adjusted the belts on my turbo..

nynor · 11-04-2005, 05:33 PM

what a pain in the arse!!! way tighter than my '83, more stuff to pull off, and i had the proper tool! took me 2 hours how to use the thing properly, then jumped a tooth on the timing belt!

i got it all back together and it works, so i am not complaining. good for another 5K miles or so.

Porsche-O-Phile · Porsche-O-Phile's Garage

Whaddya' mean it jumped a tooth? If it jumped, you probably didn't have it tensioned properly - either that or you forgot to tighten something.

Zero10 · 11-05-2005, 08:41 AM

Jumped a tooth, did you try and turn it by the cam?
I did that once, it actually jumped about 3 in a row...
Good thing I was just rotating the engine by hand, and it wasn't running

I hate tensioning the belts on a turbo. I've done it on 3 944's, and on 1 951. I would rather do all 3 944's than 1 951, lol.

What do you mean good for 5k miles?..
As a rule, you tension the belts when they're installed, then re-tension at 2000 miles. From there, you check the tension yearly, replacing at the specified mileage or age limit (I think 40k miles, 4 years?.. I don't remember off the top of my head)
Unless you mean you drive 5k miles a year, then that's just right

AaronM · 11-05-2005, 08:45 AM

Quote:

Originally posted by Zero10
Jumped a tooth, did you try and turn it by the cam?
I did that once, it actually jumped about 3 in a row...
Good thing I was just rotating the engine by hand, and it wasn't running

I hate tensioning the belts on a turbo. I've done it on 3 944's, and on 1 951. I would rather do all 3 944's than 1 951, lol.

What do you mean good for 5k miles?..
As a rule, you tension the belts when they're installed, then re-tension at 2000 miles. From there, you check the tension yearly, replacing at the specified mileage or age limit (I think 40k miles, 4 years?.. I don't remember off the top of my head)
Unless you mean you drive 5k miles a year, then that's just right

3 years, 30,000 miles for the expected belt life. Tension at initial install, 2,000 miles, and 15,000 miles. Replace at 30,000.

IanS · 11-05-2005, 10:54 AM

I have to assume most people don't retension the timing belt at 2k and 15k, since its not totally necessary. My belt was replaced 15k ago by the PO, so its probably time to retension it.

Are there symptoms of it not being tensioned properly, or does proper tensioning 'just' reduce the chance of engine damage?

Britwrench · 11-05-2005, 11:32 AM

"since it's not totally necessary" .....good idea, my holiday home in Tahiti will be paid for sooner!!!

The factory recommendation is: adjust 2000-2500 miles from installation, check and re-adjust every 15,000 miles (which is when the factory maintenance service is anyway).

Loose belt = broken belt = money for the repair shop... or now your 944 is worth $500

AaronM · 11-05-2005, 11:42 AM

Quote:

Originally posted by IanS
I have to assume most people don't retension the timing belt at 2k and 15k, since its not totally necessary. My belt was replaced 15k ago by the PO, so its probably time to retension it.

Are there symptoms of it not being tensioned properly, or does proper tensioning 'just' reduce the chance of engine damage?

There is just a spring tensioner for these cars, it's not that great... Best to adjust the tension. Small price to pay for piece of mind.

Aaron

IanS · 11-05-2005, 11:53 AM

Its clearly not totally necessary, because cars run without retensioning the belt. And people ignore the factory recommendation on a whole variety of things. I'm not intending to ignore it, I'm just assuming its typical of many owners, particularly since these cars are getting a bit older.

I'm assuming the PO of my car did not have the belt retensioned at 2k miles, both because I don't have a receipt for it and because I tend to assume people are lazy. For that matter, I would guess that a lot of mechanics just take a look at the belt at 15k, and if it looks pretty tight, don't bother to touch it.

I was actually intending to have mine tensioned in the near future.

I'll ask the obvious question. Why aren't the timing belts auto-tensioned in some way? I know all auto-tensioning systems have failure modes as well, but most timing belts on other cars last for about 60k-100k and don't have to be retensioned.

bryanthompson · bryanthompson's Garage

being platinum member of the Order of the Bent Valve, I'll take the advice of the pro's on this board and continue tensioning at factory specified intervlals. To not do it seems incredibly foolish.

