Thread: timing question (tdc)

I've been dealing with a plaguing issue and finally got around to doing a compression test but when the piston in the #1 cylinder is at the top of its travel the crank pulley is a little bit before the first mark on the pulley. Should be at the second mark in from the left on the pulley. I'm wondering what would/may cause this to not line up properly.

So in my head regardless of cam timing the crank marks should always line up with the position of the piston? So if the piston is at the top of its travel the crank should be on the tdc mark?

The only thing i can think of is maybe my crank pulley has started to seperate?

Does anyone else have any ideas on why the crank tdc timing mark isnt matching up with tdc of the piston? Any help is appreciated. Thanks

I would agree. Regardless of cam timing (the chain), the pulley is keyed to the crank, so the pulley should always read correctly with what the pistons are doing.

I had a pulley separate, so I'd be inclined to suspect that as well.

Yep sounds like the pulley has slipped

Sounds like a torn crankshaft pulley to me.

Thanks for the replys guys. I'll be heading back to work on the car tomorrow. Got a couple spare motors so gonna pull the crank off to have a look and probably end up swapping one over for the time being.

What i like to do on any oem crank pulley that has rubber in it is to make a white paint line from outer portion to inner portion to provide a quick visual inspection if the outer portion of the pulley has slipped.

You can even do this on an old suspect pulley. A bad pulley will show mismatched paint oem line after driving for a few hours or in few minutes if it is completely ripped.

Smart tip

And a bad pulley will also eventually separate while your driving down the road- usually when you're @ WOT. It happened to me in my 97 SE-R. Saw the outer ring bouncing down the highway behind me

Actually not.

Most of the time the stress of the AC compressor engaging will wear the rubber bonded pulley out and tear it. We see this issue alot with grandma-driven G20, Maxima, Altimas, and Sentra. As soon as the compressor kicks on the pulley starts to squeak or squeal and sometimes the pulley will start to wobble when AC compressor is engaged.

It happened to me man. My 97 SE-R with no A/C. Went to 7000RPM heard some noise under the hood and saw the outer ring rolling down the road. I even made a thread about it on here - probably around May 2012. the car had 180k miles or so. I used the issue as an excuse to get a UR pulley set.