Tight Timing Belt?
05-27-2004, 08:17 PM
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Tight Timing Belt?
Last fall, I had my timing belt changed by a reputable mechanic in Orlando. The shop is owned by a former President of the Florida Citrus chapter of the PCA [Ron Zitza], and he was cool enough to let me spend the day in the shop watching and handing tools to the mechanic who did the job.
Well, several months later after finally managing to put 2000 miles on the car [work has been crazy, and I've spent most of the year away from home], I bought a timing belt tension gauge from 928 International and checked the tension.
-First of all, when I removed the passenger/left side timing belt cover, I noted that the belt appeared slightly scuffed on its surface- the words that are printed on the belt at the factory were rendered illegible, and thats about it to give you an idea as to how scuffed it was. I had the water pump changed, along with a tensioner rebuild and new pulleys, all parts from 928 Specialists in North Carolina. My new pump has a plastic impellor; the old one was metal, and Donnie told me he was sure that the pump that was removed was the original (!) with 133k miles!
Well, 2000 miles later I pull the timing belt cover and using the gauge...discover that my timing belt is not typically loose but actually slightly tight! I followed the instructions [which were VERY well worded and depicted; my MOM could have checked the tension on that belt with those instructions!] and did it three times; each time I came up with the same result: the belt is tight....
BUT OH so tight! Like, about a line-width tight. The aftermarket gauge I bought measures tension on the belt by twisting it; If the pointer falls between the lines it is correct. Each time I did it it was close...but just a hair tight.
Do you think it is worth the hassle of lifting the car, getting under there, loosening the bolt, backing off the tension...in order to fix this or is this tool's indication showing me a certain need? It's sooo "On the edge"-
That, and if I do retension it...any suggestions as to how many times the tensioner bolt should be turned to bring it just inside the range?
Normy!
Well, several months later after finally managing to put 2000 miles on the car [work has been crazy, and I've spent most of the year away from home], I bought a timing belt tension gauge from 928 International and checked the tension.
-First of all, when I removed the passenger/left side timing belt cover, I noted that the belt appeared slightly scuffed on its surface- the words that are printed on the belt at the factory were rendered illegible, and thats about it to give you an idea as to how scuffed it was. I had the water pump changed, along with a tensioner rebuild and new pulleys, all parts from 928 Specialists in North Carolina. My new pump has a plastic impellor; the old one was metal, and Donnie told me he was sure that the pump that was removed was the original (!) with 133k miles!
Well, 2000 miles later I pull the timing belt cover and using the gauge...discover that my timing belt is not typically loose but actually slightly tight! I followed the instructions [which were VERY well worded and depicted; my MOM could have checked the tension on that belt with those instructions!] and did it three times; each time I came up with the same result: the belt is tight....
BUT OH so tight! Like, about a line-width tight. The aftermarket gauge I bought measures tension on the belt by twisting it; If the pointer falls between the lines it is correct. Each time I did it it was close...but just a hair tight.
Do you think it is worth the hassle of lifting the car, getting under there, loosening the bolt, backing off the tension...in order to fix this or is this tool's indication showing me a certain need? It's sooo "On the edge"-
That, and if I do retension it...any suggestions as to how many times the tensioner bolt should be turned to bring it just inside the range?
Normy!
05-27-2004, 08:47 PM
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OK, so the pointer (ie., edge of the plate that engages the TB) is not centered in the notch: Just to clarify please the "line-width tight" - is any part of the pointer still within the notch? If so, how much? 50% of it's width, etc. Or, is the pointer beyond the notch by a 'line width'?
If it is still within the notch, and slightly on the tight side, there shouldn't be a problem. If beyond the notch, I'd be tempted to correct the tension.
Measure and adjust with a cold engine: A quarter to a half turn can make a signifigant change wheh close to 'ideal' - so it's good to counter hold the tension bolt firmly when loosening the lock nut: then loosen 1/4 turn for example, hold and snug the lock nut (both 17mm).
If it is still within the notch, and slightly on the tight side, there shouldn't be a problem. If beyond the notch, I'd be tempted to correct the tension.
Measure and adjust with a cold engine: A quarter to a half turn can make a signifigant change wheh close to 'ideal' - so it's good to counter hold the tension bolt firmly when loosening the lock nut: then loosen 1/4 turn for example, hold and snug the lock nut (both 17mm).
05-27-2004, 08:50 PM
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Normy... When it comes to belts:
924 drivers are concerned;
944 drivers are ****;
928 drivers are obsessive.
About 2,000 miles after my new belt
I checked it and it was just in the
window but off toward the loose mark.
I tightened it to 'center' of the window.
I'd say take the time to do it; the adjuster
might move a 1/4-1/3 turn or so, I'd guess.
Hard to say, for a hair, from 3,000 mi away.
G'luck.
924 drivers are concerned;
944 drivers are ****;
928 drivers are obsessive.
About 2,000 miles after my new belt
I checked it and it was just in the
window but off toward the loose mark.
I tightened it to 'center' of the window.
I'd say take the time to do it; the adjuster
might move a 1/4-1/3 turn or so, I'd guess.
Hard to say, for a hair, from 3,000 mi away.
G'luck.
05-27-2004, 09:13 PM
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the setting for the early engine was 4.5 on the Porsche dial indicator tension tool the later engines used 5. + 0.3 . I think yours should be at the very top of the window , as it is . The actual tension I believe is not as critical as it might first seem and cars have survived with it pretty far off . Several people have commented on belts that were found to be way off the scale and the car had thousands of miles . Obviously it is best to have it the way it was designed to run and the only way to know is measure it . The Kempf tool does a very good job and more importantly has enabled the belts to be checked hundreds of times .
05-27-2004, 10:12 PM
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Thanx Jim, Garth, and Macreel....
From what I can see at this point, I guess it isn't worth the work to readjust the belt. When I get home I'll yank that timing belt cover and post a pic so y'all can tell me if the scuffs on the top of the timing belt are normal...
Thanx again all!
N!
From what I can see at this point, I guess it isn't worth the work to readjust the belt. When I get home I'll yank that timing belt cover and post a pic so y'all can tell me if the scuffs on the top of the timing belt are normal...
Thanx again all!
N!
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06-13-2004, 10:46 PM
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Thanx again John!
I've pretty much decided that "a hair off" with this tool isn't going to cause a wrecked engine. I wonder if I might cause more harm than good by trying to re-adjust the belt, so I'm going to leave it be.
N!
I've pretty much decided that "a hair off" with this tool isn't going to cause a wrecked engine. I wonder if I might cause more harm than good by trying to re-adjust the belt, so I'm going to leave it be.
N!