[ds968]

I'm close to 90k miles and IIRC, at the prescribed variocam inspection and service timeframe. However, about 15-20k miles back while changing the cam cover gasket the variocam looked as if it was brand new. Not the slightest VISIBLE wear on any of the teeth, the upper pad had no grooves on it at all, the guides(?) were just as brand new looking as everything else, chain was perfectly tensioned, so on and so forth.. and although I understand there could have been some wear on the bottom pad or parts which were not visible from the top, given the condition of everything else, that seemed highly improbable.



Fast forward to present day: I told my mechanic that it's time for the variocam service, to which he replied: " - Why, have you heard any noise ? " . I advised him, no but it's just preventive maintenance, to which he, again, responded that it's not really needed with the variocam until you hear it, but if I want to spend the money, he'll be happy to oblige.. He supported his theory by suggesting that unlike the possibility of a timing belt breaking suddenly, there is plenty of advance warning with variocam components wearing out, losing a tooth ot two, etc. because the chain will become looser and looser and you will hear it, but since it has no room to jump off anywhere and screw up the timing / bend your valves, there is plenty of time to fix it - at the time when it's audible, so there's little point in doing anything before then..



So, in spite of the fact that he has worked on porsches, old and new, for over 30 years, I am not fully at ease with this theory, though I vaguely recall on that old thread a few agreed with what my mechanic asserts ( also the shape of my variocam as mentioned above, albeit more than a year ago, gives me some comfort level..) .



So what do you think ?

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[SILVY968]

Before I bought my 968 the timing chain went without warning on the freeway. The resultant damage was severe. I have the service records from the previous owner, to prove it. I have found that with these cars following the maintenance schedule is expensive but not in comparison to the costs if you do not.

Almost everything that has failed in my 968 has happened without an " early warning" noise. When thing go, they usually just go. When it comes to engine maintenance I stick to the schedule. If my PM does an inspection and everything looks OK there is a strong tendency to trust his opinion and save the cash; but Porsche knows when things are beyond their normal service life and prone to failure. Ask your PM if he will repair any collateral damage to your engine if the chain or any of the other related components let go, if he says no you have your answer.

Other than the inconvenience factor, the cost to repair what has broken and the other items that it took out on the way, if greater than the preventative costs.

Good Luck,

Brian

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[S_Cal968]

Dan,

Between the 2 forums the responses are all over the map. I hope we haven't increased the fog per se...

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[orphanowner]

Find another mechanic. On my 50K mile coupe the upper pad looked great and the chain looked perfectly tensioned (this alone is a fallacy and worth booting the mechanic that said that!!) but the lower pad looked very worn with dual grooves cut into it from the chain. Not ready to fail, but how close do you want to come to what is a major repair in failure mode?



You can't "wait" until you hear the "noise" to make the repair. These aren't 911 cam tensioners...



I replaced both pads and the chain.

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[H2Ojazz]

Sorry, no idea. Totally distracted by moving picture.



<img src="/forum/images/smilies/968/blink.gif" class="smilie" alt="" />

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[rustech]

Dan, be happy that they see no wear on the non-wear items. But when is the "sign" to change it then, when the teeth start to wear thin? When you lose a tooth? When the bottom pad fragments? With that mileage, I wouldn't skip it on the next belt change, I did it at 95k and feel relieved I did, no wear also.

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[Guest]

As a reference point, mine looked fine at 150K+ miles.

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[whakiewes]

Does anyone have the part numbers for the typical variocam service. I would like to do my whole upper end service, and for some reason I can't find what would appear to be what I need in PET.



Thanks,



Wes

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[ds968]

[quote name='H2Ojazz' date='Sep 24 2006, 06:15 PM']Sorry, no idea. Totally distracted by moving picture.

<img src="/forum/images/smilies/968/blink.gif" class="smilie" alt="" />

[right][post="26381"]<{POST_SNAPBACK}>[/post][/right][/quote]





<img src="/forum/images/smilies/968/rolleyes.gif" class="smilie" alt="" /> <img src="/forum/images/smilies/968/laugh.gif" class="smilie" alt="" /> me too. I love that clip.



It's really not the cost of the service that holds me back, it's just me... I'll go to the doctor when a part finally falls off <img src="/forum/images/smilies/968/ohmy.gif" class="smilie" alt="" /> <img src="/forum/images/smilies/968/tongue.gif" class="smilie" alt="" /> , not when conventional wisdom tells me I should have a check up.. <img src="/forum/images/smilies/968/blink.gif" class="smilie" alt="" /> Next T-belt job is around 120k miles, I'll definitely have the cam chain and pads replaced at that time, but was just wondering if I should do it before..

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[bob blackwell]

Dan, from your description I would probably wait until the next scheduled belt service and have it done too. On the other hand, when I had my variocam mechansim inspected at about 86K there were teeth missing from the exhaust cam sprocket. No noise was evident, and the engine was running fine. Good luck, Bob Blackwell.

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[orphanowner]

This what the chain guides looked like from my 1994 coupe with 51,000 miles, always synthetic oil, no noise, no running issues. The chain guides are shown in the installation position, upper is nice, lower is pitted. I couldn't see the condition of the lower until I removed the Variocam device.



I lined up the old chain with the new one and the pitch looked identical. No cam wear either.

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[Harvey]

[quote name='orphanowner' date='Sep 26 2006, 07:21 AM']This what the chain guides looked like from my 1994 coupe with 51,000 miles, always synthetic oil, no noise, no running issues. The chain guides are shown in the installation position, upper is nice, lower is pitted. I couldn't see the condition of the lower until I removed the Variocam device.



I lined up the old chain with the new one and the pitch looked identical. No cam wear either.





