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HomeTech Articles > 993 Technical Article:

Pelican Guest Technical Article
Permission to publish this article is provided generously by
Robin Sun at
Be sure to visit his site for loads of 993 info!

How to replace your V- belt
This DIY is contributed by Tom Trawinski
Updates made by Robin on June,2000 including pictures.

Difficulty scale (10 being hardest): 6

Tools needed:  Adjustable wrench (or 24mm or 15/16" open end wrench)
                         Special Porsche 12 point allen tool part#999 571 052 02:

                         13mm socket & wrench
                          3 to 6 inch extension
                          5mm hex bit 
                          4mm allen key or hex bit (96+ uses a 8mm socket)


Complete belts listing: (from Porsche parts catalog)      

Part number Description Size Engine group
999 192 338 50 Fan belt 9.5 x 776 mm
999 192 343 50 Fan belt 9.5 x 760 mm M64.60
999 192 343 50 Alternator belt 9.5 x 760 mm M64.06/07/08
999 192 373 50 Alternator belt 9.5 x 753 mm (with pulley update kit) M64.60
999 192 372 50 Alternator belt 9.5 x 757 mm M64.60
999 192 363 50 A/C compressor belt 13 x 1083 mm Same for all 993


(1) Start with the A/C belt.  Loosen A/C bracket with 4mm allen key.  For 96+ 993s the A/C bracket uses a 8mm bolt.  And make sure the lines can move back & forth freely.


(2) On the right side of A/C compressor prior to loosen the adjuster locking bolt with 13mm wrench use a 13mm wrench turn the tension adjustment bolt a couple of turns first and thenloosen adjustment bolt lock nut with the wrench.   Proceed to loosen the tension adjustment bolt few more turns. 


(3) Using 13mm socket with extension to loosen the two bolts under the A/C lines (one is short, one is very long).  Remove the other three bolts that hold down the compressor.  Be careful not to lose the square nuts, put yours hand underneath the square buts to prevent them from falling.  Lift the compressor off its base just few cm toward to the center of the car once all the mounting bolts have been removed.  Lift the belt from the pulley first, then pull it off the crank pulley.


(4) Using the Porsche special tool# 999 571 052 02 and a 24mm wrench to loosen the alternator shaft bolt.  The special tool holds the shaft in place to prevent it from spinning while you break the nut free. 
Remove the nut, shim (if any), outer spacer, and outer pulley half.  Slide belt towards you & remove from crank pulley.  If there are any shims in between the pulley halves, remove them (but remember how many there are).  Pull inner pulley half and inner spacer off.  You will now have access to fan pulley.  Prior to the start of this process it is a recommended tip from John D II (NH) to place a rag under neath the pulley work area to prevent any bolts and parts fallen into the bottom.


(5) Remove the three bolts with a 5mm hex bit and ratchet.  Do not use allen keys as the heads can strip very easily.  Spray a little penetrant on bolts to help loosen them up.   A trick to do to prevent the 5 mm allen nuts from stripping is to break the nut loose by hitting the ratchet handle with a hard jolt.  After removing them make note of how many shims are on the outside of the pulley and the little white tab (the white tabs only exists on 95 993s).  The outer pulley half  and shims have a small index hole that the white tab fits through.   You will need to line it all up when installing.  Pull the outer pulley half off.  To get the belt off slide the wheel sensor to the left.


(6) Get ready to install the new belts.  

(7) Install fan belt on to crank pulley and center top part over alternator shaft.  (If the belt do not fit easily into the crank pulley, use an long object like a long 3/8" extension to push the belt into the crank pulley.)  Be sure to lift up the fan  belt follower to avoid breaking it.  Line up white tab with holes and slide outer fan pulley & shims on to the alternator shaft as far as it will go.  Thread all three bolts by hand.  To tighten the pulley squeeze the belt at the midpoint between the crank & fan pulleys.   Tighten each bolt a little, and repeat a few times until bolts are tight w/o crunching the belt.  You can line it up by pulling the belt either way a few times.  Do not force the bolts tight.  Use finesse.  When the bolts are tightened up crank the starter two or three times to get the belt to sit correctly (try not to start the engine).  Check the tension of the belt.  If it is too loose or too tight, add shims (to loosen) or remove shims (to tighten). 

(8) For the alternator pulley the factory has an updated kit to prevent premature wear of the belt.  The new part in the TSB is 993-106-268-01 and costs about $58.00USD with PCA discount.  A new pair of shims are also listed in the bulletin so pick them up too (about $1.50 each).  Shims are used to adjust the belt tension.  The general rule of thumb to remember is: less is more (fewer shims is more tension) and vice versa.  If you look at the pictures the newer pulleys are larger in diameter, have a slightly less curve, and have the spacers built in.  Delete the old pulleys and spacers.

(9) Slide one half of the pulley with the smooth side facing out.  Place alternator belt over crank pulley and center it over shaft.  Slide other pulley half on with smooth side facing in as far as possible and thread the 24mm nut (15/16" nut) by hand.  Use the adjustable wrench & torx bit until tight.  Follow the same procedure to tighten this as the fan belt pulley.  Remember a little finesse is needed here.  After it is tight start engine.  Make sure the fan & alternator dashboard light go out, and then check that the belts are turning smoothly.  Shut off engine and check the belts tension.  They should deflect about ¼ inch.

