[Darth Vadar]

Any info from the 968 Group at large is appreciated on this one!



How many of you have had to change out your camshafts due to the Variocam Drive Chain wearing the Cam Gears down to a nub? And if so, approximately how many miles on the car?



How many have had their Variocam Chain and Tensioner Pads replaced? And at approx what mileage?



Has anyone actually changed out the Variocam Tensioner itself? Was this before or after the Cams failed and you rebuilt your engine!?!?



I have purchased a new Cam Chain and Pads, and was planning on replacing these items during a routine Belt and Roller change, but my mechanic friend has made me VERY nervous by stating that what often happens is that the "cheese head" bolts for the Cam Saddles will shear off when you are trying to loosen them, causing all sorts of future havoc, not the least of which is replacing the cylinder head if you can' t remove the old bolt stubs... NOT something I really wanted to face!!!



Does anyone have a suggestion as to how to "assist" the removal of these bolts? Tap on them to unseat them? Heat each one with a propane torch? Impact Driver to loosen them? Air Impact Wrench? I am willing to try anything that has a proven history!



Then there is the issue of Camshaft Sprocket Wear... Any idea what a pair of new Cams is running these days??? I hesitate to ask Porsche... my heart probably can't stand the shock... and I doubt that there are very many pairs of nice used ones floating around out there! If you have a set, drop me a note and we can talk!



Ah, the joys of Porsche ownership! In the old days, it was Cam Chain Tensioner failure in my 911L... now, 40 years later, you would have thunk they would have gotten beyond that issue!!! Guess not!

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[au968]

Hi.



Are you a member of the UK Forums? There's a similar thread there:



http://www.porsche968uk.co.uk/phpbb/view...php?t=4080



If not, it basically goes like this...



* The Chain stretches with use, causing wear on the cam sprocket.



* Eventually, one or more teeth fail. $$$



The recommendation is to replace chains at 45k miles. Porsche has modified the sprockets on the replacement cams to be more resistant to wear. (pointier teeth)



There is no mention of cheese-head bolts in the cam saddles, but I will post your question over there and see what the response is <img src="/forum/images/smilies/968/smile.gif" class="smilie" alt="" />



No idea what the parts cost, but bet on it not being cheap...



Michael

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[mefforddk]

[quote name='Darth Vadar' post='28280' date='Nov 24 2006, 05:05 PM']Any info from the 968 Group at large is appreciated on this one!



How many of you have had to change out your camshafts due to the Variocam Drive Chain wearing the Cam Gears down to a nub? And if so, approximately how many miles on the car?



How many have had their Variocam Chain and Tensioner Pads replaced? And at approx what mileage?



Has anyone actually changed out the Variocam Tensioner itself? Was this before or after the Cams failed and you rebuilt your engine!?!?



I have purchased a new Cam Chain and Pads, and was planning on replacing these items during a routine Belt and Roller change, but my mechanic friend has made me VERY nervous by stating that what often happens is that the "cheese head" bolts for the Cam Saddles will shear off when you are trying to loosen them, causing all sorts of future havoc, not the least of which is replacing the cylinder head if you can' t remove the old bolt stubs... NOT something I really wanted to face!!!



Does anyone have a suggestion as to how to "assist" the removal of these bolts? Tap on them to unseat them? Heat each one with a propane torch? Impact Driver to loosen them? Air Impact Wrench? I am willing to try anything that has a proven history!



Then there is the issue of Camshaft Sprocket Wear... Any idea what a pair of new Cams is running these days??? I hesitate to ask Porsche... my heart probably can't stand the shock... and I doubt that there are very many pairs of nice used ones floating around out there! If you have a set, drop me a note and we can talk!



