Hello,
My youngest son has been looking for a first car. He just found a GREAT non abused Gen. 4 v8 limited /178,000 with repairable frame rot for $900. This truck has been sitting for a year- we put a fresh battery in it and in the first five minutes we fried the serpentine belt. Just replaced it today and 1) it continues to make belt noise/squeal when revving 2) and the belt is getting really hot... to the point where you can smell hot rubber. What should I check/change- idlers, water pump (engine is not overheating/runs smoothly), bad alternator? He's so excited to get this rig on the road- I'm just not familiar with this engine and could use some help figuring this out. Thanks

1sam16

Sounds like the idlers and/or tensioner are toast. Probably a good idea to replace them all. You can get the Gates serpentine belt kit which includes the belt and all pulleys and the tensioner needed. Verify that all the other pulleys turn freely when you do it. Water pump, alternator, AC, power steering.

More Information for GATES 90K38488

Extremewlr,

Ok great! Since we'll have it all apart we might as well replace both the idlers and tensioner. I will check that the alternator and water pump spins freely.

I've owned a 97 (RIP) a 02 4runner and restored a FJ40 up in Alaska. This V8 4runner feels like a different beast. Thanks for your wisdom.

1sam16

Replacing the tensioner is a big job, you can just do the tensioner pulley and save a lot of work/time. My tensioner pulley was seized and I replaced the whole assembly, but pulley was all that was needed. I used the Gates set referenced earlier from RockAuto.

Rdruss,

Perfect timing I was just getting on here to ask that very question. Thank you!

1sam16

On the V8 the water pump is not operated by the serpentine belt, it is operated by the timing belt, so it's not a part of the issue.

As mention it's most likely either the tensioner pulley and or the idler pulley.

Be sure to measure the diameter of these pulleys before buying new ones, you didn't mention what year this V8 T4R is but on my 2004 the tensioner pulley could be one of 2 different sizes, I had to change mine tensioner pulley for the same reasons you are experiencing, around 2004 the pulley size changed, luckily I had measured mine because at NAPA the pulley listed was the wrong size and we looked at a 2005 pulley and it was the correct size, so again even if yours is a later model other than a 2004 just measure the pulleys to insure you get the correct part.

If I remember correctly one pulley was around 3 1/2" the other around 4", both are listed in MM but you can determine what it would be in inches easy enough.

Auseeker-

This forum is awesome- thank you! My sons rig is a 2004 limited with the 4.7. I would like to just replace the tensioning pulley if at all possible... The tensioning mechanism seems to move smoothly, and I'm certainly not getting a lack of tension issue… The belt is melting lol. But I haven't found the part # for the tensioning pulley apart from the whole assembly. Do you have that number? thanks again

1sam16

Yeah, I was running on 4 hours of broken sleep yesterday. Just throwing things out there and for some reason included the water pump

Interesting note on the idler pulley sizes, I had no idea. I just used the Gates kit I linked on my 03 and it all worked out. I'm not sure how much a difference it would make if one pulley was used in place of the other tho, as long as the belt was the correct length still, which the tensioner should account for and still maintain proper tension on the belt.

Before removing either pulley try turning them by hand to see if they're seized or ruff sounding, so you know which or if both needs replacing.

It's been a few years and I went into the local NAPA store to get mine...but I looked the pulley/s up on their website, one is 90mm (3.54") in diameter for earlier V8s the other is 102mm (4.01") in diameter for later V8s....as mentioned measure yours on the vehicle before getting one, also the serpentine belt are different as well depending on which pulley you have, the bigger pulley take a longer belt, the smaller pulley takes a shorter belt.

I would advise that you purchase the pulley locally so if for some reason it doesn't fit you can return it easily.

Link for the 90mm pulley...

Just a moment...

Link for the 102mm pulley...

Just a moment...

It is the tensioner pulleys that can be different on the 2004 V8, I really don't know if the idler pulley size can be different, I haven't changed my idler pulley, the 2003 V8 tensioner pulley will be only one size it's the smaller 90mm (3.54") pulley, the pulleys changed sizes midway through the 2004 model year, I just replaced the pulley on mine and it was the 102mm (4.01") pulley.....I had to go back and get the different size belt because I couldn't the new one I had bought a couple of years earlier to have on hand on, it was too small, apparently whoever change the belt last before I bought the T4R must have got the belt for the smaller pulley and somehow got it on there because I had to cut it to get it off, I couldn't get the tensioner to move enough the slip the belt off, so the belt size would have to be the correct size IMHO, I'm thinking the smaller belt someone installed may have helped shorten the life of the pulley bearing because it was too tight.

Ah, yeah, that makes sense. I guess with the Gates kit, since it comes with everything needed, the pulley sizes are already matched so it doesn't become an issue.

Thanks guys- I went to an auto parts store this morning, just to see what they stocked. The guy I was working with said they had several different options… I'm going to drop that serpentine belt again this afternoon check the idlers/tensioner pulleys to find out which one is the culprit remove it/them and bring it in to make sure that we get the correct replacement. He said he did have a # for a replacement pulley for the tensioner… We will see.

1sam16

Pulled the idler pulley and the tensioner pulley- both need to be replaced. But the real issue is a frozen alternator I found a YouTube video on how to remove/replace. Doesn't look too difficult. Thanks for your help!

The alternator on the V8 is a little more difficult than other Toyotas of the same era, but not difficult. Don't give away the original Denso alternator for a cheap Chinese reman. It's not going to last. Either put a Denso back on there, get the bearing/pulley replaced, or rebuild the original alternator.

I agree with @Unner get a remanufactured Denso alternator!!