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Another S4 chain tensioner pad R&R for posterity

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Another S4 chain tensioner pad R&R for posterity

 
 
Old 08-18-2009, 05:35 PM
  #16  
Landseer
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Is there a chatter or other noise that indicates wear? If so, would it be on start up? (85)
And thanks for the write up and comments.
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Old 08-18-2009, 07:28 PM
  #17  
the flyin' scotsman
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Originally Posted by Landseer View Post
Is there a chatter or other noise that indicates wear? If so, would it be on start up? (85)
And thanks for the write up and comments.
I never noticed any noise improvement after changing the pads but the '88 tensioners are oil pressured..

I changed mine because I had the cam covers off to replace gaskets and also recalled reading where a Lister had a pad break while engine was running with nasty effect (big Dave maybe?)
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Old 08-18-2009, 07:42 PM
  #18  
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Another nice write up Rob.

Where do you find all the time?

Keep going... It gives me hope...
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Old 08-18-2009, 07:58 PM
  #19  
Rob Edwards
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Mike-

Rennlist isn't 'complete 'till there's a good DIY writeup for R&R'ing every component/system on every MY 928 written and illustrated in a way that even I can understand. We're still a long ways off!

3 young kids + a wife who's on call 25% of the time = Lots of evenings stuck at home guarding kiddos who are asleep. I can't work doing science ALL the time....
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Old 08-19-2009, 12:01 AM
  #20  
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Here's the pics of the pre-86.5 tensioner with the huge spring:



The black pad is screwed into the moving piston part of the tensioner with odd screws that are grooved.



The tensioner also looks like it oils the chain through the pad - there's a hole in the center that is fed by the banjo fitting through the center of the piston.

No part numbers on any of it, including the underside of the removable pad - so presumably you have to buy the whole assembly from Porsche as a unit, including both pads?
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Old 09-27-2010, 01:42 AM
  #21  
Ed Scherer
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Thanks for your write-up in post #1, Rob.

I just replaced all of my pads this weekend.

Question: how is the air bled off after you do this procedure and the tensioner has no oil in it? Is the chain loose (and maybe noticeably noisy) for awhile at the next startup? I didn't really inspect the tensioner that carefully to see if maybe it had a tiny air bleed hole somewhere.
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Old 09-27-2010, 02:05 AM
  #22  
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No need to bleed. It will pump up when the oil starts flowing.
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Old 09-27-2010, 12:17 PM
  #23  
Ed Scherer
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Thanks, Andrew.

Another question: Does it bother anyone else that there all of these cam chain tensioner related bolts are all installed without lock washers or Loctite and are in an oil soaked environment and only torqued to 10 Nˇm? I'm just thinking of all those self-loosening oil pan bolts and wondering if anyone has ever had one of these bolts back out? Seems like it could be catastrophic.
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Old 09-27-2010, 12:27 PM
  #24  
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I'm not worried. They were torqued that way on every 928 from the factory and some are still undisturbed years and 100k's miles later. Also, you *really* don't want to over-tighten banjo bolts.

Dan
'91 928GT S/C 475hp/460lb.ft
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Old 09-27-2010, 12:29 PM
  #25  
soontobered84
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Originally Posted by Ed Scherer View Post
Thanks, Andrew.

Another question: Does it bother anyone else that there all of these cam chain tensioner related bolts are all installed without lock washers or Loctite and are in an oil soaked environment and only torqued to 10 Nˇm? I'm just thinking of all those self-loosening oil pan bolts and wondering if anyone has ever had one of these bolts back out? Seems like it could be catastrophic.
Man, I was just thinking that same thing.
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Old 09-27-2010, 01:24 PM
  #26  
Ed Scherer
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Originally Posted by dprantl View Post
I'm not worried. They were torqued that way on every 928 from the factory and some are still undisturbed years and 100k's miles later.
As a first timer on this stuff, I worry about things I'm ignorant about. This is one of many.

Threads like "Found all the missing pieces in an oil passage....*pics*" (and the related "Look what I found in my oil pan...") don't help. Look at post #28 in that first thread, where Lizard931 posits, "from the looks of the piece that broke off, it looks to me like the bolt backed out and then got chewed up."

Originally Posted by dprantl View Post
Also, you *really* don't want to over-tighten banjo bolts.
Yeah, I'm sure that the head popping off probably wouldn't be a real good thing, either.

Originally Posted by soontobered84 View Post
Man, I was just thinking that same thing.
ESP. Ooooooooooooo.


BTW, I posted a few more tips on tensioner pad replacement in another thread.
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Old 09-27-2010, 02:38 PM
  #27  
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Yeah 10Nm seems awfully light, but mine's been fine for 3 years.
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Old 10-06-2010, 05:54 PM
  #28  
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Hey, one final question on the cam chain tensioner (it's my last shot at this for a long while, I hope, as I'm finally putting my covers back on within the next couple of days):

PET (for 87-91 MY) shows the following. Note washers identified as #16 (part number N0115247).

My tensioner bolts (#15) did not have the washers (#16) between the bolts and the tensioner as shown in the diagram. Normal, or not? Do I need to add them?

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Old 10-06-2010, 09:00 PM
  #29  
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#15, per PET, calls for a M6x22mm bolt. #16 is just a flat washer (probably to keep the bolt from bottoming out, but could also be due to the bolt land). I'm guessing the bolt installed on your car is M6x20mm, thus no washer installed.

Did you measure the bolt length before the reinstall and torque per WSM specified value?

You could use a thread locker compound. A blue one wouldn't hurt.
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Old 10-12-2010, 04:26 PM
  #30  
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For the record, the cap head bolts for the tensioner were M6 × 18 mm.

I went back to the photo that Rob included in post #1 of this thread and did a quick cross-check on a crop that included just one of the bolts:

Name:  CamChainTensionerBoltDimensions.gif
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The blue line across the bolt should be about 6 mm long (it's an M6 bolt!). I cloned that line three times and laid the clones end to end (offset a little so they're distinguishable) along the length of the bolt. Since (heavy-duty advanced math here) 3 × 6 mm = 18 mm, I believe that Rob's bolts were also M6 × 18 mm. And Rob's photos didn't show any washers for these bolts, either, so I'm concluding that mine was as the factory installed it and that this is normal.



They also got a little surface-insensitive (oil-resistant) blue threadlocker (Permatex 24300; equivalent, I believe, to Loctite 243). I just couldn't sleep well without doing that.

Regardless, what's done is done; everything is now buttoned up, hopefully, not to see daylight for a long, long time.
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