Pics were taken with my iPhone from the top, use the volume button instead of touchscreen.

Yeah, looks like the ”pulley covers” are distinguished by mark as well.
Here’s the diagram btw...
WATER PUMP. Toyota | Toyota

I took a pic of my tensioner asy awhile back too if you want to see how to lock it back. No pic of the tensioner pulley, unfortunately. It’s in this thread...

Serpentine Belt replacement


I would not get the Toyota belt when you can get quality aftermarket and OEM for $12.

I can’t justify replacing everything that spins as preventative maintenance. I’ve got friends with 300,000-450,000 miles on their Toyota trucks and it seems hit and miss what is gonna go out.

Clearly I need to take an iPhone picture class as I couldn’t get anywhere near the quality of pics you posted...finally got a clear enough one to get my mark code...appreciate your help with this.

Would you recommend as preventative maintenance in changing out water pump, thermostat, and upper/lower hoses? 130k miles no leaks detected.

Was also thinking of adding an inline magnefine trans filter. I do regular changes on 4Runner, have already dropped pan replaced screen filter, cleaned magnets. I’ve had tremendous success with these filters (genuine ones) and prior vehicles. Weakest trans ever 2003 Honday Odyssey dealership mechanic came out of the shop one day and asked how I’ve gotten 400k miles on it without it failing and told him must be magnefine filter and atf drain/fill every year. I don’t see any posts related to 5th gens and magnefine filters must be because these transmissions are reliable or vehicle age newer so less concern?

Also have the lovely needle bearing issue (only 5th Gen part-time 4WD 4runners have to deal with this headache) starting on left front side and may need to tackle that soon. Learning so much in this forum and TRULY appreciate everyone’s wisdom here.

It’s up to you. My coolant hoses look and feel good and my coolant is really clean. Water pump, thermostat will only get replaced if needed. I might not ever replace the trans filter.

I replaced my trans filter in the fall do bad things happen when you replace it? Should I pull the pan again and inspect or look for something? I just replaced the pan gasket and filter and filter o-ring, torqued all back up. I saw so many changing their filters online that I didn’t think to research that it may cause problems. Would you mind sharing your concern with changing filter in tranny? Appreciate all your help and advice.

Nah, I’m sure you’re good.
Small chance of making a bigger problem out of the solution but my aversion to it is it seems like work that isn’t totally necessary to get my truck to 300-400k miles. May change my mind down the road.

Would appreciate your help. Based on the mark number on my top two idler pulleys I take 16604-31030 pulley for the top two or No. 2 idler pulleys.

These pulleys (top two idler pulleys) have changed from past and now require two different pulley plates: “Inner plate” 16649-310207 and “outer plate” 16659-AD010. Two plates were not used on the superceded factory part.

Question: Do the above referenced pulley plates stack on top of one another? In other words both being in between bolt and face of pulley? Or does one go behind the pulley itself and the other on the outside of the pulley??

The diagrams seem to show both types of pulley plates as being in between the bolt and face of pulley. However this makes no sense to me having both plates stacked on top of each other. Can anyone confirm? Wish I could compare old to new but the part changed and now two pulley plates are used for each of the top two idler pulleys. I am getting different answers from different dealerships to make this even more frustrating.

I pulled the top #2 pulley from my 2010 to inspect the bearings today. The pulley is easy to get off, use a 14mm deep socket with a breaker bar on the belt tensioner, and a regular 14mm on the pulley bolt. Threads on the idler bolts are normal rotation, lefty loose-y.
The pulley itself and the cover plates were pretty clean with no rust.
The cover plates look like the same part front and back but the parts catalog lists separate part numbers.
Bearings are not as tight as I would like but they are still very smooth rolling. I cleaned up a little sand and dirt and reinstalled. Torque is 40ft-lbs.

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Thanks for sharing this! Did you decide to replace any or slap on a new belt? When I changed my 3 idlers I was shocked by how much it quieted overall noise at idle. Wasn’t expecting this because the 3 I removed seemed in good shape.

The belt is fine, only 26k on it. I might buy the idlers now since prices keep climbing but I won’t replace until they get worse. I was thinking of some quality aftermarket ones but now I’ll probably stick with OEM.
Looks like I can get the #2 for $50 ea and the #1 for $60

Has anyone pressed the old bearing out of the pulley and install a new one?
Amazon.com: New Koyo Idler Pulley Bearing 6302RMX for Toyota/Lexus Same Day Shipping 6302 RMX : Automotive

I've always pressed in a new bearing. I'm also curious ... I'll pull out a seal to inspect the balls and races on the old bearing.

Looks like I’m not going to be able to press the old one out without destroying it.

Lexus and Toyota tensioner pulley bearing replacement - YouTube demonstrates how to replace the bearing. Yes, the old bearings would be damaged when pressed out.

I ended up buying the OEM idlers using today’s 20% off Toyota sale.
Hard to pass up.
166030P030 $ 46.71 Accessory Drive Belt Idler Pulley
166040P011 $ 41.16 Accessory Drive Belt Idler Pulley

Edit: arrived today.

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