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All done!
#1

After about two weeks of chipping away a little each every night, I finally finished the install of

new balance and timing belts, and new oil seals for the balance shafts and crank shaft.



Those seals must have been the originals, and were extremely difficult to get out. Bent two

picks working on pulling them out. Does anyone use a special tool for removing these seals?



My neighbor, Chris, who is nuts about the VW Corrado (he has two of them), helped me to get the timing and balance sprocket marks lined up correctly. Thanks Chris!



The old timing belt was a half a tooth late (to the left of the mark) on the cam sprocket. Maybe it

stretched a little bit over the past 4 years and 25K miles?



The new belt is precisely on the mark for TDC. I was glad to see that.



The balance belt is a bit too tight, and I will have to take a bit off the tensioner to stop the whining.



Now I am happy again driving the only car for me.
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#2

Great job scott I can feel your pain about the hour or two a night, Its tough!! Don't have advice on an easier

way there allways a pain <img src="/forum/images/smilies/968/huh.gif" class="smilie" alt="" />
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#3

Awesome job, Scott! I'm looking forward to seeing Claudia in action again...you gotta come and check out the new car!



Steve
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#4

Thanks Doster! Thanks Steve!



Glad it's done. Next project will be to replace power steering hoses and reseal the

oil pressure sensor, which I believe are all leaking.



Own a 15 year old Porsche, and you always have plenty to do!
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#5

congratulations Scott. . . I am about two months behind you on the same job. woohoo!
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#6

Out of curiosity, what did you use to set the tension on the timing belt?
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#7

There's an oil filled tensioner for the timing belt, it's the balance shaft belt that's tensioned manually.



Steve
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#8

Good job, enjoy the fruits of your labor and drive the car a while before adjusting the tension - the whine usually goes away as the belt settles in and stretches a bit. Good luck, Bob Blackwell.
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#9

Thanks for the advice and cheers.



As Steve Z. mentioned, the timing belt tensioner is hydraulic, and adjusts the tension automatically.

(I should get the tensioning tool and check the tension to verify that the hydraulic tensioner is working

properly. I should, I should, I should.....)



When you remove the tensioner to replace the belts, seals, and rollers/tensioners, you compress

the tensioner in a vice, in stages. Go a little bit, wait, then go a bit, wait, etc.

It takes more pressure than you might think to get it retracted. I would like to see a cutaway diagram

of how the tensioner works. Anyone have that?



And be sure to put a large washer (I used an old bearing that fit perfectly)

to go over the end of the tensioner so that there is no pressure on the protrusion in the center/rear of

the tensioner.



You need a nail or pin that is fairly strong yet thin enough to fit through the holes and lock the tensioner in

the retracted position. Porsche makes this special tool, but I don't have it. Who does? Make sure it is inserted so that it can be pulled out away from the motor after

the tensioner is wigged back into place. (I am actually proud of myself for anticipating this and

not screwing it up <img src="/forum/images/smilies/968/tongue.gif" class="smilie" alt="" /> )



I tensioned the balance belt the same way I did it the last time - by feel and sound. I just get it to

where it will whine, then back it off just a bit. Not scientific, but seemingly effective. The Arnnworx

27mm wrench is perfect for this job. Perfect. (Arnnworx.com)



When I was done, I only had a few nuts and bolts left over, so I figured that was good enough! <img src="/forum/images/smilies/968/ohmy.gif" class="smilie" alt="" />
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#10

[quote name='Scott Collins' post='42458' date='Oct 17 2007, 01:49 AM']Porsche makes this special tool, but I don't have it. Who does? <snip> The Arnnworx

27mm wrench is perfect for this job. Perfect. (Arnnworx.com)[/quote]



If you have it down well enough setting the tension manually like you say, then good for you!



It was my understanding that the "automatic tensioner" is only meant to help replace the belt, not for setting the tension. Coincidentally, Arnnworx also makes a proper tensioning tool called the P920X.
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#11

"It was my understanding that the "automatic tensioner" is only meant to help replace the belt, not for setting the tension."



No offense but I'm wondering how you would adjust the "automatic tensioner" to set the tension according to a tool? Seems to me that once you release the tensioner, you can only check that "it" is working properly and would have to replace it completely if it was out of specification or am I missing something?



--Tony
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#12

[quote name='TonyBray' post='42492' date='Oct 17 2007, 09:07 AM']"It was my understanding that the "automatic tensioner" is only meant to help replace the belt, not for setting the tension."



No offense but I'm wondering how you would adjust the "automatic tensioner" to set the tension according to a tool? Seems to me that once you release the tensioner, you can only check that "it" is working properly and would have to replace it completely if it was out of specification or am I missing something?



