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Cams and Belts! The good news and bad.
#1

As the tiptronic is showing over 130,000 miles and all the talk about the sprocket wear on some cars i thought i would take down the cam covers and check the sprockets chain and pads.

all is Ok as the pictures show.



   



Great news so i thought i would check the cam belt through the inspection hole looks good.

Then i thought about the slight and very slight vibration on a fast idle which i querried on purchace with the seller,He put me through to the specalist who had just serviced the car and said all was serviced and all ok.

Refrence my post here 19/5/07 after purchace.



May 19 2007, 11:16 AM

Post #9





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All go in the garden, but i have today bought the cab 968 tiptronic, so now i have two.

Same colour and speck apart from the auto box.

Needs another roof but has one other prob that i noticed,will put a new posting"Engine vibration" for any suggestions.



I thought i would undo a few cover bolts and check the balance shaft belt for tension cripes this is what i found.



   



Yep the belt was snapped and i have been stokeing the old girl around in all manner of rev's all this time.

How lucky that it never moved into the cam belt.

Well i will be doing a total belt replacment and with no special tools i will keep you posted on any probs that may arise, with pictures.



The other problem that may help anyone who has suffered loss of water in different amounts was the slight drip from the plastic fitting on the water pump.

I feel i am so lucky to what could be blamed on a cam belt failure if the broken belt had picked up.
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#2

Wow! Scary-lucky indeed.
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#3

Yes you are very lucky,



For the best change all the rollers, belt and waterpump!. by a new one or a rebuilt from Porsche.

Brand new rebuild with Porsche warranty and half the price of a new one.
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#4

Thanks for the info,looks like the pump is ok.the main cam cogged tensioner rollers have wear and also the top belt guide roller but the rest are ok including the tensioner damper.

From looking at the balance shaft belt guides it looks as if the belt was run on the slack side.

Before i removed any thing on the cam belt i set the cam pulley mark to the mark on the cover.

The crank pulley did not have any marks so have centre popped some.

Will make note of all the adjuster positions.

Any comments and advise welcomed.



   

Cam pulley and cover marks.









   

Crank pulley and cover centre popped.







   



This was the varrible water leak.

Replaced the o ring and fitted with rubber lube after a good clean up.

Waiting for the parts to arrive before i can do much more.
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#5

[quote name='winger' post='37822' date='Jul 4 2007, 01:01 PM']Thanks for the info,looks like the pump is ok.the main cam cogged tensioner rollers have wear and also the top belt guide roller but the rest are ok including the tensioner damper.

From looking at the balance shaft belt guides it looks as if the belt was run on the slack side.

Before i removed any thing on the cam belt i set the cam pulley mark to the mark on the cover.

The crank pulley did not have any marks so have centre popped some.

Will make note of all the adjuster positions.

Any comments and advise welcomed.



[Image: attachment.php?thumbnail=3611]

Cam pulley and cover marks.

[Image: attachment.php?thumbnail=3612]

Crank pulley and cover centre popped.

[Image: attachment.php?thumbnail=3613]



This was the varrible water leak.

Replaced the o ring and fitted with rubber lube after a good clean up.

Waiting for the parts to arrive before i can do much more.[/quote]



The tdc mark is on the flywheel through a small hole in the bell housing and use a flywheel lock

to keep in place before taking off the timing belt.

Good luck
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#6

Thanks for that,it will be less of a fiddle when the cam belt is being fitted, i will look for it pronto.

Hope the flywheel is not 180% out by the marks i made!
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#7

[quote name='winger' post='37845' date='Jul 4 2007, 10:21 PM']Thanks for that,it will be less of a fiddle when the cam belt is being fitted, i will look for it pronto.

Hope the flywheel is not 180% out by the marks i made![/quote]



Call Jason at paragon for the lock and as long as the mark on the flywheel is centered in the hole

in the bell housing and the mark on the cam pulley line up with the mark above the distributer line

up your good.
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#8

Another way to assure TDC is to take out the #1 spark plug and put a soda straw or similar down through the plug hole. It will rise and fall with the piston to show you TDC.
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#9

i don't think you can install the flywheel 180 out
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94 Midnight Metallic Blue Cab Porsche 968 w/deviating cashmere/black interior and WAY too many mods to list - thanks to eric for creating www.968forums.com



"It isn't nearly as expensive to do it right as it is to do it wrong."
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#10

Flash i'm thinking that if the cam pulley runs ar half crank speed and i may have timed the cam to the marks but half out on the crank.

Is this possible or am i going the wrong way.

Anyway I have checked the flywheel mark and it is dead on the mark with my marks as well. phew!
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#11

Fitted Bilstein and German Ruville tensioner rollers, the top roller cam belt guide have used again,this is just a non tension roller that keeps the belt from flapping about.

I marked the old balance shaft adjusters to see what the positions the new ones were in when fitted.

I have the new set in totally different positions.

Picture enclosed of progress.



   
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#12

From my rough measurements of the width of you old balance belt relative to the width of the sprocket, it looks like you had the exact situation I had - somebody installed the incorrect 14 mm wide balance shaft belt on your car. I believe this belt is for a 944. I suspect that this narrow belt "walks" along the sprockets, rather than being seated proberly against their edges, which generates extra heat, and increases the chances of skipping a tooth. The good news is that it looks like your new belt is the correct 18 mm width, so you should be in good shape going forward.



I urge everybody to drop what you're doing, mosey out the the garage, and take a look at your balance shaft belt. If it doesn't cover the full width of the sprocket, order a new one immediately. If it's close to the interval to replace the timing belt, order it as well. I'm not saying your engine is going to explode if you drive one more mile with the 14 mm belt, but I would plan on replacing it as soon as practical. Maybe I'll post this is a new thread, as I think it is fairly important.
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