[right][post="26405"]<{POST_SNAPBACK}>[/post][/right][/quote]



Orphanowner,



Which guide is the upper and which is the lower?



Harvey

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[Dave]

My P-car mechanic also subscribes to the "it'll make noise" on the Variocam wear issue. That said, we both agreed it was smart to inspect and replace pads/chain at 135k+ miles, especially given it's use.



It was one of those things that was going to keep me up at night wondering.



BTW - it takes some special tool to check the operation of the Variocam, IIRC. My mechanic invested in the tool without hesitation.

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[Eric_K]

Regular inspection is the best bet. If teeth are not missing and the upper pad looks good then chances are you are fine. But there are no guarantees, as shown by ophan's pick of the lower pad. The cams can lose a few teeth and the engine still run fine (even at high rpm) and not make noise - ask me how I know. If you want peace of mind, and a lighter wallet, refresh everything.

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[TonyBray]

So, the "service" would be pads and new chain assuming the cam sprockets are fine? What's the time estimate for doing it yourself and are there any special tools required that a home mechanic might not have? Are the pads and chain available seperately? I know when I had my 944S, the tensioner pads weren't available seperately, only came with a new full tensioner.



--Tony

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[orphanowner]

[quote name='TonyBray' date='Sep 27 2006, 05:35 AM']So, the "service" would be pads and new chain assuming the cam sprockets are fine?  What's the time estimate for doing it yourself and are there any special tools required that a home mechanic might not have?  Are the pads and chain available seperately?  I know when I had my 944S, the tensioner pads weren't available seperately, only came with a new full tensioner.



--Tony

[right][post="26457"]<{POST_SNAPBACK}>[/post][/right][/quote]



The idea here is to prevent cam sprocket wear due to a worn cam chain. Think of a motorcycle chain and sprockets, once the chain wears and starts to stretch, the chain will no longer properly line up with the sprocket teeth because the chain pitch is now slightly off from being worn. This pitch change will start to wear the cam sprocket teeth, eventually getting to the point of losing teeth. The whole process left to its own will destroy the cam sprockets. I look at doing pads and a chain as cheap P.M. for this system. Unlike the motorcycle example, the cam sprockets are not replaceable, you have to buy new cams or have the sprockets repaired. Seems like $125 in parts is a cheap price to pay to keep this system in top condition. Of course there is a labor component for anyone not doing this DIY that will add in about $250 to the P.M, but still way cheaper than the alternative failure mode



About the repair:



There are a few special tools that Porsche says you need to have to do the job properly. The job can be done without the camshaft holding fixture by carefully drawing the cams into the bearing saddles with the cam bearing caps. This is a very delicate operation and not for the faint hearted. There is potential to bend valves, strip cam bearing cap threads, damage cam bearings (read replace head) or even snap the cam caps in two. However, I have done this service many times without the tool by going slowly and evenly with the intake cam first and then the exhaust cam, all the while making sure the Vario is in compression and evenly spaced between the cams. The pistons should be about 90 degrees past TDC so you don't bend valves (I think the book points this out too).



There are also pair of pad clamps that are used to hold the Vario device clamped in the compressed state, which is the only way you can install it. This can be rigged with coat hangers but it is a very delicate operation as well. I use a vice with rubber pads directly on the chain pads to compress the Vario and then insert the holding clamps. You have to try to have the unit fully compressed, or you will have a frustrating time with the whole process of installing the cams, chain and Vario hydraulics, which have to be installed as one unit.



There are two chains available, a standard and "racing" version, these are both somewhat cheap at $15 and $25. The pads are available form Porsche but the part number is somewhat obscure and you have to find a dealer that knows about this. The part number for the pads, upper and lower are the same, is 944 105 509 00 You can also buy the pads for $90 a pair from Paragon who gets them from Zims, who seems to be the exclusive importer of these parts.



Good luck!

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[gbarrier]

Had ugly tooth wear at 100K when I purchased the car. Only slight noise going up or down past 2K and could only hear it with the hood up and listening carefully. With 1 out of every 4 or 5 teeth still intact don't think it would have held together much longer.



Can't help but belive that if the chain is changed at regular interval (and I suspose pads too while you're in there) this could be prevented. A chain is a whole lot cheaper than cams.

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[ds968]

bringing up this old topic because I was looking at the maintenance schedule pages and found no reference to variocam inspection interval. did I overlook a page or a segment in that booklet, or did Porsche fail to include something that critical in the prescribed service ? I think the 90k or 95k miles suggestion came from a couple of local 968 owners or may be a mechanic I spoke with some time ago, but I can't believe it's not in the manual.. or is it ?

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[flash]

your'e not nuts or blind - i can't find it either



off topic - how many people are lubing their hinges every 15k?

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[Cloud9...68]

The variation in the wear of these things is incredible. Out of paranoia (and lack of any record that it had been done), I replaced my variocam pads and chain right after I got the car, at about 85K. When I saw them, they were utterly indistinguishable from brand new - a total waste of money in my case. But there are plenty of examples of components that are totally trashed at less than 50K, so there's no rhyme or reason here.



Before you shell out the $600 or so to replace your pads and chain, there is a great description of how to inspect your variocam components by Derek Holliday and Ugo Manfredi. I've tried attaching it here. If it didn't take, hopefully you can still do a search on 968.net for it.



I foolishly didn't do the described inspection procedure, instead taking the attitude that given the mileage on the car, I might as well just do it. In other words, I made a decision without data (bad engineer!). The inspection procedure sounds very simple - I would recommend following it, and then deciding whether to replace the parts now, or waiting till the next belt service. This is a matter of some dispute, but the older I get, the more I find wisdom in the old adage, "If it ain't broke, don't fix it."

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