I am preparing to change my timing belt and water pump in about 2 weeks.

I have the (OEM) belt and water pump and gaskets.

Should I change the tensioner bearing and idler bearing? What about the hydraulic tensioner?

I saw kits online with those included or addons. Wondered if I should change them or not?

Are they a lot of work? How often do they go bad?

Depends upon your mileage. If you have under 200K miles you are probably OK, over 200K then you may want to change them. Bearings wearing out is the usual cause of failure.

Thanks. If the bearings fail, does it so many damage, or does it retain, yet make noise? Or do they usually freeze up and burn/melt the timing belt?

I'm about 160-170k.

Sorry if this sounds like dumb Q's.

When my TB was replaced at 172,000 miles, the dealer replaced one of the tensioners (cannot remember which one) and the water pump. The only real way to determine the condition of the bearings is to spin them with your hand to see if they are tight and smooth.

I would recommend you replace them if you plan to do the entire TB replacement (Timing belt, water pump, tensioners, seals, etc.) The extra money for for these parts is an inexpensive insurance policy against future mechanical failure.

Aisin TKT-021 kit arrived today, complete kit, including tensioner, for my 2004 V8 4Runner Limited.

We're installing it all on Sat am. Any words of wisdom?

I'm going to wash the engine compartment tomorrow to help avoid dirt contamination.

It's a pretty simple job really. The hardest part is usually breaking loose the bolt for the harmonic balancer.

The timing belt, thermostat, coolant change and water pump are DONE!

The biggest problem we had were some cheap-a$$ bolts. Broke one in the top square portion of the top water tube, and one on the right cam cover. A nut was bad on the left came cover and one bolt wouldn't come out at all on the left cam cover, prefering to break out of the left cam cover completely.

Easy outs are essential tools!

Fortunately, I have a 5 gallon bucket of misc metric bolts and nuts. Picked them up at a local flea market a few years back, probably out of a garage

I took a few pics I'll share once I get them off my tablet and resized.

It was tricky to get the timing marks lined up on the crank and then on the top cams.

We replaced all the idler, tension pulleys and the tensioner. The idler pulley hadn't failed, but I could feel a little slop and grittiness in it. I was glad we changed it and the others.

Found the water pump gasket had a small leak.

The coolant has NEVER been changed or serviced in any way. Over 160k and 10 years, but the radiator and all the chambers looked BRAND NEW! I'm glad we refilled it with genuine Toyota SLLC (pink). It was expensive, but after this, I am a believer!

So, how was the timing belt you ask?

The belt looked to be in okay shape at first glance. But the square profile of the teeth were a bit trapezoid in shape and shiny. It had not jumped any teeth, but as my buddy showed me, when both cams were lined up with the marks, the crank was between 10 and 20 degrees off to the driver's side (advanced timing)!

Talk about S-T-R-E-T-C-H!

The results? Much crisper throttle response, a very significant decrease in the mid-rpm power dip, and it felt like better performance. I'm guessing with that far out, The ECU (or possibly the ECU?) could have been advancing the timing for the performance power curve, but with the belt stretch, it got too aggressive and had to be retarded.

I don't know if this is so, but it would explain the hesitation and power sag. The power, rpms, and acceleration seem much more continuous. I have a slightly modified exhaust that I remember added power to the mid-rpm, but didn't realize how it has been fading over the years...frog in water thing, I guess

This job took us about 9 hours with the broken bolts and looking for replacements. I also wasted (a ton of) time looking for O-rings that I didn't realize were in the kit already and using easy outs and drilling the upper square coolant bolt hole.

Moral of that wasted time? Open your parts and look at them BEFORE getting too deep into your project! I was excited to get this done and neither of us slept much the past few days (we shared that story as we were dragging butt when we met for breakfast) and didn't think about it.

I also took the opportunity to clean up some of the plastic parts while they were out on the ground. Dollar store imitation Simple Green in a spray bottle, a small round scrub brush with stiff plastic bristles and a long handle, and a hose.

Oh- and I ordered 10 replacement plastic 'rivet' style fasteners/clips for the plastic bits. I need some more, but this was what I could get quickly for about $1 each. I plan to order more for various locations.

In retrospect, I would DEFINITELY RECOMMEND you change your timing belt about 100k miles. Not because of impending FAILURE of the belt, but because of the decrease in performace due to a stretched belt! In my case, the different is quite noticeable, even without the "I should have had a V8" head-smack

Hope this is helpful to others thinking of this job or putting it off like I did.

Sounds like everything worked out well for you! I plan to do same job this fall.

Did you replace the front main seal behind the harmonic balancer?

No, hadn't thought about it. Didn't have any leaks or anything, except for the water pump GASKET (not the bearing seal!).

I'm not sure how common problems are with it or how big a job it is? If it wasn't for the A/C being hard lines, I probably would have removed the radiator and condenser, which would probably make a job like that a bit easier.

I have a tank of R134a, vacuum and gauges here, but dread cracking a system that is functioning properly.

Here's a link to my main thread with more info and pics.

Lots of overdue service items- catching up, input?

Not quite a writeup, as people doing those do a very good job, but I point out a few things and share a couple of experiences that may help for the next guy doing it.

Have some extra bolts handy. We broke a couple and had some trouble with others.

I'm dreading forcing the stuck PCV valve out, been spraying it a bit and giving it some time.

As I mentioned, replacing the belt was worth the hassle just for the improvement in performance due to the timing!

I've been chasing this problem for a bit, looking to do some performance upgrades for this "tired" engine. But it seems it isn't tired at all

I wasn't expecting any performance changes, only looking to extend longevity, but was quite pleasantly surprised and wanted others deciding when to schedule this work to know about that benefit.

Thanks for the report.

A couple of very interesting nuggets, above.

I've dug around and haven't quite found a good answer for this and this thread has had the most talk of belt tensioners.

I'm trying to track down the size and thread spacing for the power steering belt tensioner bolt. Mine sheered off. I'm working on an '87. Any help would be appreciated.