cam chain slipper wear
12-30-2007 | 05:38 AM
#1
Thread Starter
Racer
Joined: Jul 2005
Posts: 364
Likes: 4
From: Sydney Australia
cam chain slipper wear
For those with 16v engines, I pulled my 100,000mls S2 3.0 engine down and thought you might be interested in the cam chain & tensioner measurements, this deveice links the two cams together. If this little unit fails your valves & pistons will meet and....
FYI there are two chain guide slippers on the cam chain one on top and one bottom made from some hard plastic/nylon material (I'm no chemist), the top one is about 0.16 thick, the bottom about 0.25, they both showed around 25 thou wear into the slippers, there has been comment about only replacing the top slipper it actually makes sense to do both especially as the percentage worn away is greater on the bottom.
Another point both slippers are VERY VERY brittle, so assuming this is caused by heating cycles, oil + age, I would replace both as a precaution anyway.
Also the chain was stretched to a point where the hydraulic tensioner was close to its top travel. The replacement chain is very cheap.
I am not sure whether my engine is typical, however the rest of the engine is in perfect condition, minimal wear.
Please consider on your next service to get these done if you are 100k + miles, for the sake of a $120+ in parts, chain + 2 slippers, this is sensible preventative maintanence. If money is plentiful replace the whole unit.
regards
mike
FYI there are two chain guide slippers on the cam chain one on top and one bottom made from some hard plastic/nylon material (I'm no chemist), the top one is about 0.16 thick, the bottom about 0.25, they both showed around 25 thou wear into the slippers, there has been comment about only replacing the top slipper it actually makes sense to do both especially as the percentage worn away is greater on the bottom.
Another point both slippers are VERY VERY brittle, so assuming this is caused by heating cycles, oil + age, I would replace both as a precaution anyway.
Also the chain was stretched to a point where the hydraulic tensioner was close to its top travel. The replacement chain is very cheap.
I am not sure whether my engine is typical, however the rest of the engine is in perfect condition, minimal wear.
Please consider on your next service to get these done if you are 100k + miles, for the sake of a $120+ in parts, chain + 2 slippers, this is sensible preventative maintanence. If money is plentiful replace the whole unit.
regards
mike
01-25-2008 | 05:37 PM
#2
Advanced
Joined: Nov 2007
Posts: 90
Likes: 1
From: Coral Springs,Fl.
Just some picture to show how these slippers can make for a bad day!!
http://www.944online.com/cgi-bin/for...num=1177680945
http://www.944online.com/cgi-bin/for...num=1177680945
01-31-2008 | 03:14 AM
#3
RL Community Team
Rennlist Member
Rennlist Member
Joined: Jun 2004
Posts: 11,014
Likes: 20
From: San Francisco Area
Not an S2, but from my 968. At 160k miles:
https://rennlist.com/forums/968-forum/405966-cam-tensioner-pads-at-160k-miles.html
It is fabled these can be changed without touching the timing belt or the exhaust cam at all. You can free the intake cam and swing it up, then jiggle the tensioner in and out.... Haven't tried it yet but it should work.
https://rennlist.com/forums/968-forum/405966-cam-tensioner-pads-at-160k-miles.html
It is fabled these can be changed without touching the timing belt or the exhaust cam at all. You can free the intake cam and swing it up, then jiggle the tensioner in and out.... Haven't tried it yet but it should work.
02-01-2008 | 04:54 PM
#4
Drifting
Joined: Mar 2007
Posts: 2,285
Likes: 0
From: Kansas City
Arash- I wouldn't try just taking out the intake cam by itself. When I had a broken intake valve spring, I thought I could replace it this way. Seemed easy enough. Pull one cam, replace the spring and put it back together, and not touch the timing. Wrong!
When I undid the cam, it started getting crooked, and when I took the caps off, the cam literally POPPED out of the journals in the head. It scared the living **** out of me. I then removed the exhaust cam and put them back in together. I wouldn't try and cheat the car here. I know it's a MAJOR pita to have to fiddle with all of that extra crap, but I wouldn't risk it. I'm lucky I didn't gouch a cap or journal.
As you can see, I pulled just one cam in this picture. The chain has tension on the cam, and when it starts to come out of the journals, the exhaust cam kind of pulls it toward it, and then it pops out when you remove the last cap. I would remove them both, equally undoing them at the same rate. Should really have the factory tools to remove the cams. They screw into the spark plug holes and hold both cams down while you undo the caps. You can do it without, but just be VERY careful.
On the other hand Mike, I'm cruious as to this chain stretch you talk about. I don't see how the chain can stretch that much. My tensioner pushes up pretty far, but don't think it's topped out. You sure the chain stretched, or this is just how it is? Did you compare new vs. old?
When I undid the cam, it started getting crooked, and when I took the caps off, the cam literally POPPED out of the journals in the head. It scared the living **** out of me. I then removed the exhaust cam and put them back in together. I wouldn't try and cheat the car here. I know it's a MAJOR pita to have to fiddle with all of that extra crap, but I wouldn't risk it. I'm lucky I didn't gouch a cap or journal.
As you can see, I pulled just one cam in this picture. The chain has tension on the cam, and when it starts to come out of the journals, the exhaust cam kind of pulls it toward it, and then it pops out when you remove the last cap. I would remove them both, equally undoing them at the same rate. Should really have the factory tools to remove the cams. They screw into the spark plug holes and hold both cams down while you undo the caps. You can do it without, but just be VERY careful.
On the other hand Mike, I'm cruious as to this chain stretch you talk about. I don't see how the chain can stretch that much. My tensioner pushes up pretty far, but don't think it's topped out. You sure the chain stretched, or this is just how it is? Did you compare new vs. old?
