[jakeru]

Originally Posted by Nine8Six

You may have found the cause of the IMS failure, yay man!

That was quite a bit of unwanted vibration, geez :/ Good thing you got that done.

Indeed, it was really horrible! Now that I'm driving on a true-running serpentine belt setup, it seems like such smoother feeling reduced engine vibrations. Where before it kind of "hurt" to press down on the gas pedal, now it just feels good. Also, the engine just sounds better - that exhaust note sounds more "pure", and generally sounds good, although that might not make sense. As these are subjective observations, it's possible they can be discounted. But I'm really happy to have to his fixed! (And yes, even with the metallic rattle noise still going on, but perhaps that's another topic.)

Originally Posted by Nine8Six

No hope for that part though, seems formed then stamped. Meaning not a single pulley is the same. Lucky if you can find one that is concentric to the shaft loll. Slight offset on such thin material will wack out the shape of that part in less than 10k miles at revs... wouldn't surprised anyway.

I value your insights about manufacturing process, and am fascinated how uneven these parts were made! The uneven thickness and waviness of the outer faces was perplexing to me. At first I was wondering if they were ground that way for balancing (instead of drilling holes.). But the surface finish didn't really look ground. Your suggestion it's an artifact of an imperfect manufacturing process seems like a more plausible explanation.

It makes me wonder if one of these pulleys, brand new, were tested for balance, how far off would it be? And if they are out of balance, would the crankshaft be balanced together with this part as a unit?

The piece is extremely lightweight, however, so maybe even if the material is uneven, the amount of imbalance isn't going to be significant. If it can't support it's own weight and bends out of shape further in just normal operation, well then after the pulley "auto-bends" in normal service, the imbalance could become a much bigger problem!

Then again, I can't say for certain it wasn't just a careless previous mechanic who pried on this part when, let's say, trying to remove an alternator. I actually found a big pry tool lodged below this area after I picked the car up... no kidding. It's a nice tool also, snap-on type pro quality. A good addition to my tool box!

Originally Posted by Nine8Six

If you are concerned about the shaft runout (TIR) just get an harbor freight mag base and a cheap dial indicator, no need for Japanese metrology there. My guess is if the shaft would be in such a bad shape it wouldn't sound like metallic rattling but more or less like metal crunching. Could be wrong

I do have a magnetic base and dial indicator, but find very few flat magnetic surfaces on which to mount it, plus the quarters are very tight/cramped to do it with the engine in the car.

I did, however, place both pulleys on a flat surface plate and use a set of feeler gauges to measure surface waviness. Neither face of either pulley had even close a straight (planar) face! Depending which pulley (new vs old), which face (front vs back), and which direction I "rocked" the pulley on the surface plate before getting the measurements, I got surprisingly high waviness measurements:
Old pulley: .018", .012" (back face); .010", .022" (front face)
New pulley: .008", .010" (back face); .012", .018" (front face)

At least the new pulley is a little less wavy than the old, but nowhere near close to being flat. What I'm pleased by is at the least the belt now seems to run perfectly true on the new pulley.

Originally Posted by Nine8Six

Some late advice I guess; I wouldn't use a hex wrench as locking tool, as per one of your video. You need the special tool for that part indeed, the rod shape one that fit snug in the pilot hole. Anything slightly unfit for this hole "could" bend the pulley easily when manual/uneven pressure is added to it (I mean look at this poor pulley)

You make a good point, Fred. I used an Allen wrench to pin the pulley against rotation, and unlike they guy in the video who said he used a 6mm, I found a 7mm fit much better and seemed nice and snug. However, you are totally right, and using round profile pin would be even better. i suppose I could have thought to use one of my drill bit of the proper diameter - I have a rather complete set and am sure a I have many options to pick from in this size. You were too late in telling me this - lol!

The pulley actually wasn't under as much torque as I was expecting it to be, especially after watching that video and hearing the guy talk so much about the massive torque wrench he ordered to get the job done. Maybe only ~100 ft-lbs after the 3x ft-lbs + 90 degree turn? Threads were very clean. It didn't feel like the bolt yielded at all.

Originally Posted by Gelbster

Try a straightedge across the face of adjacent pullies -as many as you can span."

With the front face of these crank pulleys being as wavy as they are, and not really having anything to do with the surfaces that belt rides on, you'd get different/inconsistent readings. (At least if you used the crank pulley's face to guide the straightedge - other pulleys might work!)

Originally Posted by Gelbster

I was surprised that the A/C pulley was significantly out of line with the rest of the pullies. This tended to put a lot of distorting force on the adjacent pullies.

Thanks for suggestion, that's a good thought.

It seems my serpentine belt is now running totally straight and smooth. Well, the pulleys may be misaligned a small amount, but at least there is no more belt vibration, like there was before! Before, the tensioner pulley would get "excited" right at about 3000 rpm.

I may do some more tests and capture an "after" video when I have more time to probe around before that access panel.

Originally Posted by Gelbster

If you replaced just the bearings in any pulley - you may not have seated the bearing fully or you cracked it on the press. Better to use a new combo pulley+bearing in my limited experience.

I think I read this comment in some other thread, which prepared me for these pulleys putting up a fight. And while they did indeed put up a fight, I'm quite confident the repair was good one, and it saved me hundreds of dollars over replacing the complete pulleys.

It's hard to imagine the malleable sheetmetal these pulleys were stamped out of cracking if over-stressed. Bending, I think, would be the more likely failure mode if supporting the pulley well enough, or pressing in a "cocked" bearing.

On pressing the new bearing in, I also don't think it's critical how deeply they are pressed. The pulleys have flat cylindrical surfaces where the belt rides, and no grooves, so they don't axially guide the belt.

I took some pictures of how I replaced the idler and tensioner pulley bearings, so especially if there is interest, I could make a DIY thread about it.