4.0 Idler Pulley Replacement OEM vs Gates Reference

Went through a shit show with the pulley upgrade, originally ordered a gates kit however my Idler #2 blew apart on the highway forcing me to go with OEM the night after I ordered the gates kit and needed part asap.
Here's a quick comparison between OEM vs the Gates kit I received. Unfortunately some of the comparisons will be with used oem parts and not new ones as I needed to get the truck back on the road asap.

Vehicle Information:
2008 Tacoma TRD Off Road
143xxx miles
Automatic Trans
Symptoms were squealing/whining from pulleys on the motor. Eventually Idler #1 failed completely

Some people had mentioned that the Idler #1 Pulley would fit on the tensioner - this is the case for the aftermarket pulleys and NOT the OEM Idler #1 as you'll see later in this post.



Part Numbers (OEM):
Tensioner - 16620-31013
Idler #1 - 16603-0P030
Idler #2 - 16604-0P011
Belt - Forgot to write it down

Gates Part Numbers: (ACK070834 was the Gates kit that I purchased)
Tensioner - 38411
Idler #1 - 36174
Idler #2 - 36173
Belt -

$27 K070834 Micro-V Serpentine Drive Belt

K070834

OEM Tensioner / Idler #1 and two Idler #2's: (disregard the red x - one of the gates units was in the photo)


For starters here's the comparison between the OEM Tensioner (with old pulley) and the Gates Tensioner (with gates pulley):


Now for my application I was keeping my OEM Tensioner in the truck and only replacing the idler pulley so here are comparisons between the different pulleys on the OEM tensioner:

OEM Tensioner with OEM Pulley:


Gates Tensioner with Gates Pulley (notice the height difference between the pulley and the tensioner compared to the OEM photo above)


Gates tensioner pulley on OEM Tensioner (Works fine and the Gates left-handed thread bolt works in the OEM tensioner as well - it's just a 13mm bolt instead of a 14mm bolt)


Now for the comparison between the three pulleys on the OEM Tensioner:
Top - OEM Tensioner Pulley - 0.075 inches gap
Middle - Gates Tensioner Pulley - 0.200 inches gap
Bottom - Gates Idler #1 Pulley - 0.200 inches gap

However with that in mind - the pulley on my truck actually rode at about 0.210 inches from the tensioner so technically either the Gates Tensioner pulley and the Gates Idler #1 would work - it would just ride very close to the back of the pulley.




Comparisons between the OEM Idler #1 pulley and the Gates #2 Pulley:
Both pulleys measure in at about 2.75" in diameter. The Gates branded pulley uses a shim to size down the mounting hole to fit the stock hardware (don't mind the OEM bearing it blew apart so it's supposed to be pressed in the and not sticking out like it does)


The difference between the Gates #1 Pulley and the Gates Tensioner pulley seems to me that it's just a matter of bearing type - both would work on the OEM Tensioner however I believe one bearing might be sealed vs another might not be?? Not entirely sure and I forgot to take photos of the part numbers on the pulleys so that will have to wait another day.

Install:
Install was cake after removing the skid plate. I did everything from the underside including routing the belt over the fan which was just some sort of ghetto combination of fan Ferris wheel style loading of the belt to get it around. Took about 45 minutes to do the pulley swap and that is with the left handed bolt on the tensioner giving me a hard time coming out. I had to use the new one from the OEM tensioner I bought as a donor for the reinstall. However other than that it was one of the easiest things I have done on my truck - got rid of 90% of the whine besides my alternator whine.

Belt Routing Thanks to @Sandman614



Hope this helps people out! Feel free to ask questions - I'll do my best to answer if I still have the parts available.

 

@mach1man001

 

thanks for the comparison ! So ???? IF you were to do it over which would you buy ?

