I'm on my second month of owning this 94 Coupe (93K Mi) and decided I better take a look under the valve cover before my luck runs out. Everything looked pretty good, but i did find one tiny chip in the upper variocam pad. The chain looks good and the teeth on the cam look decent. I do see the beginning of some wear (more like abrasion) due to chain stretch. The train tracks from the chain are a little shy of 1mm. I think I will pull the trigger on changing the pads soon. The article on this site for inspecting the variocam was <i><b>very</b></i> helpful. I now see the potential for the cam pad to break and cause severe damage.
I also found oil in two spark plug holes, but I attribute that to the spark plugs being very loose. I cleaned it up before I took pics. When I say very loose, I mean one of them was finger loose. I verified the seals were good. There was no thread damage from what I can tell. I finished each of them with a torque wrench.
The cam lobes looked good to me, but I don't have a calibrated eye for wear on these cams.
I'm curious if you guys see anything else of concern.
Oil around the plugs is more than likely the cam cover gasket.
Thanks Dood! I'll double check it after a few miles. I'm putting together my pad/chain parts list now and plan to add new seals to it anyway.
The rubber rings around the spark plug holes are what let in the oil in.
I am changing the pad on my car this winter as they have about the same amount of wear < 1 mm; they are deceivingly brown so I thought it might be time. Turns out the new ones are the same colour, I expected white. You can pick them up at zims autotechnik.
Please let us know how you made out changing the pads and chain. I did this job along with the cams last winter and I had a hell of time trying to compress the pads and installing the chains. I'm sure there is an easier way and was hoping to learn it.
Thanks
Those pads look pretty close to perfect to me. I don't see any wear compared to others who have posted pics here. Search a bit Durt - you'll find plenty of pics of cam pads, along with copious commentary, to help you calibrate your eyes.
And amazing shots as well. I feel like I'm at the Louvre.
So two chips in the top pic are not concerning? I kinda get the sense from reading about other peoples' misfortune that the pads get brittle and fall apart fast. I think my pads have reached the brittle stage (hence the chips), but they appear to be 99% intact. I've seen pics of failed pads. I'll keep looking for to see if I can find more pics in various stages of failure. Thanks for the input. I've been feeling a little sick thinking about pulling the cams on this car already. I tend to replace consumable parts (i.e. belts, rollers, etc...) when I do this kind of work, so I'm already thinking about it when I should be sleeping. Timing belt tools, variocam compressor, the stress of bending valves if I fail to line up cams, balancers and flywheel... oops, I think I just threw up in my mouth a little.
Its the bottom pad that is the concern, it can not be checked easily.
IIRC, it usually wears more than the upper pad.
You could try looking at it with a flash light and dental mirror.
I'd replace them with the chain for piece of mind.
i don't like the chipped tooth, and it is now a cleavage point for future fracture - keep an eye on that
1mm is a LOT for a groove in the pads - i believe the time to change is at about .5mm
but if your pads check out, and it is ok to run for a while, since the cams will need to come out for repair anyway, then you could probably wait to change them and the chain until the tooth breaks, as you will have to then remove the cams, along with your new chain - one broken tooth will probably not cause catastrophic failure unless it got jammed up somewhere it shouldn't, it could
based no the wear marks and coloring, it looks like somebody was using dyno oil - i would make sure you use the best synthetic oil you can to delay any such failure
A loose plug will make a mess. Several years ago I bought a 968. The dealer offered we drive it and we did. We drove it pretty had and back to the car lot where we cut a deal. Upon starting the car to drive it home it was running on three cylinders. We took it down the road a bit to try to clean it out but to no avail. Back to the car lot where the nice salesman said "sport it's yours now". I borrowed a plug wrench and pulled the plugs. #2 sparkplug was covered with oil from top to bottom. I was baffled. Top would say gasket. Bottom would say rings but why above and below the threads both? As I thought back while the plug took some effort to remove it there was no definate break loose when I started. I could only imagine that it was not absolutely tight and by driving it that hard we had forced compression by the plug and when that happened it sucked oil past the rings. We dried off the plug, put it back in and started the car. It ran normally. We drove it hard all 400 miles home. Upon arriving I checked again. Dry on top and bottom. I have owned the car for 30K miles and can drive the car from oil change to change without adding any oil at all. The plug just wasn't tight. Imagine the feeling in the pit of my stomach when I took that plug out the first time.