Zero10 · 11-05-2005, 05:52 PM

With the spring tensioner, belt tension should be checked at 2000 and 15,000 miles, most likely not adjusted. With the manual tensioners, you will usually find that the belt tension is out of spec at the 2000mile check. I've seen some that stretched out so far that they didn't register on the 9201, and some that didn't stretch at all. Of course, there have been a handful that were exactly on spec at the 2000 mile check, but far fewer than there were overtensioned, or undertensioned. For those that are overtensioned, that's just begging for a timing belt failure.

Your argument that it's not totally necessary holds, but at the same time, changing your transmission fluid isn't totally necessary, because I've seen cars that have gone 500,000km on their original fluid, but would you do it?...
I've seen cars go over 100,000km on an oil change, but would you do it?...
I will retension my belts at 2000 miles, and check them yearly

IanS · 11-05-2005, 07:12 PM

Clearly my original statement came off wrong, but my basic point was it seems like something most people would overlook. Like how some people never change their transmission fluid and their fuel filter.

On my 1988 951, I have the spring tensioner, so it should be checked, but probably wont' need to be retensioned.

bigyagi · bigyagi's Garage

the timing belt tension issue, is almost as popular as"how do i turbo my na"
from reading posts from people who have had the belt break, and now religiously adhere to factory specs etc, i decided about 1 year after getting my car, that this was the most important service item, because if not followed out, the cars value could go to almost scrap value in a moment. yes, i use the krikit, and have had no problems. i still maintain, that even owning the p9201 tool, is still no guarantee, that a belt will not break at some stage. anything that is mass produced, or produced by a process, will at some stage suffer from murphys law. we all know about the "friday" car. believe me, the same is true of belts. at some stage, someone will buy a belt that slipped{no pun intended} thru the quality control, or has been sitting in some damp warehouse, for ever. its the luck of the draw. all you can do, is fit said belt, and hit the mark. try not to "give" it a little more for luck etc etc. 2k later, retension, then 15k. throw away at 30k. with the timing belt being so inexpensive, and not a time-consuming job at all, its best to be safe!
just my .02c worth.

nynor · 11-06-2005, 08:21 AM

the belt jumped a tooth because, being the donut that i am, i was rotating the engine backwards, at the crank (don't ask!) and it jumped a tooth. luckily it was only one and i was able to set it right by reducing tension at the spring, pulling the belt off of the cam pulley, and rotating the cam back a tooth.

5K miles? that is because i am paranoid. i'll probably dig in there about every two months just to look at it and make sure things are looking right. about every six months i'll actually put the 9201 on it.

Dougster · 11-06-2005, 08:49 AM

Mine was last done 20k miles ago...But now I want a TURBO again...

IanS · 11-06-2005, 10:31 AM

Anyone ever used the Arnnworx AWX tensioner he just came out with? http://www.arnnworx.com/tensioner.htm

People seem to complain quite a bit about the Kricket tool and I'm not willing to pay $600 for a single tool, so I was thinking this might be a good alternative. It does look fairly idiot-proof, which would be nice for my first time checking the tension.

nynor · 11-06-2005, 10:59 AM

the cricket is going to be tough on your '88 turbo. it worked great on my '83, but the '88 has a belt guard that i couldn't remove without moving the belt tensioner. which means that after i set it with the kriket, i'd have to move the belt tensioner to get the guard back on, obviating the tensioning i just checked!

i bet you can find someone in CA that will rent you their 9201.

Porsche-O-Phile · Porsche-O-Phile's Garage

Do the retension. Trust me on this. As good as the belts are, they do stretch a little after initial install. I currently have my n/a ripped apart for retension (and a couple other things) in my garage. When I pulled the belt covers off, the tension of the balance shaft belt had dropped from 28 to about 23 pounds and the cam belt from 40 to about 35 pounds. This is slightly low and after about 3,500 miles of driving. Both were absolutely balls-on when I did the initial installation as well. . . So it does happen. Whether they would have gotten any looser is a good question.

rb101 · 11-07-2005, 02:49 PM

I had the locknut come loose on the spring tensioner after about 300 miles. The belt was slapping around in the cover. Needless to say I quickly put on a new locknut with loctite to be sure it does not come loose again. At the 1500 miles it did need a good retension.