I decided to break the balance shaft belt

I decided to break the balance shaft belt - Printable Version

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I decided to break the balance shaft belt - 968Syncro - 12-26-2012

Now, normally we say "the belt broke", but not in this case! I decided because.....

1. I haven't changed the belts within the recommended time.

2. I didn't pay attention to pending failure symptoms.

So Christmas Eve we are on the way to a party, a couple of hundred yards from home the belt blew (that is.... something went pop).

1. Periodic changes: last belt change was 7.5 years and 55K miles ago.

2. Symptoms: the past couple of weeks there was a sqeak-squeak sound, almost like an alternator bearing is going bad. It would go away once the engine was warm, no other symptoms. I was going to get to it any day now after the holiday busy period ended.

Then Xmas eve the car suddenly started full time loud squeaking / howling. Before I could gather my thoughts there was a loud pop and a bit of smoke surfaced from under the hood. It kept running for a couple of seconds to get to the side of the road and I turned it off. Yesterday I looked and could see a bit of a toothed belt lying on the top of the bat wing. But also I could see the cam belt in place in the little inspection hole on the distributor. All the accessory belts were fine and in place.

Sweating bricks about broken cam belt and bent valves!!! So towed to the shop today. Whew!!! Dodged a bullet -- it is only the balance shaft belt, didn't affect the cam belt, cam belt looks good, and the timing was still correct. So we are putting the whole belt kit in with the new rollers. There is no oil seepage. Water pump was replaced about 8 years ago. So it is only the belts/rollers, no new water pump, no new hydraulic tensioner, no new seals. With a couple of others things while open, estimate it will all come in under $1,000.00

Change your belts -- this will happen if not!

I decided to break the balance shaft belt - 968Syncro - 12-26-2012

Footnote: Yesterday I spent a lot of time studying the forum and workshop manual thinking I could do this myself. But this time I'll go with a pro -- the shop owner drives a 968 and has done this procedure a few times, and of course works on 911s, Cayennes, certified Porsche mechanic. I need the car back and it would have likely taken me many days or a couple of weeks assuming I didn't screw something up which could get very costly.

There is a fairly good balance shaft belt DIY here: http://www.968forums...lt-replacement/ but without pictures. I would do this myself the next time, in about 3 years, buy a couple of tools as needed, hoping Flash will do the belts DIY some day since that would be very much appreciated and certainly would lift my confidence on doing this job.

I decided to break the balance shaft belt - MB968 - 12-26-2012

I'd add the timing belt tensioner. If it fails, you are likely to bend valves. With all you are doing another $170 is mighty cheap insurance that the job will last.

I decided to break the balance shaft belt - craigawoodman - 12-26-2012

Given how old the water pump is - wouldn't it be a good idea while you are in there?

I decided to break the balance shaft belt - Cloud9...68 - 12-26-2012

The water pump is always a tough call. However, remotecontroller has a new one for sale for $120 (see his thread on miscellaneous 968 parts for sale), which might be worth considering.

I decided to break the balance shaft belt - MB968 - 12-27-2012

On the water pump, if it isn't leaking that's a good sign, not only meaning that the seal is OK, the shaft under the seal is smooth, and also likely means that there is little slop/wear in the bearings (which can lead to a leaky seal). Do one other thing, slowly rotate the bearing putting some pressure on it. One early sign of bearing degradation is roughness when you rotate it caused by a ball (or roller) passing over a pit in the race.

Here's my reasoning on the tensioner: Unlike a lot of the other parts which will create some kind of noise as you experienced, or will get rough as with a bearing which is on it's way out, you won't be able to tell if the tensioner is degrading. You'd have to be able to test it with a load meter, or the like. That's why I always replace them at least every 50 - 60k miles or sooner if I see any signs of leakage/looseness, etc of the push rod.

I decided to break the balance shaft belt - Eric_Oz_S2 - 12-27-2012

I'm about to change my belts and rollers, and will be doing this myself again. It is really not that hard a job to do, and you will save yourself hundreds of dollars. A belt and roller kit is around $300. For me it is a 3 year interval replacement.

I decided to break the balance shaft belt - tamathumper - 12-27-2012

Holy crap. Congratulations on dodging a bullet.

I decided to break the balance shaft belt - Remotecontroller - 12-27-2012

[quote name='Eric_Oz_S2' timestamp='1356591943' post='136664']

I'm about to change my belts and rollers, and will be doing this myself again. It is really not that hard a job to do, and you will save yourself hundreds of dollars. A belt and roller kit is around $300. For me it is a 3 year interval replacement.

[/quote]

I bought a continental belt kit on Ebay for $269 (with free shipping). Great deal and all went well!!

