DIY: 2005 Sienna 3.3L 3MZFE Timing Belt (2023)

DIY: 2005 Sienna 3.3L 3MZFE Timing Belt

Just helped a friend do his Timing Belt at 115K. I don’t want to write a comprehensive DIY since there are some very good info on the web.

If you are reading this, chances you are NOT a novice. This job difficulty is about level 7-8 out of 10. So if you are new to car repair, I strongly recommend that you pair up with someone with experience.

See the attached pdf, it is an excellent pdf!

Another excellent you tube video (for 1MZFE but similar idea for 3MZFE). If you don’t replace the WP, then skip those steps. See the youtube video below.

Should you decide the replace the WP, search the web for a trick to do it WITHOUT removing the cam sprockets and inner timing cover (which is a pain). There is a way to loosen the inner TB cover only enough to lift the WP out.

You NEED to read the pdf and watch the youtube, it will make your life easier.

My comments below serve as:
- My additional experience, trick, tips.
- How to deal with broken bolts!!!


- PS Belt and Alt/AC belt from Toyota dealer ($6 and $21).
- Aisin TKT-026 TB Kit, about $180 on amazon. If you don’t replace the WP, save it for later.

- 10-mm, 12-mm, 14-mm sockets.
- 10-mm, 12-mm, 14-mm offset wrench would be useful.

- 17-mm offset box wrench to move cam sprocket.
- 17-mm socket in case you remove engine mount nut to jack the engine up (a step I don’t think you need to do! Read on).
- Air Impact 1/2" Air Impact and 22-mm Impact Socket for the crank bolt.


1. Spray bolts with PB Blaster a few days before the job. I did not, so one of the bolts was broken a pain to drill it out, read on.
- Clearly label all nuts and bolts during removal, this will make installation mush easier because this is a long prcess!
- For installation, I use a small drop of Loctite on any bolts that have to do the TB system (idler pulley, tensioner pulley, HT, Crank Pulley). This is just my method.

2. Car on level surface, rear wheel chocked, RF tire removed and placed 2 jackstands below subframe for safety. Do NOT do this job with the car on floor jack only, unless you want to die!

3. Alternator Belt ---> 3 bolts to mess around with:
- Loosen (Do Not remove) the Alternator Pivot Bolt: 14-mm.
- Loosen the 12-mm LOCK bolt, this bolt locks the belt in with proper tension.
- Then loosen the ADJUSTING Bolt to release the belt.
NOTE: during installation, tighten belt so you can barely twist the belt 90-degrees. Look up on the web how to check belt tension. You want to apply correct belt tension.

4. PS Belt ---> three (3) 12-mm bolts to mess around with but the pivot bolt is difficult to get to. I was lucky I didn’t have to mess with the pivot bolt, I could push the PS Pump Up and Down with a screwdriver.

5. Unclip the wiring loom from the Upper TB Cover.

6. Remove UPPER TB Cover (10-mm bolts).
NOTE: during installation, the UPPER TB Cover lowest bolt position goes on the OUTSIDE of the LOWER TB Cover.

7. In order to remove LOWER TB cover, the crank pulley has to be removed first.

- Unless you have the special tool to hold crank pulley, then mark the 22-mm bolt in relation to the pulley! This helps re-installation with impact tool.

- Impact tool didn’t work for me (rated up to 400 ft-lb). So I used the starter trick as in youtube video (time marking 2:20 on video), worked like a charm. The trick is: have a 2nd person to bump the starter for ONLY 1-2 seconds!

- Note on crank pulley removal tool. Again see the youtube video. The gear removal tool is about $15 at auto parts store. I temporarily install the 22-mm bolt so the tool can have leverage against the 22-mm bolt to pull the Crank Pulley. The key thing is: the gear removal tool has a center bolt that goes in the center, if you are NOT careful, this bolt can go into the crank and damage the threads and game is over!!! Again, temporarily install the 22-mm bolt before using this gear removal tool.

