1998 S70 GLT Crankshaft Pully Play----Beware?

dcovey · Post by **dcovey** » 31 Aug 2007, 20:04

While accelerating up an onramp three weeks ago my S70 died at about 6000RPM.

I convinced the wife to let me do a total mechanical rebuild, and I'm well into the cleaning and parts ordering, but I discovered something that I thought I'd share.

Turns out I lost the crankshaft pully nut. I have no one to blame but myself since I changed the timing belt 20K ago. The result of losing the nut was throwing the harmonic dampener and the crankshaft gear, which turns the timing belt, so I ended up with 6 bend intake valves.

Of course by the time I discovered the damage was really only 6 valves I'd decided to keep the car an ordered just about every part required for a major overhall.

Now the thing I found that I'd like to share. When I cleaned the crankshaft pully assembly with the dampener attached, I put it back on the crankshaft prior to removing the crankshaft from the block. The pully assembly had at least 2 degrees of play, which means that every time the engine decelerated rapidly, it put counter clockwise torque on the pully nut. I think this play in the crankshaft pully contributed to the loosening of the crankshaft nut and the eventual catastrophic timing failure.

Be interested to hear what others think about this explaination. If you don't agree with my assesment, I won't share your posts with my wife.

Post by **MadeInJapan** » 01 Sep 2007, 01:02

First time I've heard such a thing but it does make sense. I suppose you tightened the nut to specs?

dcovey · Post by **dcovey** » 01 Sep 2007, 12:23

I got close to 130 foot pounds, my torque wrench doesn't actually go that high so I pulled on the cheater bar after it clicked.

I just don't think there should be play in that type of part.

phly50 · Post by **phly50** » 01 Sep 2007, 14:34

Sorry to hear about your problem, and I hope you don't think I am being a PITA but for others reading about this that have yet to tackle a timing belt change - one doesn't need to remove the crankshaft pulley to change the timing belt. Regards, Phil

dcovey · Post by **dcovey** » 01 Sep 2007, 16:03

Very true, bay13 recommends removing the plate underneath the crankshaft pully.

Wish I'd read that first.