--Tony[/quote]



Your not missing anything, with the 968 engine you do not set the tension of the timing belt with the 920x tool, the hydraulic tensioner takes care of that. On the S2 motor and all other 944 motors you had to do that because there was no hydraulic tensioner. The balance shaft belt does technically require the 920x tool, but you can do that one by feel and sound. Check the shop manual for the 968 engine and you will find no reference to the 920x tool or any type of tension check for installing the timing belt.
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Current:
2016 Cayman S
Former:
94 968 Cab 6 Spd. Black/Cashmere D1R SC
86.5 928 Garnet Red Metallic
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#13

[quote name='banditsc' post='42496' date='Oct 17 2007, 06:30 AM']Your not missing anything, with the 968 engine you do not set the tension of the timing belt with the 920x tool, the hydraulic tensioner takes care of that. On the S2 motor and all other 944 motors you had to do that because there was no hydraulic tensioner. The balance shaft belt does technically require the 920x tool, but you can do that one by feel and sound. Check the shop manual for the 968 engine and you will find no reference to the 920x tool or any type of tension check for installing the timing belt.[/quote]



Banditsc et All-



Could not have said it better.



Since we are always talking about two different belts, timing and balance, there is the possibility for some confusion.



It's actually a relief that the 968 3.0L motor uses a hydraulic tensioner that automatically adjusts the

tension on the belt when it is installed. My plan is to get the Arnnworx tool so that I can measure the

tension on the timing belt, just to verify that the hydraulic tensioner is doing its job properly. Then if

tension is not correct, I can replace the faulty tensioner before it causes the kind of damage that can really

ruin a perfectly nice day, if you know what I mean...



One of the many things that I think could have be done better on the 924/944/968 cars. For instance, the tensioner could come equipped with a sensor that would provide a tension value and readout on the dash, and alert the driver in the event of a problem. The alert symbol could be a huge " <img src="/forum/images/smilies/968/sad.gif" class="smilie" alt="" /> " that would blink really quickly. And/or the tensioner could have a lever or other design that would allow easy retraction of the shaft, and removal of the timing belt without removal of the tensioner itself.



The Porsche 968 workshop manual mentions the Porsche tool that is used to hold the hydraulic timing belt tensioner in the retracted position. I used a nail, then pulled it out with pliers after the new timing belt and tensioner were both in place back on the engine. A friend refers to this kind of approach as "Caveman style", so I guess that makes me a knuckle dragger. But it worked!



Anyhow, I really enjoy the dialogue on this forum. Keep it coming!
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#14

928's do have a "You're screwed" light to show when there's a problem with the timing belt.



I don't know that I'd want that....I might get under the car with it rolling if it came on!! <img src="/forum/images/smilies/968/wink.gif" class="smilie" alt="" />

Steve
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#15

Add me to the "DIY belt change" club - finished my this week. Like Scott, it took me the course of about a week and a half, chipping awya at it bit by bit, to complete the job. In addition to the belts and rollers, I replaced the front balance shaft seals, water pump, thermostat, timing belt tensioner, and I even replaced the tensioner pivot pin. To you guys who say you can do this job in 2-3 hours, all I can say is, "I am not worthy... I am not worthy...!" 2-3 hours!!!??? Just making sure I'm at TDC, jacking up the car, removing the starter, and installing the flywheel lock takes me a good 20 minutes. Sheesh, I couldn't turn all the nuts and bolts needed for this job in 2-3 hours of they were all threaded through a piece of plywood lain flat across a pair of sawhorses. But I digress a little...



Overall, in hindsight, the job isn't too bad, and if I had to do it over, I could probably do in a third the 12+ hours it took me, now that I know what I'm doing. My observations:



The TDC thing: My distributor has a window on top, through which I can see the TDC marks. There's nothing on my car, however, visible either through the tiny window on top of the bell housing, or on the flywheel through the starter opening. So I spent (wasted) quite a bit of time stressing over whether I was really at TDC. I think the easiest way to tell is to simply line up the marks between the cam gear and the housing, and noting the position of the rotor. It should look like figure 792-15 on page 15-4 in the manual. If I had seen that figure before I started, I would have taken care of TDC in about a minute.



Special tools: The only thing I needed to buy was the flywheel lock. My neighbor has a pair of pliers bent at 90 degrees, which did the job of holding the balance shaft sprockets while I was lossening/tightening their bolts. No need for the $50+ pin wrench. I would, however, recommend shelling out the $27 or so for the 27 mm flat wrench available at Paragon and other places. This would have made the setting of the balance shaft tension more convenient.