Just for clarification, the chip is in the top pad, not the cam tooth. The only wear I can detect on the cam teeth is by observing their shape. They are no longer perfectly symmetrical and appear to be rounding very slightly on the high tension side (see tooth photo). I don't think this will be a problem if I replace the chain soon. If it goes too long, I think they will shear or slip. I think these cams could go another 50K if properly cared for.
I agree that it's difficult to inspect the bottom pad well, but you can easily feel the bottom for chips with your fingers and there were none that I could tell. It's at least a way to convince yourself that the pads are intact. If there is a chunk missing, it will be simple to detect.
Can the pads be changed without taking the cam out? I saw in a previous thread that the chains can be broken at the rivets and re-pinned. If that is the case, can the variocam come out without the cams coming out? This would make putting a new chain in very simple. The Swede (Derek) that wrote the stellar article on inspecting the pads suggested the cams <b><i>must</i></b> come out.
i see a chip in a tooth in the pic above
<!--quoteo(post=82295:date=Oct 22 2009, 06:33 PM:name=durtkillon)-->QUOTE (durtkillon @ Oct 22 2009, 06:33 PM)
<{POST_SNAPBACK}><!--quotec-->Can the pads be changed without taking the cam out? I saw in a previous thread that the chains can be broken at the rivets and re-pinned. If that is the case, can the variocam come out without the cams coming out? This would make putting a new chain in very simple. The Swede (Derek) that wrote the stellar article on inspecting the pads suggested the cams <b><i>must</i></b> come out.<!--QuoteEnd--><!--QuoteEEnd-->
Yes, it can be done, and many will tell you the links and repinned rivets wiil be bound together with the same amount of strength as a new chain , and any crimping tool can do that, reconnecting the "broken" chain.. I for one, am not so sure you can rely on that school of thought 100% and sleep well at night.. russian roulette if you ask me.. [img]style_emoticons/<#EMO_DIR#>/dry.gif[/img]
I see what you are looking at Flash. I don't think that was actually a nick. It may be oil, but now I'm not 100% sure. That camera is sooo much better than my eyes were when I had my head in the car. I may look again this weekend.
I will probably be shredded for making this comparison, but I was a bicycle mechanic for years and broke (ie pressed the pins out) and installed thousands of chains. Using a chain extractor is very simple and very reliable. The only trick is getting the same amount of pressure on both outside plates when it gets re-assembled. If it doesn't, it will bind. The fix is to give the extractor an 1/8 of a turn from the other side. When breaking the chain, you only push the pin out 1/2 way and break the chain with two hands. If I could get my hands on the proper extractor, I will gladly try it and document it. I've got nothing to loose by trying except a weelend without my 968.
The thing that bothers me from my chian wrenching days is that a stretched chain usually meant the cogs were gone too. If I put a new chain on worn cogs, it would work some times, but it was usually loud or skipped. I don't know if that logic appies to cam sprockets since the chain doesn't have to pull diagonally like on a bicycle.
Ok, let the beating begin... I'm going to search for a timing chain extractor.
you can see where the outline shows a chip
no shredding - i still have a chain tool myself
I just inspected the cam sprockets, cam chain, and guide pads at 90K miles, and all looked good. However, I noticed what must be a sign of wear on the intake cam lobes. In the photo attached, it appears on the right side of the lobe face, presumably where it comes in contact with the tappet. The burnished area is smooth, not pitted. I'm wondering if this is an indicator of normal wear, or something to be concerned about.
[quote name='John' timestamp='1336685613' post='126805']
I just inspected the cam sprockets, cam chain, and guide pads at 90K miles, and all looked good. However, I noticed what must be a sign of wear on the intake cam lobes. In the photo attached, it appears on the right side of the lobe face, presumably where it comes in contact with the tappet. The burnished area is smooth, not pitted. I'm wondering if this is an indicator of normal wear, or something to be concerned about.
[/quote]
Looks normal to me , the lobes are normally not the concern on these cars , the teeth pads and chain are .
For the rest your head looks real clean , what did you do?? oil flush , rebuild ?? looks like new