(10) Install the A/C belt over crank pulley, then over the compressor.  Slide compressor to right and start tightening the adjustment bolt.  Do not tighten all the way yet.  Insert the three long mounting bolts in their holes.  They should slide all the way down.  If they don’t then tighten up adjuster bolt until they are completely inserted.  Place square nuts on each end and tighten up.  Check belt tension, it should feel tight and deflect about ¼ inch at most.  Adjust it by loosening up the three long bolts and turn the adjustment bolt until desired belt tension is set.  Tighten all the long bolts, the short bolt, then lock the adjustment bolt in place (hint:  loosen it up slightly, tighten inner nut by hand, and tighten bolt).  Tighten the A/C lines bracket.

(11)  Start the engine and turn on the A/C.  All belts should turn freely & smoothly.  Place old belts in your trunk as spares.  Take the car out for a test drive.  When you get back inspect belts to make sure all is OK.

Belt tension tips from Skip
Porsche part number 000 721 957 40 (and about $40 as I recall) gets you special tool number 9574, the Gates "Krikit" V-Belt Tension Gage (which is probably $10 at an AutoZone near you).  Of course, your $500 Porsche factory manual set provides 3 full pages of instructions for using the thing, whereas you only get 1/2 of a Xeroxed page printed in 1981 with it - so I guess we shouldn't complain too much.  It's a rudimentary gage about 4" long that measures in both foot/lbs and kgs. Porsche gives their specs in "increments" of the kg scale.  Per the manuals, these are the belt specs for both the 993 and the 993 TT:  Alternator and fan belts: When fitting new belt: 23-35 increments cold, 28-40 once run for 15 mins/10 miles Checking used belt: 15-23 increments cold, 20-28 at op temp. Adjustment not needed unless below 15/20. A/c belt : 30-35 increments at op temp 

Hope this helps Skip '96 TT 

When I took my belts off the 2nd time to check for squeaking noise I accidentally stripped the alternator shaft since I was using the incorrect tool to hold the shaft still.  If you are interested to see how I fixed the stripped alternator shaft 
click here

Comments and Suggestions:
Not sure Comments: Can you slide the belts on over the pulleys and turn motor over till there on 1998 993
April 14, 2017
  Followup from the Pelican Staff: You risk damaging the belts doing it that way. - Nick at Pelican Parts  
Steve Comments: Do you have to remove the 3 compressor bolts? Why can't you just loosen them to slide the compressor over to the left to remove the belt as stated in the Factory Manual. Not much room to get the square nuts back in place unless you got mini me hands.
April 8, 2016
  Followup from the Pelican Staff: It has to be removed. - Nick at Pelican Parts  
993ninja Comments: Does anyone know what's the part number for the 8mm bolt and washer for the bracket ?
November 14, 2015
  Followup from the Pelican Staff: I’m not the best with part numbers.

Give our parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
gsliz Comments: Sorry when I said I could not get the 10mm to fit I meant that the alternator shaft - mine seems to be between 9mm and 10mm!
May 26, 2014
  Followup from the Pelican Staff: Try a standard size. Someone may have jammed the wrong size on. - Nick at Pelican Parts  
aussie Comments: How much clearance should there be between the alternator fan pulley and the alternator fan housing on my 993?
May 7, 2014
  Followup from the Pelican Staff: Good question, I have never measured it. I opened a post in our forums. A Pelican community member may be able to answer your question.
- Nick at Pelican Parts
gsliz Comments: I cannot get a 10mm triplesquare to fit - this is true of my original alternator and a rebuilt I just purchased - seems too large - is a 10mm triplesquare or does it jus t look like one?

Advice please
January 2, 2014
  Followup from the Pelican Staff: I don't see that size mentioned in the article. What vehicle are you working on? Can you share a photo of the fastener in question? - Nick at Pelican Parts  
993 Comments: great instructions. thx
March 28, 2013
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
ralphedo Comments: That 12 Point Allen Wrench is a 10MM. It is also known as an XZN Triple Square 10 MM. They sell an entire set of these type wrenches on Amazon for about $20 and can be used for many German cars, seat mounts and some Brake calipers. Search for XZN triple square. You should keep the 10MM in the car for emergencies.
December 14, 2012
  Followup from the Pelican Staff: Thanks for the input on this one. We appreciate the help.
- Nick at Pelican Parts
galileo Comments: Hi, do I need to also purchase new shims to replace belts. Or do I use existing shims?

March 9, 2012
  Followup from the Pelican Staff: You can reuse your shims. - Nick at Pelican Parts  
traveller Comments: It would be a good idea to list the size of that 12 point allen key, which I believe is a triple-square.
May 18, 2010
  Followup from the Pelican Staff: Thanks for the feedback. it is a 10mm triple square. - Nick at Pelican Parts  

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