Balance shaft seals: Mine weren't too hard to get out, though for some reason the top one was tighter than the bottom. I ended up drilling through the top one, threading a drywall screw, and yanking it out with a pair of large pliers. The bottom one came out with a good yank using a pick. Very important, though: I found out the hard way that the OD of the upper balance shaft seal is 47 mm, and the bottom one is 48 mm. The diameters are stamped into the seals. I didn't notice this, and ruined a seal trying to force a 48 mm seal into the upper shaft housing. Doh!



Water pump: Let the slings and arrows fly, but I refuse to spend two track days worth of money on a new water pump, given that the thing has, oh, like ONE moving part. I bought a remanufactured one from Paragon for just over a hundred bucks. No leaks so far, but I'll keep everybody updated if it springs one. But I did notice something. The original pump has a pair of guide pins that look like roll pins inserted into two of the bolt holes. I tapped these out of my old pump, and (very carefully, making sure I had the pump securely supported on the bottom), tapped them into the same bolt holes of the new (remanufactured) pump. I wonder if this isn't part of the reason several people have had bad experiences with remanufactured pumps. These guide pins are there for a reason, so maybe without them, the pump will "wander" a bit, eventually springing a leak.



Balance shaft belt tensioning: I wish I had found the thread which included two methods for tensioning the belt (the 90 degree twist method, and the RS Barn place-finger-at-4-oclock-on-water-pump-idler-pulley-and-deflect-the-belt-to-this-point method) before I had tensioned my belt, so my neighbor and I ended up doing it by feel. But I think we pretty much nailed it, because the belts whine just a bit for the first 15 seconds or so after start-up, and then quiets down. The last time I did my balance shaft belt, I must have set it too tight, because it took a lot longer for the whine to go away.



I did run into one problem. One of the threads for the water pump bolts stripped as I was installing the pump. I replaced the bolt with one about 1/4" longer, and this holds a little tighter, but I can't achieve the specified 10 nm. I'm at about 7 nm. But so far, there's no sign of a leak around this bolt, which thankfully is the topmost bolt on the pump, and is therfore very accessible. I will continue to watch it very closely, and imagine that at some point, I will have to re-tap this thread. I'll be asking for advice when it comes time to do this, because, oddly, in all my years of working on cars, I've never stripped a thread before, or broken off a bolt. So I'm a little nervous about doing my first tap job on a nearly priceless aluminum engine block. What do you guys think? Do you think it's safe to leave this for now, since it isn't leaking, and fix it at the first sign of trouble? Please nobody tell me I need to remove the water pump to repair this thread, not only because of the time involved, but I'm concerned that if this thread stripped, who knows how many of the others are just a turn away from stripping as well.



Anyway, thanks to everyone, especially Scott, for all the advice they gave me throughout this job. I hope my experience helps somebody else.
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#16

Boy, brings back fond memories. My first one (2003) also took several days, which only make sense when you're checking and double-checking everything as you go.



A few comments: First, the nail to hold the tensioner works fine. Second, an easy way to confirm TDC is to take out the #1 plug, and drop a pencil down until it rests on the top of the piston. As you rotate the crank you'll see when the pencil reaches the highest level and that is TDC. Third, the precision of the balance belt setting is way over done, in my opinion. Mine was too tight, whined a lot and just needed to be loosened some once it stretched itself out. Fourth, something I never saw mentioned anywhere was how to place the belt on to the cam when it's off by a half tooth. I turned my cam pulley CCW a half, thinking that would tighten the run between the crank and the cam. I think now I've seen people say to move the cam slightly CW. Oh well, it runs great the other way. Fifth, it's fun in a perverse way to put all that monster torque on the crankshaft bolt. I didn't know till later that tightness of the crank pulley is what ensures the oil pump turns. So not tightening it all the way could be disastrous later on if your oil pump quits turning.



Finally, just to show the importance of the afore-mentioned checking and double-checking, in my tool chest I now have a souvenir from that job - the woodruff key from the lower balance belt pulley. I finally had to take the car to my shop when I couldn't get the belt to quiet down, and that's what they found, the woodruff key was missing and the pulley was spinning completely out of synch with the balance shaft.
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#17

hydraulic Automatic tensioners are a great bonus...but you have to intitially set the belt to the proper tension before releasing the tensioner...otherwise the hydraulic tensioner may extend too far and not be effective as the belt wears and stretches(sooner than you think in mileage terms)



I would consider a recheck of the tensioner extension to make sure it is within specs after a few thousand miles if set by hand.
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