skshepherd

Had a tapping/knocking sound develop on the front of my engine, kind of sounded like the piston slap in the 2.7's. After much investigation my mechanic discovered that it was the crankshaft pulley! It was coming loose! The last place I had taken the truck to to have the Timing belt done had not torqued the crankshaft pulley down all the way to the proper spec. There is a link somewhere on this forum to an article specifically adressing this but usually what happens is the thing can fly off or twist on the key hole and be out of sync. There was no mention of the noise I had though. I thought it might be a bad tensioner or pulley # 2 but it was the pulley wobling around. Even tightening of the drive belts initially quieted it down but it reoccured and let to further investigation and the finding of the loose pulley itself. Anyhow the incompetence of the first job led to many hours of labor to discover what was up and I could have paid for another timing belt job.

Just hope this helps someone in the future.

So if you have a knocking or tapping sound from the front of the 3.4 engine, and it gets worse the warmer the truck gets, double check to make sure your crankshaft pulley is not loose!

Good luck.

mt_goat

Yeah this is getting to be a common problem, made worse by the fact that many sources have the wrong (old) torque spec. The correct (new) torque spec for the 5VZFE is 217 ft-lbs. Its a good idea to use loctite on it too. Of course then there is always the shops that don't even use a torque wrench and have little idea if the bolt torque is to spec or not and really don't care as long as you are at least 100 miles down the road when it comes off.

mjwalfredo

Interesting. I suffered the undertorqued crankshaft pulley bolt as well. Well in my case, the tech may not have slotted the key correctly but anyway, I found the pully would loosen up so much that all the belts popped off. You'd definitely notice the loose bolt when power steering goes and all the dash indicators come on

Adam F

Aren't you supposed to replace the crank bolt on the 3.4L too?

Jerm

I to had this problem, and the shop that did the work replaced the bolt, pulley, the plastic cover, belts and did the work for free. They told me to come back in a thousand miles so they could re torque the bolt if needed. At least the pulley hadn't fallen off yet other wise it could have been real bad.

Bigblock

I should get my lazy arse out there and check mine!

Amir904

im getting a very similar sound, in fact it started not too loud, now its loud as heck. i had the timing belt done by the toyota dealer, would they take responsibility easily?