Ah, the joys of Porsche ownership! In the old days, it was Cam Chain Tensioner failure in my 911L... now, 40 years later, you would have thunk they would have gotten beyond that issue!!! Guess not![/quote]



I just removed my cams to have my head rebuilt. I had no issues with the 12pt serrated cam bolts. Use the correct tool (short shank version). Tap each one with a with a hammer to break the bolt lose. Also clean out the serrated area before inserting the tool to insure a good ft. I removed mine with stripping one out, but it still came out. The inside was a little "gunked" up and the tool didn't seat well.



I replaced my pads and not the chain. I have 114K miles. I just rebuilt the head and replaced a lot of front timing parts. A quote from Sunset Porsche concerning chains



"We seem to sell them as a maintenance

item when people are working in that area. Strange thing is in an older

Excellence tech article I remember reading it said the chain is

sometimes replaced too often. That's a vague statement but if you are

interested I'd check into other people's experience in this issue in

online forums perhaps. The article mentioned the pads are more likely to

wear out than to have the chain stretch. A worn out pad or two can make

for the feeling the chain is loose is where they were going with that

magazine article from what I remember. "

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[Darth Vadar]

Thanks for the pointer to the UK site. I just signed up.



Yes, i have seen the photos of the cam sprockets worn to a nub,and I don't EVEN want to go there!



BUT, If I have to replace the cams, what am i looking at in parts cost alone???

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[au968]

Hmm...



I think I'd replace the chain.



The theory is that all chains stretch with use, and yours and mine have had plenty of use.



Once the chain stretches, it fails to make even contact on all the teeth on the sprocket, (it's pulling on the first tooth, the others are having a bit of a holiday) and then the wear starts.



The tensioner working properly does not repair the stretched chain or prevent it's uneven pressure on the sprocket teeth.



The unknown is, if the sprockets have started to wear, will replacing the chain arrest or accelerate the decay?



Michael

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[Darth Vadar]

[quote name='mefforddk' post='28290' date='Nov 24 2006, 11:06 PM']I just removed my cams to have my head rebuilt. I had no issues with the 12pt serrated cam bolts. Use the correct tool (short shank version). Tap each one with a with a hammer to break the bolt lose. Also clean out the serrated area before inserting the tool to insure a good ft. I removed mine with stripping one out, but it still came out. The inside was a little "gunked" up and the tool didn't seat well.



I replaced my pads and not the chain. I have 114K miles. I just rebuilt the head and replaced a lot of front timing parts. A quote from Sunset Porsche concerning chains



"We seem to sell them as a maintenance

item when people are working in that area. Strange thing is in an older

Excellence tech article I remember reading it said the chain is

sometimes replaced too often. That's a vague statement but if you are

interested I'd check into other people's experience in this issue in

online forums perhaps. The article mentioned the pads are more likely to

wear out than to have the chain stretch. A worn out pad or two can make

for the feeling the chain is loose is where they were going with that

magazine article from what I remember. "[/quote]





Well, at least that is encouraging... so for a car with 50K on it, the Cam Sprockets shouldn't be worn out yet, and if I do the new chain and pads, i s/b good for another 50K... I like the sound of that! Of course, I haven't pulled the Cam Cover yet to see "What we have under the covers!!!" Oh, boy...how exciting!

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[doster]

[quote name='Darth Vadar' post='28293' date='Nov 24 2006, 08:36 PM']Well, at least that is encouraging... so for a car with 50K on it, the Cam Sprockets shouldn't be worn out yet, and if I do the new chain and pads, i s/b good for another 50K... I like the sound of that! Of course, I haven't pulled the Cam Cover yet to see "What we have under the covers!!!" Oh, boy...how exciting![/quote]



Ya i'm about to do the same and have been ordering the parts needed,allready have the seals for the cover

new rollers and tentioners,pads and chain.. but I'm not sure what alse i should replace,fallowers,bearings,

cam seals etc? Does anyone have a good list of parts that should be replaced while in there.



Good luck Darth!!

