Timing Chain Tensioners

[maytag]

Hey there! Good luck today.
I can't answer #1, but I can answer #2 for you.

When the manual talks about "TDC", it's not talking about tdc for a specific side, it's talking about a very specific position. Think of it as "service-mode". And while one cylinder is indeed at TDC (iirc, it's cylinder #2 for this motor?) that's not really important. What matters is that you're placing the motor into a known, unchanging position, so that if, during the course of a given procedure, things move, they can be easily put back where they belong. This is especially crucial for procedures that affect timing. SO: when you lock the motor at TDC, there's a mechanical lock (pin) that keeps the crank from moving, and then there are additional Porsche tools available (though some of us have made our own) which lock each cam in their correct location relative to the crank.

Did I explain that in a way which makes sense to ya? I can't always tell..... haha

[Seal1968]

There's a lot of guys that lock it at TDC with a pin or drill bit (5/8?) and proceed without the cams locked changing ONE tensioner at a time.

Doing without the cams locked has the small chance that a bit of tension released when removing the tensioner may slightly adjust the camshaft position in a worst case scenario.

I suspect this would be more of a risk with a high mileage engine where the chain is older and stretched and the guides have wear.

Certainly others will comment and either support a simple TDC lock, or the full-on lockdown recommended by Porsche...get ready lol.

FYI...If anyone tells you timing chains don't stretch, they are full of ****************.

Good luck.