Notices
924/931/944/951/968 Forum Porsche 924, 924S, 931, 944, 944S, 944S2, 951, and 968 discussion, how-to guides, and technical help. (1976-1995)
Sponsored by:
Sponsored by:

Early vs Late Belt Tensioner?

Thread Tools
 
Search this Thread
 
Old 05-16-2015, 01:26 PM
  #1  
Jim Chambers
Rennlist Member
Thread Starter
 
Jim Chambers's Avatar
 
Join Date: May 2001
Location: Bend, OR
Posts: 618
Received 13 Likes on 8 Posts
Default Early vs Late Belt Tensioner?

Am about to begin my first DIY cam belt replacement. Been doing lots of reading and watching trying to learn more. All online tutorials I have seen are for the earlier tensioning system. I have an '87 924S with the spring tensioner. Are there significant differences? Can anyone link me to info on the spring tensioner type?
Old 05-16-2015, 02:13 PM
  #2  
V2Rocket
Rainman
Rennlist Member
 
V2Rocket's Avatar
 
Join Date: Jan 2007
Location: Nashville, TN
Posts: 45,548
Received 648 Likes on 502 Posts
Default

it takes another step or two to put the new belt on, but the tensioner usually sets itself to the right amount.

let the tensioner go to full tension position and check the tension of the belt on the straight span from cam gear to crank gear, without the idler installed. you should be able to twist the belt no more than 90 degrees between thumb and index finger without too much effort. if you cant twist 90 degrees, use the balance shaft spanner wrench (or a 3/8 breaker bar fits into a slot in the tensioner arm) to back some tension off until you can. then lock the bolt/nut down, and check the tension again, and move on.
Old 05-16-2015, 02:18 PM
  #3  
Jim Chambers
Rennlist Member
Thread Starter
 
Jim Chambers's Avatar
 
Join Date: May 2001
Location: Bend, OR
Posts: 618
Received 13 Likes on 8 Posts
Default

Thank you Spencer. Do I understand that I don't need the expensive tensioner gauge to do the job?
That's what I would call technological progress!
Old 05-17-2015, 08:11 AM
  #4  
mikey_audiogeek
Three Wheelin'
 
mikey_audiogeek's Avatar
 
Join Date: Oct 2004
Location: Northland, New Zealand
Posts: 1,547
Received 8 Likes on 7 Posts
Default

Jim, there's a big difference in how you set the motor up before you release the tensioner. You DON'T wind the motor back 10 degrees from TDC.

Wind the motor in the direction of rotation to TDC and stop there!

Since the spring tensioner works in different fashion to the earlier setup, you're taking up the slack on a different part of the belt. This is why the different approach.

The factory workshop manual is a little cryptic, but the info is there: https://rennlist.com/forums/924-931-...l#post10804511

Cheers,
Mike
Old 05-17-2015, 10:59 AM
  #5  
Jim Chambers
Rennlist Member
Thread Starter
 
Jim Chambers's Avatar
 
Join Date: May 2001
Location: Bend, OR
Posts: 618
Received 13 Likes on 8 Posts
Default

Thank you Mike. The link leads to a very helpful thread and video I had not seen. I'm sure I will have more questions when I get into the project in a couple of weeks. Appears I don't absolutely need a gauge which is good news.
Old 05-17-2015, 10:05 PM
  #6  
mikey_audiogeek
Three Wheelin'
 
mikey_audiogeek's Avatar
 
Join Date: Oct 2004
Location: Northland, New Zealand
Posts: 1,547
Received 8 Likes on 7 Posts
Default

Hi Jim, yep it's one of those "easy once you know how" jobs.

I've always had good results checking the spring tensioner against the Arnworkx tool, enough to rely on the spring tensioner.

Of course you still need some way of setting the tension on the balance belt!