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[Darth Vadar]

I went for: Front Oil Seal Kit - $99.00, Cam Chain - $30.00, 2 Variocam pads - $72.00 (for both), Cam Cover Gasket and Spark Plug Hole O Rings...(lost the invoice on the last bits). Figure you may strip a bolt or two, and need those for the Cam Saddles, but I didn't see anyone recommend replacing all of them with new hardware, so I am going to trust them. And, my Variocam Device seems to be working just fine, so I am assuming it wil continue to do so!



Best of luck and let us know how you make out... I will do the same!

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[TonyBray]

[quote name='Darth Vadar' post='28324' date='Nov 25 2006, 08:47 PM']I went for: Front Oil Seal Kit - $99.00, Cam Chain - $30.00, 2 Variocam pads - $72.00 (for both), Cam Cover Gasket and Spark Plug Hole O Rings...(lost the invoice on the last bits). Figure you may strip a bolt or two, and need those for the Cam Saddles, but I didn't see anyone recommend replacing all of them with new hardware, so I am going to trust them. And, my Variocam Device seems to be working just fine, so I am assuming it wil continue to do so!



Best of luck and let us know how you make out... I will do the same![/quote]



I'm planning the same for my car just after the first of the year. You can get rebuilt cams from RSBarn for $700 exchange. They have new sprockets welded on. I posted a similar question recently and was told that you need a special tool to compress the variocam unit. I'm interested in any info on doing this myself so whoever has done it, speak up. Maybe do a tech article as well?



--Tony

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[Darth Vadar]

After searching thru all of the Topics here, I found all of the info I needed, down to the suggested sources for the Triple Square Sockets to pull the Cheeseheads from the Head (toomuch time on my heands!)



Now to tackle what my mechanic really didn't want to do!



I will keep you posted!

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[doster]

[quote name='Darth Vadar' post='28324' date='Nov 25 2006, 06:47 PM']I went for: Front Oil Seal Kit - $99.00, Cam Chain - $30.00, 2 Variocam pads - $72.00 (for both), Cam Cover Gasket and Spark Plug Hole O Rings...(lost the invoice on the last bits). Figure you may strip a bolt or two, and need those for the Cam Saddles, but I didn't see anyone recommend replacing all of them with new hardware, so I am going to trust them. And, my Variocam Device seems to be working just fine, so I am assuming it wil continue to do so!



Best of luck and let us know how you make out... I will do the same![/quote]



Are you planning on a new water pump when your in there i've heard

its a good idea. (but then again if its not broke don't fix it!!!)

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[Darth Vadar]

Mechanic says the Water Pump looked fine and appeared to have been replaced at the last belt change (30K miles or thereabouts), so we are going to leave that one alone for the time being!



I'm sure I will come up with something else tho... this old girl is definitely higher maintenance than my last girlfriend! I'm going to look at a 968 engine that was pulled from an 80K mile car... if the price is right and the cams look good, I may just mothball it and use it as needed for future parts picking! Like starting my own junkyard!



I'm thinking I might pull the head and send it out to RSBarn for the fancy redo...then use it as a display piece under my glass coffee table until I manage to destroy the current one! Wait 'til the wife hears of this idea!!! WhooEeee! The Holidays may get a LOT more interesting!

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[gbarrier]

Our 968 had 100K miles on it when we bought it so I figured we had issues and was right. Every fourth tooth was intac. Compressing the tensioner is easy. Just go slow in the vise. Use 3/32 welding rod or clothes hangar to make retaining tool. Still need to be careful while pulling the cams down into place without the factory spanner that noone seems to have. Searched web and found new cams for about $600 each and chain for alomost nothing. Later I found out about the RS Barn rebuilt ones. Would have probably done that. I too belive that the chain stretch causes tooth wear. The worn pads are somewhat incidental but certanly should be replaced while you're in there. I plan to change the chain again in 50K.

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[ether_joe]

the 'things every 968 owner must know' thread has a PDF of a variocam inspection and maintenance procedure.



Really good article.



also you might want to order replacement bolts for the cheeseheads . . . why not get allen bolts. . . what's the term for the high-grade bolt that's needed? Grade 11 or something? The black ones.

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