Fan belt change issues

[DirtScaresMe]

as i have just purchased the vehicle and the previous owner didnt to regular maintenance to it i need to get it cleaned up for an inspection. oem belts will be purchased soon, but i only had this passed weekend to do under the hood stuff so i had to go with in stock items. just as ill be purchasing a used tire to get it inspected. i didnt realize the inspection was going to be due right after purchase, as every other vehicle ive bought has had a year to go. the a/c belt i have is in good shape, but a cog belt. the new one i purchased didnt want to fit even with the tentioner pulley out of the equation all together. i put the other one back on until i buy toyota parts. im glad im not the only one thats had issues with this, as i was really doubting the past 20ish years of working on cars. lol

My non-oem when I bought it had a cogged belt for the AC and way-overtension and routed-wrong non-oem for the fan belts. I think the fan belts they put on previously were too long so they wrapped them on the inside (wrong way) of the idle pulley.

Sticking with OEM just makes everything simpler and when the truck's ripped open and the sun is dipping low I'm very interested in simple.

 

[ZackR]

On mine the previous belts were run over the top side of the idler pulley so I did the same. It appears this is incorrect and why it was such a pain to install. So far I've put about 1000 miles on the new belts without any issues or noise.

Just found this in the 1994 FSM (should have looked here first before the install to save myself some grief). Totally assumed the way I had it was correct.

 

[DirtScaresMe]

Get a laugh out of my thread from a few weeks ago, deja vu Rth - cant get alternator belts on

 

[flintknapper]

As previously stated....it is an easy mistake to make (incorrectly route the belts, or attempt to).

IF the 'correct' positioning was not noted when removing the old belts or no belts were present when starting the install, (see borrowed picture below):

^^^^^^ Then...one might intuitively think the larger 'flat' of the V-Belts would ride against the tensioner pulley.

If you look at the tensioner pulley for the A/C compressor it is a 'V' shaped pulley and 'requires' the 'V' portion of the belt to ride in that groove (as it does at the A/C compressor and Crank Pulley).

Now...lets go to the fan belts (also V-Belts). As we might expect...they too ride in the V-Groove of the Crank Pulley, Alternator Pulley and Fan Pulley. BUT...the tensioner for these two belts is a FLAT pulley (not V-Grooved) like the one for the A/C compressor.

Conventional logic would dictate the larger 'flat' on the V-Belt would ride against the flat surface of this pulley, right? Wrong!

This is exactly the reason why so many people are 'tripped up' by the belt routing and why that mistake is so understandable.

The reason(s) for Toyota using a flat pulley and placing it where they did, I don't know...but will hazard some guesses:

1. A bolt type tensioner was provided in the first place to provide a more accurate way to adjust the belt tension (spec) than is possible by levering over the alternator, (holding it in place and capturing it). Just Toyota going that extra mile.

2. Flat pulley chosen to minimize friction, noise and wear on the belts, V-Pulley not necessary in this location as the belts are already adequately captured and guided. Pulley is up high on engine....so the belts are not subject to becoming dislodged by debris as the one on the A/C tensioner might be if it had a flat pulley.

3. Routing of the belts....results in the least amount of deflection. With V-belts...the less you change their 'direction', the less you have vibration, friction/heat and wear (read longer belt life, increased reliability).

Now...I don't know if Toyota did what they did for ANY of the reasons I've suggested above, but they did it with 'purpose' in mind, you may be sure of that.

It's just that sometimes Toyota's engineering ideas and purposes are not readily apparent to the consumer (including me).

 

[midfat]

As previously stated....it is an easy mistake to make (incorrectly route the belts, or attempt to).

IF the 'correct' positioning was not noted when removing the old belts or no belts were present when starting the install, (see borrowed picture below):

^^^^^^ Then...one might intuitively think the larger 'flat' of the V-Belts would ride against the tensioner pulley.

If you look at the tensioner pulley for the A/C compressor it is a 'V' shaped pulley and 'requires' the 'V' portion of the belt to ride in that groove (as it does at the A/C compressor and Crank Pulley).

Now...lets go to the fan belts (also V-Belts). As we might expect...they too ride in the V-Groove of the Crank Pulley, Alternator Pulley and Fan Pulley. BUT...the tensioner for these two belts is a FLAT pulley (not V-Grooved) like the one for the A/C compressor.

Conventional logic would dictate the larger 'flat' on the V-Belt would ride against the flat surface of this pulley, right? Wrong!

This is exactly the reason why so many people are 'tripped up' by the belt routing and why that mistake is so understandable.

The reason(s) for Toyota using a flat pulley and placing it where they did, I don't know...but will hazard some guesses:

1. A bolt type tensioner was provided in the first place to provide a more accurate way to adjust the belt tension (spec) than is possible by levering over the alternator, (holding it in place and capturing it). Just Toyota going that extra mile.

2. Flat pulley chosen to minimize friction, noise and wear on the belts, V-Pulley not necessary in this location as the belts are already adequately captured and guided. Pulley is up high on engine....so the belts are not subject to becoming dislodged by debris as the one on the A/C tensioner might be if it had a flat pulley.

3. Routing of the belts....results in the least amount of deflection. With V-belts...the less you change their 'direction', the less you have vibration, friction/heat and wear (read longer belt life, increased reliability).

Now...I don't know if Toyota did what they did for ANY of the reasons I've suggested above, but they did it with 'purpose' in mind, you may be sure of that.

It's just that sometimes Toyota's engineering ideas and purposes are not readily apparent to the consumer (including me).

My guess is that the flat tensioner is an insurance policy of "last resort" against alternator and cooling system failure. Clearly, the tension from the alternator is sufficient to set the belts. But, I theorize that as the belts eventually stretch and glaze, the tensioner becomes increasing vital in preventing the inevitable slack following the drive-force from the crank. That slack would manifest itself first against the alternator, then the water pump. As with two drive belts, it seems mostly be protection against the zombie apocalypse. Just my worthless, uneducated, purely pulled out of my arse, opinion.

 

[baldilocks]

All problems note in this thread could have been avoided by first referring to to FSM. Even something as simple as belt replacement can cause us head aches when we are dealing with a new machine for the first time.

 

[ZackR]

Update: After a month of driving and 2000 miles I decided to swap out the belts I installed incorrectly (over the idler pulley). The new OEM belts went in easily, probably a 10 minute job start to finish if you cut the old belts off. As others have mentioned they slip right on with no tension or prying.

I'm not sure if I wrecked the old belts trying to pry them on over the idler pulley (probably) but they were in near failure condition upon removal. This kind of damage is hard to see unless you slowly crank the engine over by hand looking for it and I was surprised it happened in such a short amount of time. If you have the belts on incorrectly I'd highly recommend getting things sorted out sooner than later.