Cheers,
Mike
Old 05-17-2015, 10:46 PM
  #7  
Jim Chambers
Rennlist Member
Thread Starter
 
Jim Chambers's Avatar
 
Join Date: May 2001
Location: Bend, OR
Posts: 618
Received 13 Likes on 8 Posts
Default

So, I need the Arnworkx tool to set the balance belt?
Old 05-18-2015, 01:09 AM
  #8  
John_AZ
Proprietoristicly Refined
Rennlist Member
 
John_AZ's Avatar
 
Join Date: Oct 2001
Location: ~Carefree Highway~
Posts: 1,816
Likes: 0
Received 5 Likes on 5 Posts
Default

Originally Posted by Jim Chambers
So, I need the Arnworkx tool to set the balance belt?
Nah, I use the Krikit. Actually now I use nothing but the touch method for the balance belt.

I do back up the crank 5 to 7 degrees to set the cam belt using the 924S mechanical belt tensioner. But the final test is by touch--- cam belt pressure on the water pump pulley. You see, if the cam belt has too much pressure on the WP pulley, it will burn out the WP seal and bearing at some point.

The Arnnworx tool is a bargain for a beginner. $165 well spent. Lets you sleep at night and not wake up in a cold sweat.

J_AZ
Old 05-18-2015, 08:29 AM
  #9  
mikey_audiogeek
Three Wheelin'
 
mikey_audiogeek's Avatar
 
Join Date: Oct 2004
Location: Northland, New Zealand
Posts: 1,547
Received 8 Likes on 7 Posts
Default

Originally Posted by John_AZ
Nah, I use the Krikit. Actually now I use nothing but the touch method for the balance belt.

I do back up the crank 5 to 7 degrees to set the cam belt using the 924S mechanical belt tensioner. But the final test is by touch--- cam belt pressure on the water pump pulley. You see, if the cam belt has too much pressure on the WP pulley, it will burn out the WP seal and bearing at some point.

The Arnnworx tool is a bargain for a beginner. $165 well spent. Lets you sleep at night and not wake up in a cold sweat.

J_AZ
+1 for Arnnworx. Great product, great instructions, great support. Plus all the other tools you need for the job (pin spanners etc).

And +1 for the "can I sleep at night?" test!
Old 05-18-2015, 10:17 AM
  #10  
V2Rocket
Rainman
Rennlist Member
 
V2Rocket's Avatar
 
Join Date: Jan 2007
Location: Nashville, TN
Posts: 45,548
Received 648 Likes on 502 Posts
Default

Originally Posted by mikey_audiogeek
Jim, there's a big difference in how you set the motor up before you release the tensioner. You DON'T wind the motor back 10 degrees from TDC.
...do what now?
Old 05-18-2015, 08:38 PM
  #11  
mikey_audiogeek
Three Wheelin'
 
mikey_audiogeek's Avatar
 
Join Date: Oct 2004
Location: Northland, New Zealand
Posts: 1,547
Received 8 Likes on 7 Posts
Default

Originally Posted by V2Rocket_aka944
...do what now?
RTFM!

Pretty clear in the link I posted.

Cheers,
Mike
Old 05-18-2015, 09:02 PM
  #12  
V2Rocket
Rainman
Rennlist Member
 
V2Rocket's Avatar
 
Join Date: Jan 2007
Location: Nashville, TN
Posts: 45,548
Received 648 Likes on 502 Posts
Default

ahhh gotcha


you know i cant read
Old 05-19-2015, 07:19 AM
  #13  
Voith
Addict
Rennlist Member
 
Voith's Avatar
 
Join Date: Aug 2007
Location: Slovenia
Posts: 8,385
Received 648 Likes on 409 Posts
Default

Little bit of OT: which belt rollers are different between 8v and 16v engines?
Old 05-24-2015, 02:22 AM
  #14  
mel_t_vin
Rennlist Member
 
mel_t_vin's Avatar
 
Join Date: Apr 2006
Location: Dallas, San Francisco, Tampa
Posts: 2,103
Received 17 Likes on 16 Posts
Default

Originally Posted by Voith
Little bit of OT: which belt rollers are different between 8v and 16v engines?
SOHC and DOHC models use both a different [cam belt] tensioner roller and a different idler roller.

Balance belt tensioner/idler rollers are the same for all 944/S/Turbo.



Quick Reply: Early vs Late Belt Tensioner?



All times are GMT -3. The time now is 05:28 PM.