or cup washer since mine are perfectly intact.
The cup washer would have to be totally caved in to allow the alternator nut to actually bottom out before fully tightening the pulley.
I think you'd need to use an impact wrench to get such a thick piece of metal to bend in like that!

I don't see any downside to the split lock washer. In fact, it's sensible for a few reasons.
1) It better secures the nut.
2) It would theoretically help prevent bottoming out of the alternator nut, if you did indeed have a caved in cup washer.
3) Since it has a larger diameter than the alternator nut itself, it may help prevent cup bending if you overtighten it, since pressure is distributed towards the outer edge.

Thanks for the info! It's been nice to talk through this one.