Hey guys,

Wondering if anyone has replaced their Idlers? RockAuto calls them upper and lower, just wondering if based on the picture I would need 2 upper and 1 lower? Also they call out 2 separate bearings for the tensioner. I changed my Serpentine Belt not long ago and 2 out of the 3 idlers didn't free spin very well and I can hear a slight whining from 1 of them now.

Thanks for the help!

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Yes. 2 number 2’s.
16604-0P011 OEM Idler Pulley 2010-2019

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Some of the 5th gens do not take 16604-0P011 for the two upper idlers, depending on the mark code they may actually take 16604-31030. Ive also been told that the two upper idlers some will take a inner and out plate between the idlers and some only an outer. I’ve gotten no clear answer from Toyota on this despite calling two dealerships.

Looks like you’re right. Crazy.
Here’s a link, look at the 4Rs these fit and the years and models are all over the place.
1660431030 - Accessory Drive Belt Idler Pulley. Becoming, BDrive - Genuine Toyota Part

OP THE TENSIONER PULLEY BOLT IS REVERSE THREADED

I found out the hard way.

1000mph how does one view their mark code? Is it on the pulley itself? If so that would be a challenge getting parts ahead of time as I don’t know how one would view numbers stamped on the pulleys. Sadly if you use the wrong one I am told it will work for awhile but will fail quickly. Would love to see how both are designed and the differences.

Yeah, it’s easy to take pics of the upper #2 idler pulleys and read the marks. Mine are both 013’s.

Maybe I’ll get a pic of the lower sometime soon.

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Don't forget end plates if you ordering OEM Toyota part (each pulley has 2 steel washers/covers sold separately).

My '14 is nearly 100k and I plan to refresh my belt/pullies. Is it just the No. 1 pulley, x2 No. 2 pullies, and the serpentine belt that is commonly replaced? Is the fan, steering, or alternator pulley swapped as well?

I did all idler pulleys, tension pulley, fan clutch and the belt.

Not very camera savvy, how did you get such clear shots of the pulleys to read the mark code? I’d like to do the same to see which ones I should order. Maybe I could try with my phone coming from the top side.

Thank you this is helpful. I’m not seeing part numbers for the inner and outer plates/washers for the LOWER idler pulley. I think both UPPER idler pulleys have an inner plate 16649-310207 and an outer plate 16659-AD010. I haven’t fully confirmed this as I’ve found two dealerships not to helpful in figuring out what all I need to order. In fact one of the dealerships (parts dept) told me I could find my mark code for the pulleys on the sticker found when opening drivers door. Took me some time to figure out he was way off.

I’m assuming, maybe incorrectly, that there is no need to order new pulley bolts. I do know I’ve seen corroded and/or worn pulley plates/washers.

I'm trying to get a list of parts, let me know if this is correct. I got these P/N's from McGeorge Toyota.

2014 4Runner:

No. 1 Idler (Lower) Pulley: 16603-0P030 (No plate covers required)
No. 2 Idler (Top) Pulleys x2: 16604-31030 x2 (My '14's two top pulleys has 7016 mark codes) or 16604-0P011 for vehicles with 7013 mark codes
No. 2 Idler Pulley Outer Cover: 16659-AD010 x2, Inner Cover: 16649-31020 x2
Serpentine Belt: 90916-A2015
Fan Clutch: 16210-0P020
Belt Tensioner Assembly: 16620-31051


I think I may re-use the existing outer/inner idler plates if I can. Also is the replacement of the pulley tensioner mechanism a necessary job?
@Rpede @<<<<

Okay, I edited this post to indicate P/N 16603-0P030 as the lower idler/No. 1 pulley. That P/N does have the "DOUBLE" stamped on the pulley from the images I've seen. Going off @1000MPH post it does appear that the No. 2 idler pulley outer/inner plate covers have a specific mark code but I can only find the plate covers for those with mark code 7013. Curious if these same P/N's work with the 7016 idler pulleys.

I believe the lower idler pulley is actually 16603-0P030 which you list as the tensioner pulley. I may be incorrect as the diagram isn’t the best. The diagram seems to show the tensioner pulley as being linked specifically to the purchase of a new tensioner unit. The pulley tensioner mechanism replacement seems like a far more in depth job so I’m holding off on that one for right now. I’ve heard about more frequent failures with the two upper and single lower idler pulleys so I’m tackling the easier stuff first. I am not seeing an inner or outer plate/washer for the single lower idler pulley in any diagram so maybe only the top two idler pulleys have those?

The fan clutch I plan on replacing when I do the water pump, however I imagine replacing it when you do the idler pulleys also makes sense. If you have time update us on what you are doing as I also have a 2014 and may be heading down the same road.

Lower idler pulley is No1 pulley and uses 2 bearings (says "Double" on pulley) does not need cover plates. Follow parts diagram in FSM and you'll get what you need. Tensioner pulley can not be ordered separately from Toyota (because it uses left tread it gets literally screwed up often thus tensioner assembly sold as unit).