Replacing Serpentine Belt Tensioner (not just bearing) (1 Viewer)

[ColoradoNick]

Hey Team,

So I'm a bit stuck. I wanted to replace the serpentine belt/idler pulley/belt tensioner, generally speaking it was all easy stuff until I got to the tensioner. It looks like it's held on by a 12mm (I think) bolt and a hex bolt. The hex, I am scared to really wrench on. It didn't budge easily and I thought.. I wonder if this is a left hand thread like the bolt... which would make sense. I also wanted to make sure I had a tight fit with my hex key to not strip this.

The questions being:

1. Can someone confirm if it's left hand threaded?
2. Can someone confirm the size of the hex?
3. Assuming we can't tighten this a specific spec (ft lbs)?

Here is the video showing what I believe to be the last fastener holding it in.

Here is a picture of the new tensioner showing the hole this fastener sits.

 

[TeCKis300]

I can't confirm as it's been so long since I've done mine. The repair manual does not state that it is reverse thread.

6mm hex. 17 ft. lbs

 

[doru]

Just replace my radiator w/ all the other stuff and that is not left threaded.

What is left threaded is the bolt holding the pulley to the tensioner - 14mm standard head. This is so when you apply the wrench on that bolt to release the tension on the belt it doesn't unthread.

The Allen is 6mm, the other holding bolt is standard head 12mm. These are the only two bolts holding the tensioner. Both are to be torqued to 23Nm/17ft.lb. You should be able to easily tighten those back to specs.
Use a full Allen socket to get it out (not the beveled ones).

Use a 4 or 5mm (no need to be precise) pin/bolt/screw/screwdriver/etc. to hold the tensioner retracted while you install the belt. Let us know if you do not know what I'm talking about and we can provide details.

 

[ColoradoNick]

Use a 4 or 5mm (no need to be precise) pin/bolt/screw/screwdriver/etc. to hold the tensioner retracted while you install the belt. Let us know if you do not know what I'm talking about and we can provide details.

I think I follow this... though feel free to share more should I realize later I do not in fact understand this and need to write back in 2 hours lol.

I figured out what you meant!

 

[ColoradoNick]

I can't confirm as it's been so long since I've done mine. The repair manual does not state that it is reverse thread.

6mm hex. 17 ft. lbs

View attachment 3377408

THANK YOU!

 

[ColoradoNick]

Just replace my radiator w/ all the other stuff and that is not left threaded.

What is left threaded is the bolt holding the pulley to the tensioner - 14mm standard head. This is so when you apply the wrench on that bolt to release the tension on the belt it doesn't unthread.

The Allen is 6mm, the other holding bolt is standard head 12mm. These are the only two bolts holding the tensioner. Both are to be torqued to 23Nm/17ft.lb. You should be able to easily tighten those back to specs.
Use a full Allen socket to get it out (not the beveled ones).

Use a 4 or 5mm (no need to be precise) pin/bolt/screw/screwdriver/etc. to hold the tensioner retracted while you install the belt. Let us know if you do not know what I'm talking about and we can provide details.

and Thank you!

 

[ColoradoNick]

Just got it off without stripping it! Today is a good day.

 

[bloc]

Also, get a pick in there and clean out the 6mm hex before putting any real torque on it. Dirt tends to build up in there so the bit can’t get to full depth, and this is what usually strips out the head.

 

[ColoradoNick]

Well one more item. The new tensioner spring is tough. I can’t see to get the belt over it, I can’t even torque it enough to get the hex key in there to hold it “open”. Im not a weak fella so I’m giving it pretty good. Worried I’m doing something wrong since I’m applying so much pressure (Redacted after edit)

I found a way with another set of hands. I am amazed at the amount of tension the tensioner applies (go figure). Uploading a photo to show how tensioned it is and make sure it looks good to the crew here.

As you can see here the rotating section is pretty close to the "stop" that is located on the tensioner... that look good? You can tell I do this a lot.

 

[doru]

The way to do the belt is to first lock the tensioner in retracted position. After you install the tensioner on the engine, first you retract it using a wrench on the pulley nut as I mentioned above. You want to have the hook aligned with the hole in the tensioner. Here is your picture with annotations

While the tensioner is retracted insert a pin/etc in the hole in the tensioner, sticking out. That will block the hook from moving past the pin and thus prevent the tensioner extension.

Once that is done you can leisurely do whatever you need to do to easily lay in the belt and check it is properly seated, especially at the bottom around the crankshaft pulley.

When ready to tension, just put the wrench back on the pulley, retract, remove pin, release tensioner.

 

[doru]

AFAIK see from your pictures the belt looks good.

