[jaap]

This weekend I had a look under the valve cover. Although no teeth are missing yet, the intake side cam worries me. It looks likes two teeth are damaged. The exhaust side and top guide (difficult to see lower guide) look ok? The chain feel tight in de vertical direction but there is some movement side to side. Would it make sense to replace the chain and guides or is the wear already to much and am I looking at replacing the cams?













how do you post images as thumbnails links?

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[Etnier]

how do you post images as thumbnails links?

You use the "File Attachments" area in the bottom of the posting window.

However, IMHO if you can host your own photos (as you can), it's a lot easier on the reader to view normal-sized images in-context rather than doing all that clicking and navigating.



I view the file attachment / thumbnail option as being mostly useful for images the poster doesn't want to or can't host, or for pictures that are so large they'll "blow out" the window horizontally.

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[BruceWard]

It is surprising that your top pad looks pretty good but your teeth have been wearing. Perhaps the bottom pad is in bad shape.



How many miles are on your 968?



I think you will need to do something about those teeth. If enough teeth were to break off the result would be the same as a timing belt failure.



RSBarn can exchange your camshafts for a refurbished pair and a heavy duty chain for $650 http://www.rsbarn.com/968cam_repairs.html



Parts Works (800) 366-9147 can replace the sprocket on a camshaft for $295.



I think it would be worthwhile to call around and see if anyone can weld new material to those chipped teeth and regrind and balance back to factory specs. This could be a cheaper option. I addition to the two places above I would contact Al Zim http://www.allzim.com/ who does perform similar welding for other Porsche parts.

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[BruceWard]

I also prefer the larger in line images to the thumbnails that have to be opened separately.

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[jaap]

There is 175 kkm (110k mls) on the car. The thing I noticed about the chain is that I can slightly shift individual links side to side. Looking at other peoples pictures it is probably common because I also see some links being offset to one side. Or could this have causes the wear? It also surprises me that the chain rollers? are not closed. They are a rolled piece of metal which leaves a seam where the edges touch. Doesn't this cause extra wear and is the heavy duty chain the same construction. I will have a look around here in the netherlands for some companies that may be able to do cam repairs.

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[Greimann]

I think we all have seen pictures of the camdrive that was much worse. The tips of the teeth are stll very broad and flat, not knife edged. There are a few chips around the outer edge, but I think that is almost normal. Many pictures show this. The clean look of the area shows they have had a steady diet of synthetic oil. If it were me, I don't think I would be rushing out immediately for a new setup. Lots of life left.

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[flash]

in a conversation with pete from rs barn, he reminded me of something i learned a long time ago from motorcycles - one thing NOT to do - don't change the chain without changing the cam sprockets - the new chain will shread the wear patterned teeth on the sprockets in a much shorter time than you would like

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[jaap]

Greimann

Yes, the car has been running on synthetic oil at least for the 65k mls I have it and has seen regular service. I was initially happy with what I saw until I rotated the cams and found these two chipped areas of which I was/am not sure what to think.





Flash,

I am absolutely no expert but what you say also makes sense (or at least I want to believe it). I know that if I have to change the drive chain on my motor bike they always recommend to change the sprockets too.



Jaap

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[flash]

yeah - i have no data or experience with this chain setup to support or dispute the concept, but it has been the case with every other car or bike i've ever had, and i trust pete's opinon, which supports it as well

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[BruceWard]

I guess we will have to wait until more owners have changed their chains and then doubled their mileage to know if the "change both chain and sprockets" theory is correct. I can see it either way.



If you leave it as and it breaks you will have to resurface the head ($500 to $800), replace zero to sixteen valves ($0 to $800) and replace the head gasket ($200) as well as replacing the sprockets, chain and pads. My costs assume you take everything apart and put it back together yourself.



Also if you fix it before it breaks you can preserve the timing which will avoid the need to retime when reassembling.

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[flash]

i don't think anybody is arguing the wisdom of changing the chain, just changing it without simultaneously changing the sprockets - certainly you would not want to leave a questionable chain in there

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[Eric_K]

The teeth don't look that bad to me. There is definite wear. If it was my car I would just change the pads and chain. It is too expensive to change cams everytime you change the chain. I would just monitor the cam more frequently as it has few suspect teeth. You have to lose quite a few teeth before it becomes a BIG problem. When I lost teeth on my intake cam, I just replaced it with a used cam and replaced the chain and pads. Granted, it is not an optimal solution but the economics work better.



BTW, I prefer the thumbnails with the images loaded to the forum. When people post images they host themselves eventually that image is moved or removed and then when you do a forum search later all the relevant images are gone. If you load the image with the post then they are together forever <img src="/forum/images/smilies/968/smile.gif" class="smilie" alt="" /> .



Eric

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[jaap]

Thanks,



I appreciate everybody's input on this so I can decide what to do. Unfortunately I think the options for repairing cams are limited in the netherlands so when I want to replace them I probably have to buy new ones. (or try to get a second hand set). Is there a diy description for replacing the chain/pads or is this documented in the workshop manual? Is there a way to determine if the chain is actually stretched without removing?



Jaap

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[Eric_K]

Here is a link to some one who documented it:

http://freespace.virgin.net/mrmike.hammond/project3.htm



If the chain isn't new then consider it stretched (to some degree).



Eric

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[flash]

i guess it's somewhat a roll of the dice - as eric says, plan to keep an eye on it more frequently, and you should stay out of trouble

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[BruceWard]

Did you get a mirror and look at the bottom pad? The bottom pad can be bad while the top one is ok.

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[ds968]

[quote name='BruceWard' date='Nov 2 2005, 03:25 PM']Did you get a mirror and look at the bottom pad? 

[right][post="12032"]<{POST_SNAPBACK}>[/post][/right][/quote]



Crap ! Why didn't I think of this when I did the visual on mine ?



Bruce, dang-it , you should have posted this a few months ago !! <img src="/forum/images/smilies/968/tongue.gif" class="smilie" alt="" />



But good to know, thanks - I'll remember that for the next inspection when I reach

100k mi.

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[jaap]

No I did not use a mirror, which would have been a good idea, so unfortunately I don't know the condition of the lower pad <img src="/forum/images/smilies/968/sad.gif" class="smilie" alt="" /> . Now that I know the inspection is a simple procedure I will do it more frequently (or maybe just do it right now again).

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