I decided to break the balance shaft belt - flash - 12-27-2012

remote - oof - i would not have installed contitech. you'll be in there sooner than if you had gone gates. conti stretches too much, and cross-links too easily. make sure you retension the balance shaft belt every year to attempt to avoid this problem. it's something everybody should be doing anyway, but especially if you have conti belts.

synchro - welcome to the bullet dodging club. i had my balance belt fail on me a few years ago at the beginning of one of the paso robles runs. i'm glad i pulled over and removed it before it got tangled up in there and really screwed me, but it was not a good feeling to drive all the way to paso robles and back with that belt off the car.

I decided to break the balance shaft belt - Scott Collins - 12-27-2012

968Syncro,

Pretty unusual for one of the balance belts to fail - they are fairly robust.

If you had screeching, check to see if one of the bolts holding the lower belt guides has backed out. I had this happen to me once, and it came into contact with the belt, leaving a gouged groove in the belt. Caught it before the belt broke, but not before

shredded belt material was everywhere.

The remedy was a new belt and Loctite on the threads of the bolt to keep it in place, which I should have done initially anyway. I also cleaned everything up and all was good.

Good luck.

Scott

I decided to break the balance shaft belt - flash - 12-27-2012

it's actually not that uncommon. when they get loose, they tend to jump around. they start that way to begin with, so it's not a big leap to being too loose.

if you're lucky when that happens, it only jumps a tooth. if you aren't so lucky, they can get into harm's way.

in my case, it moved to the edge and caught the edge of one of the retaining washers. that washer essentially split the belt longitudinally. this all happened because i failed to heed the owner's manual and re-tension my balance belt every year.

I decided to break the balance shaft belt - 94SilverCab - 12-27-2012

Syncro - Bad choice...I'm a non-survivor of the dreaded TB/BS belt snap, bent valves, etc club..no joy.

Hope you get it back on the road quickly.

Jay

I decided to break the balance shaft belt - Cloud9...68 - 12-27-2012

I had a BS belt shear a bunch of teeth a few years ago. Don't know what brand it was, but it was the wrong size - it was too narrow (probably a 944 belt), and consequently didn't fit all the way across the rollers, and probably "walked" quite a bit, causing it to fail. Fortunately, it didn't get tangled up in the timing belt.

I decided to break the balance shaft belt - Scott Collins - 12-27-2012

This is all reminding me that it's been a while since I checked the tension on MY balance belt.

I going to go out on a limb here. Failing to heed the owner's manual has probably caused many (of maybe even most) of the problems ever experienced on the 968.

I decided to break the balance shaft belt - Grandpa#3 - 12-27-2012

Since all are talking about the Cam and Balance Belts. I'll stick with the old 944 rule on belts. Replace every three years or 30K miles which ever comes first. A friend of my sons 968 had his Cam Belt chewed up by the Rear Cam Gear Housing coming apart cutting up the belt. Needless to say, BENT VALVES, Rear Cam Housing replaced along with complete front end/head work, cams insp., chain and pads replaced, ect., you get the idea WYIT type work. He was able to get a new Rear Cam Housing from Sunset for $700. Those things are as scares as hens teeth. My son did all the work for him and he is back on the road again. It's nice to have a Porsche trained mech in-house, all it cost me is parts. Lesson to be learned here is to CHECK the Rear Cam Gear Housing for De-lamination / Falling Apart. Porsche did make some out of aluminum but they did not hold up for some reason and Porsche went back to Magnesium Housings.

Cheers,

Larry

I decided to break the balance shaft belt - 968Syncro - 12-27-2012

[quote name='Grandpa#3' timestamp='1356655821' post='136704']

It's nice to have a Porsche trained mech in-house, all it cost me is parts.

[/quote]

Can your son train my son? <img src="/forum/images/smilies/968/smile.png" class="smilie" alt="" />

I decided to break the balance shaft belt - Grandpa#3 - 12-27-2012

I think it would be just a little too far for him to travel. It might be cheaper to send your son to school. Porsche is building a new plant just south of Atlanta with their own 3 mile race track proving ground. It is supposed to be fantastic when finished. I believe the Southeast Region PCA will have access to it when finished.

Cheers,

Larry

I decided to break the balance shaft belt - 968Syncro - 12-28-2012

Picked it up today.

The Good: runs fine, price seems right.

The Bad: a dent in the hood with chipped paint, mechanic must have closed it with a tool or part laying on the valve cover. A clear scrape is visible on the underside. <img src="/forum/images/smilies/968/whine.gif" class="smilie" alt="" />

He will take care of the repair. Called his buddy at a nearby auto body place and I went by and made an appointment. It will need a bit of dent pounded out, prime, paint, clear coat. The auto body place looks good judging from the nicer cars there. It stinks, I think he knew about the problem but didn't speak up until I pointed it out. Not sure I'll be going back there soon.

Roland

I decided to break the balance shaft belt - tamathumper - 12-28-2012

Quote: I think he knew about the problem but didn't speak up until I pointed it out. Not sure I'll be going back there soon.

To say the least! <img src="/forum/images/smilies/968/ohmy.png" class="smilie" alt="" /> Sorry for your troubles.