 

[ColoradoNick]

The way to do the belt is to first lock the tensioner in retracted position. After you install the tensioner on the engine, first you retract it using a wrench on the pulley nut as I mentioned above. You want to have the hook aligned with the hole in the tensioner. Here is your picture with annotations
View attachment 3377854

While the tensioner is retracted insert a pin/etc in the hole in the tensioner, sticking out. That will block the hook from moving past the pin and thus prevent the tensioner extension.

Once that is done you can leisurely do whatever you need to do to easily lay in the belt and check it is properly seated, especially at the bottom around the crankshaft pulley.

When ready to tension, just put the wrench back on the pulley, retract, remove pin, release tensioner.

I tried to give that a go but could barely get it back far enough to slide that a 'pin'. I think the spring was just tough but maybe I need to hit the gym.

 

[ColoradoNick]

AFAIK see from your pictures the belt looks good.

Thanks doru. I might be buying a 100 series next week so I am getting my comfort level up for what I am sure will be plenty of wrenching lol.

 

[doru]

I think the spring was just tough but maybe I need to hit the gym.

Spring is tough. Next time get a breaker bar or a ratchet and a pipe. I used a 20" bar.

 

[ColoradoNick]

Spring is tough. Next time get a breaker bar or a ratchet and a pipe. I used a 20" bar.

This makes me feel better

 

[bloc]

Also if you aren’t attacking it from the bottom it is much easier that way. I also remove the center “rib” for the front splash guards which gives much more room to swing the breaker bar/ratchet around.

 

[sleepycruiser]

Sounds like I have the squeaks from one of these. I haven’t been able to find any videos to change out the belt tensioner and idler pulley. Anyone have a video or the FSM pages, etc?

Edit: Actually found some on the Tundra.

Should I replace the entire belt tensioner set or just the pulley?

 

[bloc]

Sounds like I have the squeaks from one of these. I haven’t been able to find any videos to change out the belt tensioner and idler pulley. Anyone have a video or the FSM pages, etc?

Edit: Actually found some on the Tundra.

Should I replace the entire belt tensioner set or just the pulley?

Whole tensioner. The spring inside loses tension over time allowing belt slip and squeal.

Also note that unlike the tundra we have some splash guards under the engine. Remove the two metal side panels and the center “rib” and you’ll have a lot of room to get at the tensioner, even using the hold-back pin which will make sense when you get your new part.

Doing them from the top is possible but much harder.

 

[unclemat]

I replaced the belt, idler and tensioner last week at 113k miles in my 2015. I started getting some random belt squeal. The hex socket bolt in the tensioner gave me a scary moment. The bolt rusts if you drive where the white powder of death is used - my truck is "rust free" and rustproofed up to the wazoo, but you can't protect everything like fasteners on the engine.

I used a good 6mm Snap-on hex bit but was close to rounding the bolt off. Hammering well into the bolt socket, big breaker bar and a "prayer" worked. I read some people had luck with T40 Torx bit. Indeed Torx can be a good trick as it can bite into damaged socket hex.

Really stupid design on Toyota's part, seriously. Wish they used a bolt with an 8mm hex socket or even better a Torx.

I replaced the bolt with a stainless steel one from McMasterCarr - the stock bolts is M8x1.25x47mm so an odd size, but a 45mm bolt was long enough. Torqued to the manual recommended 17 ftlbs. Per my measurements 50mm long bolt would bottom out.

 

[bloc]

I replaced the belt, idler and tensioner last week at 113k miles in my 2015. I started getting some random belt squeal. The hex socket bolt in the tensioner gave me a scary moment. The bolt rusts if you drive where the white powder of death is used - my truck is "rust free" and rustproofed up to the wazoo, but you can't protect everything like fasteners on the engine.

I used a good 6mm Snap-on hex bit but was close to rounding the bolt off. Hammering well into the bolt socket, big breaker bar and a "prayer" worked. I read some people had luck with T40 Torx bit. Indeed Torx can be a good trick as it can bite into damaged socket hex.

Really stupid design on Toyota's part, seriously. Wish they used a bolt with an 8mm hex socket or even better a Torx.

I replaced the bolt with a stainless steel one from McMasterCarr - the stock bolts is M8x1.25x47mm so an odd size, but a 45mm bolt was long enough. Torqued to the manual recommended 17 ftlbs. Per my measurements 50mm long bolt would bottom out.

If you didn't already do this, usually there is crud embedded into the hex head of that bolt. It is wise to use a pick to clean that stuff out.

Also I'm not sure stainless was the right move here.. galvanic corrosion can be an issue between it and some alloys of aluminum. Did you use anti-seize?