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-   Porsche 924/944/968 Technical Forum (http://forums.pelicanparts.com/porsche-924-944-968-technical-forum/)
-   -   On the subject of 16v timing belts... (http://forums.pelicanparts.com/porsche-924-944-968-technical-forum/166922-subject-16v-timing-belts.html)

109er 06-09-2004 06:38 AM

On the subject of 16v timing belts...
 
Ok, we're all agreed that the t-belt needs to be watched very closely... so is there any reason why no one has developed a "reinforced" belt, with some sort of fibrous internal mesh (or whatever) to lend some added strength to that rubber band? Or is there one out there and I'm just not aware of it (very possible)?

Seems that might be a helpful thing to have for those of us with 16v motors...

Lynn

Texas944 06-09-2004 07:24 AM

They are fiber reinforced. When I did mine, I went and bought Gates belts - I sold them for 3 years and the only time I had one come back was because of mis-use or incorrect applications. Now there agg belts are not the greatest, but we arent using them!

Brando 06-09-2004 01:35 PM

And this is why all 944 owners wish they had a timing chain :(

SoCal Driver 06-09-2004 06:07 PM

He does have a timing chain. Change the belts every 30,000 or less, the chain tensioner pad every 60,000 or less an there usually is no problems with them.

Oh yes, never trust what a PO says about the belts and chain tensioner unless they have absolute proof. Then still change them.

jetmax 06-10-2004 02:04 PM

If only someone made a cam chain set up that replaced the belt, and cams that were connected by sprockets instead of a chain and padtensioner like them there Benzezzzzz.

I even remember the 380sl benz that had a problem with the timing chain stretching so they did a recal for a twin chain conversion.

Things that make you go HMMMMMM!

John
90 944s2 cab
196k miles

StoneGrey 06-11-2004 10:31 AM

Close up of my Belt...... It seems it's Steal fiber re-enforced...... But belt snapping is not the major couse of failure.. its those damn teeth..... based on what I've read... luckily no first hand experience ...



http://forums.pelicanparts.com/uploa...1086975038.jpg

singpilot 06-11-2004 01:04 PM

The Benz' you referred to do have two row chains, and tensioners too. Oil pressure fed ones. They age, and sag, and the chain jumps time, and yes, crash valves. The single row chains were not strong enough to pull the valve train in the V-8's.

The 944 16v engines use the same rubber belts to turn one cam. The other cams are connected to the first cam by chains inside the engine.

Like I said, I really liked the performance numbers and the look of the 3 litre S engine. Then I looked under the cam cover and saw how it all worked. I realized I wasn't going away from the rubber belt cam drive in an interference engine, I was compounding the problem, and walked away from the car.

AaronM 06-11-2004 03:27 PM

The things about timing belts that no-one realises:

They are a cheaper and easier way to add overhead cams to an engine because the engineers to not have to devise an oiling system.

They are quieter than timing chains (in the early 1980's when Porsche developed the original 944/924S/968 engine they were _vastly_ quieter than chains).

They transmit less vibration into the valvetrain than chains and far less than gears.

*****
While people seem to complain about the timing belt on these cars a lot, it's not significantly more expensive to replace the timing belt on my '87 924S than it was to replace the timing belt on my '88 Honda. Yes, the Honda's belt was spec-ed for 60,000 miles instead of 30,000 miles, but the Honda also has a less aggressive cam profile and therefore puts less strain on the belt.

Like anything else, take care of it and you'll be fine. I understand the worry about the belts, but these cars are no worse than any other interferance engine that uses a timing belt.

SoCal Driver 06-11-2004 09:15 PM

The 'S' belt is steel reinforced???

bigyagi 06-13-2004 12:04 PM

s= sock!!!!

MJ & JJ 06-14-2004 11:41 AM

it isn't what the belt is reinforced with. Typically that isn't the problem, the teeth actually shear, get stripped off the belt. I found a car where the PO didn't change the belts and the teeth/cogs where stripped from the belt, the engine stopped quick, Still haven't thken the head off to determine the full extent of the damage.

JJ

SoCal Driver 06-14-2004 01:57 PM

If it's an 8 valve most likely just the exhausts and some of the intakes are bent. Seldom do you see seat and head damage.


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