rihaa

I don't believe that the fact that the engine is an interference type has anything to do with making an engineering mistake. Designing an engine of this type is a decision made at the beginning. It is the fact that if the timing is off you can get valves colliding with pistons that is cause for the use of the tensioning tool. It is more of a precautionary measure than anything.

Brian Morris

A couple of posts have said that "Porsche recommends re-checking the auto-tensioner". Where? Is this in a tech bulletin, because it is specifically not in the manual. Actually the manual says "no further checking is necessary".

Yes, many websites, emails, posts ... say this, I'm just wondering if Porsche ever said it.

--Brian Morris
89 951

Brian Morris

A couple of posts have said that "Porsche recommends re-checking the auto-tensioner". Where? Is this in a tech bulletin, because it is specifically not in the manual. Actually the manual says "no further checking is necessary".

Yes, many websites, emails, posts ... say this, I'm just wondering if Porsche ever said it.

--Brian Morris
89 951

Quickbeam

Please correct me if I'm wrong, the only reason this car requires a tensioning tool is because water pump runs off of the timing belt. I'd imagine the water pump bearings are most sensative to the tension. There's the design flaw.

Bill

Well I do not feel the belts are a design flaw.....just a design solution.

You have to realize that aluminum expands at twice the rate of iron. The GM engineers used cast iron blocks and heads which allowed for a timing chain. Minimum expansion, noisy chain, no stretch, HEAVY engine. Porsche chose aluminum, a lot of movement, quiet flexable belts, belt stretch, very light motor.

There are many complex issues that confront the engineers. Before we go bashing them, you have to understand the amount of though/knowledge/politics/love that it takes to transform a lump of metal into our beloved hobby.

I for one, do not think the Porsche engineers do such a bad job. That is why I own one.

Doug944s2

The "auto tensioner" description is a misnomer, since you actually have to remove the timing belt cover, then loosen two bolts, let the spring do its work, and then retighten. (Also, mark on cam pulley needs to be seen in inspection hole to assure #1 piston is at TDC). You'd think, if anything, the tensioner's spring would lose tension, and under-tension the belt, so I give it a little extra push for tautness before I snug everything down.

I've had my mechanic check the belt twice after doing the adjustment myself, and both times it's been spot-on. But, if you need extra peace of mind, buy the trick little tool.

P.S. I believe the S2 timing belt is a little sturdier than the 2.5-liter engine's belt, but I'm still going to stick with a 45,000-mile change interval, and tension it every 15K.