Timing Belt Wear Question UPDATED 2-4-07
02-02-2007, 10:45 AM
#61
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Hi Gang,
First: I agree this TB is not new, no way. If a TB shows that much wear after 1500 miles, it would have produced some sort of noise and would have failed 5 miles later.
Second: I had a lot of fun in my old job at Sheppard AFB. One of my duties was to proof read USAF officer performance reports. The look on some faces after I rejected reports due to grammar: PRICELESS
First: I agree this TB is not new, no way. If a TB shows that much wear after 1500 miles, it would have produced some sort of noise and would have failed 5 miles later.
Second: I had a lot of fun in my old job at Sheppard AFB. One of my duties was to proof read USAF officer performance reports. The look on some faces after I rejected reports due to grammar: PRICELESS
02-02-2007, 02:22 PM
#62
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Hi Schocki
Reminds me some years ago I did a project for the British RAF with a big technical team.
The last deliverable to a tight time schedule was a user manual. None of the team could write so the content of the manual was awful.
I delivered it to the Project owner who handed it over to Quality man. His report was,
Font Correct
Font size Correct
Line spacing Correct
Paper size correct
Grammar Correct
Manual is 100% OK.
Marton
HTML Code:
Second: I had a lot of fun in my old job at Sheppard AFB. One of my duties was to proof read USAF officer performance reports. The look on some faces after I rejected reports due to grammar: PRICELESS
Reminds me some years ago I did a project for the British RAF with a big technical team.
The last deliverable to a tight time schedule was a user manual. None of the team could write so the content of the manual was awful.
I delivered it to the Project owner who handed it over to Quality man. His report was,
Font Correct
Font size Correct
Line spacing Correct
Paper size correct
Grammar Correct
Manual is 100% OK.
Marton
02-02-2007, 02:22 PM
#63
Drifting
Join Date: Nov 2001
Location: zürich, switzerland
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Hi Schocki
Reminds me some years ago I did a project for the British RAF with a big technical team.
The last deliverable to a tight time schedule was a user manual. None of the team could write so the content of the manual was awful.
I delivered it to the Project owner who handed it over to his Quality man. His report was,
Font Correct
Font size Correct
Line spacing Correct
Paper size correct
Grammar Correct
Manual is 100% OK.
Marton
HTML Code:
Second: I had a lot of fun in my old job at Sheppard AFB. One of my duties was to proof read USAF officer performance reports. The look on some faces after I rejected reports due to grammar: PRICELESS
Reminds me some years ago I did a project for the British RAF with a big technical team.
The last deliverable to a tight time schedule was a user manual. None of the team could write so the content of the manual was awful.
I delivered it to the Project owner who handed it over to his Quality man. His report was,
Font Correct
Font size Correct
Line spacing Correct
Paper size correct
Grammar Correct
Manual is 100% OK.
Marton
02-04-2007, 12:48 PM
#67
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Timing Belt Removed - New Pictures
I removed the TB covers on Friday and took some interesting pictures.
It is possible that only the WP & TB were changed and nothing else and I mean nothing else!
The WP looks new, however if the TB was new it certainly experienced some serious wear in a few miles.
At 45 BTDC the timing marks were lined up perfectly. Prior to removing the TB the tension was spot on.
The belt is tracking forward on the right side cam gear and rubbing against the roller arm.
Both the idler and tensioner pulleys show uneven wear.
The pivot bolt looks straight to the eye.
All the bolts & washers seem to be in the right place.
What is causing the belt to track forward or at least be positioned forward and the uneven wear on the rollers?
Looking forward to hearing your thoughts.
Car is an 86,5 with 60k miles.
It is possible that only the WP & TB were changed and nothing else and I mean nothing else!
The WP looks new, however if the TB was new it certainly experienced some serious wear in a few miles.
At 45 BTDC the timing marks were lined up perfectly. Prior to removing the TB the tension was spot on.
The belt is tracking forward on the right side cam gear and rubbing against the roller arm.
Both the idler and tensioner pulleys show uneven wear.
The pivot bolt looks straight to the eye.
All the bolts & washers seem to be in the right place.
What is causing the belt to track forward or at least be positioned forward and the uneven wear on the rollers?
Looking forward to hearing your thoughts.
Car is an 86,5 with 60k miles.
__________________
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014
928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
02-04-2007, 01:01 PM
#68
Supercharged
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My bet is a bent tensioner pulley bolt. At least I think that's the bolt - it's the one that BigDave found as the cluprit for his TB failure as well as a few others.
02-04-2007, 01:10 PM
#70
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Andrew,
The bolt looks perfectly straight with a steel rule - how bent are we talking?
Garth,
No play on the tensioner roller in either plane.
There is some slight wear in the two non metallic bearing inserts where the pivot bolt passes through.
Maybe .015" total. They will be changed.
The bolt looks perfectly straight with a steel rule - how bent are we talking?
Garth,
No play on the tensioner roller in either plane.
There is some slight wear in the two non metallic bearing inserts where the pivot bolt passes through.
Maybe .015" total. They will be changed.
02-04-2007, 01:33 PM
#71
Rennlist Member
Check the plastic bushings in the Tensioner arm where the shoulder bolt pictured passes thru. If the shoulder bolt is straight it is probably worn bushings. It Could also be that the tensioner arm is bent but i doubt it.
02-04-2007, 01:35 PM
#72
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Sterling,
Everything is being replaced - just trying to understand what happened in the first place.
The idler bearing has a small amount of play - maybe .025" total. Definitely on its way out.
Whats amazing is that IF the WP is new they took the idler pulley of the old one and put it on this one with the wear in the bearing - negligent in the first degree!
Roger
Everything is being replaced - just trying to understand what happened in the first place.
The idler bearing has a small amount of play - maybe .025" total. Definitely on its way out.
Whats amazing is that IF the WP is new they took the idler pulley of the old one and put it on this one with the wear in the bearing - negligent in the first degree!
Roger
02-04-2007, 01:44 PM
#74
Rennlist Member
Originally Posted by ROG100
Ben,
See post #70.
Roger
See post #70.
Roger
Here are some pictures of the bushing in the tensioner arm that failed causing all the damage. The pictures arent the best, basically the bushing cracked and ovaled out which alloud the tensioner to rock in relation to the rest of the pulleys pushing the timing belt forward into the tensioner bracket (thats what the shiny silver grooves in the arm are, the belt cut them in)
http://www.lasotaracing.com/carter/broke/ten1.jpg
http://www.lasotaracing.com/carter/broke/ten2.jpg
http://www.lasotaracing.com/carter/broke/ten3.jpg
http://www.lasotaracing.com/carter/broke/ten4.jpg
http://www.lasotaracing.com/carter/broke/ten5.jpg
Here are pictures of what it looked like with the belt still on it, you can see how the pulley is cocked at an angle to the crank pulley...
http://www.lasotaracing.com/carter/broke/al1.jpg
http://www.lasotaracing.com/carter/broke/al2.jpg
http://www.lasotaracing.com/carter/broke/al3.jpg
http://www.lasotaracing.com/carter/broke/al4.jpg
http://www.lasotaracing.com/carter/broke/al5.jpg
And this is the end result
http://www.lasotaracing.com/carter/broke/result1.jpg
http://www.lasotaracing.com/carter/broke/result2.jpg
http://www.lasotaracing.com/carter/broke/result3.jpg
The driver side head has all the exhaust valves bent severely, the passenger side isn't as bad, but they still need all new exhaust valves and guides...
bunch of Porsche valvetrain parts... http://www.lasotaracing.com/carter/broke/parts.jpg