Nomis

I read up on a thread by VSsc400 and decided to tackle the job myself.
The replacement tensioner is made by Dayco; Part# 89255. The unit comes complete with the tensioner and the pulley and ran me $56.88 at Advance auto parts. The unit is built out of aluminum just like the original.

Here's a rundown:

-Disconnect Positive battery lead
-Remove serpentine belt by using a 14mm socket on the tensioner and turning counter-clockwise.
-Remove the intake filter housing, and intake tubing
-Remove the center plasitc plug cover
-Remove the pax side valve cover plastic and remove the bolts that hold the upper timing cover - you don't have to completely remove the cover, just get it loose.
-Remove the bolts for the pax side coil - no need to remove it.
-There are 2 nuts and 2 bolts that hold the tensioner in. One of them goes through the alternator and tensioner.
-Unbolt the alternator and let it rest on the hoses below it - no need to disconnect the electrical connections.
-Once the 4 nuts/bolts holding the tensioner in are out, you should be able to slide the tensioner assembly out under the timing cover.

Everything went back together easily except for the timing cover around the cap and rotor. For some reason it just would not line up completely. Once I got the upper valve/distributor cover on, you barely notice it. This is primarily a dust cover, so I'm not too concerned with the 1/4 ince gap.

After the replacement was in, I no longer have the annoying squeaking/squealing that I had before. Now it is extremely quiet when idling - as a Lexus should be.

I believe I covered everything. If anyone has any questions let me know.

PERRYinLA

At what mileage did your tensioner quit? I'm at 90K and beginning to get occasional squeeks at idle, too.

Nice to know there is a fix but too bad the squeeky bearing can't just be lubed and possibly save us the trouble of replacing it.

Nomis

I bought the SC about 2 months ago and have been replacing parts here and there to bring it back to it's new car ride/performance. The vehicle had 106K on the clock when I bought it and came with the squeak at the time of the purchase. I had initially thought it was the bearing as well, and so I replaced the tensioner pulley and bearing first - (I can get you the Dayco p/n if you need it). Replacing the pulley did alleviate some of the noise, but it still squeaked when the a/c was engaged. It was the up and down action of the tensioner spring itself that was squeaking. I'm happy to say that once I replaced the entire tensioner itself, it is absolutely 100% squeak free at any rpm, with or without the a/c running. My suggestion would be to try replacing just the pulley and bearing; if that doesn't work then you're looking at a new tensioner.

Nomis

The bearings are sealed units. Once they begin to squeak, they are unserviceable and must be replaced. Unless you wanted to remove the unit repack the bearing with grease and put new seals in. Although the bearing itself is under 5 bucks so it wouldn't be worth it.

There is also another idler pulley just below the water outlet, make sure you check this one out as well. Mine was fine though.

VSsc400

iTrader: (1)

Nomis. good to hear things worked out. Can you believe Dayco makes one for our cars? lol It took me a while to find the part number from dayco but it's a good fit. One from lexus would have cost in the $200 range.

Awesome to hear that you were able to do it on your own, I chickened out and took it to a mechanic but if it does quit on me again i will be doing it on my own since i've seen how it gets replaced.

Just happy to see that things that i posted actually helped.

siniquezu

Is the SC3 and SC4 tensioner the same size/dimensions?

Nomis

I just checked Dayco's website and didn't see a listing for a p/n for the SC300, so based on that I'm assuming they're different.

EUROJulian

How much Lexus part cost? Anybody checked?

Als how the piece looks? It is well made compared to the OEM part?

Nomis

Based on a previous e-mail I found when searching the forums I believe the part was between $120.00 from Carson Toyota and up to $200 from local dealers. The Dayco part is virtually identical, and has a few minute differences that could actually be design improvements for all I know. Either way, you can't go wrong with the part at litterally 25% of the cost of the factory part. Normally, I would be a strong proponent of using factory parts for things such as plug wires, starters, alternators, etc.; but in this case the aftermarket part works fine. Oh, the old one hasToyota stamped on the front, and the Dayco unit does not.

GliTCH

im replacing my tensioner right now. i managed to get the old one out after trying at the upper timing cover for a while and not being able to figure out why it wouldnt budge enough after i got all the bolts out. one of the bolts was seriously hard to see or feel for.

the pulley wheel on the new tensioner is a smaller diameter... what kind of effect will that have? either way, it is the right part number. dayco 89255 so if it worked for you it should work for me. this is really a milestone in my pursuit of learning mechanics, i have never even had to change my own spark plugs yet (although i had a pretty good idea how). im really excited about getting this back together and working again. i should have made a diagram with all the right screws and their locations but i was dumb and relied on remembering, wonder how much of a pain that's gonna be

anyways, its late but im gonna go try to put my ride back together. wish me luck!

GliTCH

alright, i put everything back together and just like nomis said the timing cover didnt fit just so.. but anyway, i started the car up and discovered the MAF wasnt plugged in so i plugged it in and the check engine light went away. started it up, it ran for a while and then turned off. sounded normal while it was running... i waited about a minute and tried again.. the car just whirls on startup i dont hear it crank. the starter moves but the engine doesnt turn over. i smell some gas in the air.. is the car running too rich? if so, why?

GliTCH

Ok, I gave in and took my car to a mechanic. The timing is off... and when he told me that I suddenly realized what happened.

In trying to get the upper front timing cover to line up properly, I had to put a lot of stress on the upper left timing cover to get it to fit back on. In doing so, I heard the plastic crack and something fell into the timing belt. Figured it was plastic but it might have been a damn screw which would tear up the belt and mess up the timing.

If you're going to do this tensioner thing yourself make absolutely sure you don't drop anything through that top timing cover, especially when you're trying to get it back on.. while the tensioner is a DIY-job, the timing belt is definitely something you're not gonna wanna mess with.

The other thing is I'm 100% sure the timing cover wouldn't fit properly because of that aftermarket tensioner. Not only does it not have the right groove for the timing cover, but the pulley is also smaller. That doesn't necessarily mean the tension isn't within Lexus specs because the spring is really where that makes a difference... anyway, just wanted to give you all a heads up. Thanks to Nomis for that write up!

SC400TT

iTrader: (4)

That is why you spend the money once, even though it is more, get the factory part, and do it right the first time. No going back, no fitment issues, no pouring more money into bad parts, or workmanship...

Ryan

EUROJulian

I instaled Dayco tensioner on my car. It was alround 10k miles ago.
Only reason being price, at 50% of the oryginal part. I was putting all front parts new on the engine, water pump, idlers T-belt tensioners, ignition, p/s pump, hoses and etc and felt like saving few bucks on that part.
Discount people had big trouble getting it to me. Took like three visits in the store to get it, not fun.

There was no instalation problems, exept for mod needed to the t-cover. Anybody instaling aftermarket parts be ready for modifications and "making" the part work. That is a reality of this bussines.
It was no biggie in the case of tensioner though.

SC400TT

iTrader: (4)

EuroJulian stated: "I was putting all front parts new on the engine, water pump, idlers T-belt tensioners, ignition, p/s pump, hoses and etc " I did all of that as well, knowing I was heading for FI, I spent the money, and put all new factory parts on, in preparation for the turbo project. I always like saving money, but I do not cut corners. In my book, that is a mortal sin... Now, if the non-factory part is better than the OEM, such as performance replacement parts, I will buy it, but this is my preference. In my experience, most Backyard DIYers are barely competent enough to replace oil, filter and serpentine belts, how the heck are they going to "mod" a new, non OEM part for proper fitment?

My $0.02 worth...

Ryan