 

Honestly I would always run an OEM belt - but that's me and my OCD with belts on previous vehicles. As for the pulleys I don't know what the longevity of the aftermarket units are - however I do know that my truck went 143k on the OEM pulleys and only died because I got a ton of sediment in them from water crossings. I believe that I read somewhere that the Gates ones use bearings that are sealed so I'm thinking they might be a good option to switch to - they seem to fit minus the tensioner which seems to put the belt just a hair in from the edge of the pulley. I don't see this as a problem persay but it is something to consider. I'm not a fan of the size down sleeves for the bearings to fit the oem bolt holes but everywhere else I read they seem to work and the bearings are off the shelf units that can be replaced as well.

I did order a bearing that was said to fit the one from the OEM tensioner - if this fits then I would suggest going with Gates on all the pulleys except the tensioner and just replace the bearing. I'll keep you guys posted on the success with that swap.

Edit - link to the bearing swap thread
https://www.tacomaworld.com/threads...arings-in-the-idler-tensioner-pulleys.480961/

 

I've always been very happy with Gates, I have gates belts and pullies on my 84 goldwing, a gates belt on my 4.0 and gates timing belt on my 3.4.

Gates's is OEM on many a thing and is in my honest opinion the best of the best when it comes to after market stuff. OE may edge out on a few things but I would have every bit of confidence in Gates equipment on my rig if I were you.

Nice write up though! And the sealed Gates bearings are top notch! Def a good upgrade for offroad.

 

Thanks for the heads up Jason

 

Gates makes some good stuff. I used their belt and pulleys when I swapped them out on my Tacoma. I also left the OEM tensioner in place and just swapped the pulley. I put the gates pulley onto the Toyota tensioner arm, no problem. Everything stayed nice and quiet for as long as I owned the truck.

 

Sub..... nice write up Jason.

 

I have been thinking about upgrading my pulleys for some time now. I am running around the same amount of mileage and I am starting to get a lot of creaking and groaning on take off. I am assuming my pulleys or power steering pump is where I need to start. Thanks for the great comparison.

 

After doing all my pulleys I did have some residual whining which was coming from the alternator - unfortunately over the last couple of days it has gotten significantly worse and is now making a ticking sound so I'll be replacing that next week as well... Thankfully these aren't as expensive as Evo ones...

 

So you threw a brand new tensioner in the garbage or tool box and put the new pulley on the old tensioner, I just don't understand why someone would keep a 140,000 mile part on their truck when they have the new part in hand and it would have only taken a couple more minutes to install, being "OCD" it just doesn't compute why you would do that.

As for the gates kit, I installed the whole kit from rockauto a little over a year ago and couldn't be happier.

 

No I still have the new tensioner.. Not sure where you get a couple of more minutes. It's a lot more than a few minutes to pull the tensioner out on the 4.0 and it rarely ever fails. Even the dealership said they have yet to see a tensioner fail.

 

I replaced just the bearing in the tensioner pulley

Oem belt works great

 

Local dealer replace mine this past summer - '15 4.0L PreRunner with about 25K on the motor. It happens.

 

You're the first I heard of it - anything can fail so I guess you got unlucky.

 

I find the pulleys typically fail when you do a lot of deep water crossings and or see significant mud with the truck. I've had 3 die in 141k miles so I have experience in this area. I've only ever gone with OEM pulleys though so I'm not sure of the gates quality. The price of the Gates units is hard to beat though.

One thing I do that I'd urge the rest of you to do is keep your old belt when you replace it. It folds up pretty small and fits behind the seat between the storage bins and the C pillar. Always good to have a spare when out on the road. The belt seems trivial but without it you don't have power steering, electricity, or the ability to COOL the engine. You're pretty well fucked unless you have another one handy. Cheap insurance.

 

Exactly what I did with mine - kept it as a spare just in case...

 

I have the tensioner and idlers all sitting in a box waiting for install. All OEM stuff, but I've had some grinding noises for a while so I'm ready to get them changed.

 

Bumping it up! 20k miles still going strong! Not a hint of noise at all from the belt/pulleys