8. Mark the TB Metal Guide so you know which side faces you (the concave side faces you).

9. NOTE on "dogbone" mount: one bolt broke even with PB Blaster.

*** NOTE on side mount. Again, watch the youtube video. I broke one of the two long bolts.
- New bracket is $40 at dealer. It was Sunday, so we had to drill the old stud out of the bracket (I took a good 1.5h to drill it out), then use new bolt/nut from Home Depot because during drilling out, the threads in the side bracket are damaged.

*** NOTE: you can remove the side bracket without raising engine. I remove the nut holding engine mount (on driver side) and jack the floor pan near the pulley edge but almost dented the oil pan, even with the use of a piece of wood and rubber. So, I advise against jacking the oil pan!

*** The side bracket barely clear the body panel, with some wiggling, you can take it out. Or use a piece of wood the somehow wedge the engine against the sidewall a bit to clear the side mount. You just have to find a safe spot to wedge it.

10. Set the crank, cam at proper marks as in the video.

11. Removing the idler pulley, tensioner pulley and tensioner itself is straightforward.

12. The new tensioner is already compressed with a pin. Do NOT remove the pin until you have rotated the crank pulley by hand twice while watching the cam!
- If you re-use the tensioner, then compress the tensioner with a vise VERY VERY slowly. It make take 5-7 minutes to do to avoid damage to the seals!

13. For new TB: I noted that Mitsuboshi dotted yellow line for the Crank Pulley was NOT accurate. If you blindly follow the yellow marks on this TB, you WILL be screwed. So I changed the sequence a bit:

- FRONT Cam Sprocket (line the belt to the Solid Yellow mark), make sure the cam sprocket line up with the tiny mark on the INNER TB Cover, use a small spring clamp (or zip tie or clothline clip) to hold the TB to the cam.

---> WP

---> Crank Pulley (making sure all teeth are engaged)

---> REAR Cam Sprocket: this is the most difficult part b/c of limited vision. I used a mirror but due to the angle it was difficult to tell if the alignment was good. The cam moved so I used the 17-mm box wrench to re-align it! Then I found a neat trick: with bare hand, feel the tiny mark on the Exhaust Cam, point the finger across the new TB ---> straight toward the engine and you will feel the tiny depression on the Inner TB Cover. So, if you finger tells you the Exhaust Cam lines up with the mark, you are good. I find this trick better than the mirror due to the angle of the mirror.

---> Last is to have the TB on the Tensioner Pulley: it was difficult but again found a neat trick: 17-mm box wrench on the Exhaust Cam and go counter-clockwise a bit. This will give enough slack for the belt to slide onto the tensioner pulley.

14. Again, don’t pull the pin on the Hydraulic Tensioner, until you have rotated the Crank Pulley for 2 revolutions by hand!

15. Verify that all crank/cam marks line up (recall the finger trick for Exhaust Cam?), then pull the grenade pin lol…
- If you are off by one tooth, then you have to remove the Hydraulic Tensioner, re-compress it and start with all the blah blah blah again.

16. If you place a Spring Clamp or zip tie on the TB, remove it.

17. NOTE on side engine mount: broken stud had to be drilled out. It was a 1.5h pain. New bolt/nut from Home Depot solved this problem. Bring your old bolt to Home Depot to get a match. Factory is M9 bolt, I used some SAE bolt because HD does not have metric bolt that long. Anyway, use your creativity.


Basically the reverse of removal, but I learned this the hard way, so here you go lol…

1. TB Metal Guide: Remember which side faces you! Now STOP.

2. Engine Side Mount. One nut goes with the Alternator Bracket!

3. LOWER TB cover.

4. UPPER TB cover (the bolt near the firewall is a bitch). Make sure the “shared bolt” the connects the Upper and Lower TB cover is on properly.

5. NOTE on Crank Pulley: used the Air Impact and bring it back to factory marking.
I used a bit of Loctite here but didn’t see any Loctite from factory.

6. PS Belt: Use a screwdriver on the bracket to apply adequate tension on the PS Belt, then tighten the adjusting bolt, then the other bolt.

7. Alternator/AC belt: same deal. Make sure the tension is correct then tighten all three (3) bolts: pivot, locking and adjusting bolts.

8. Mentally check all bolts, nuts. Did you pull the pin on the Hydraulic Tensioner etc.

9. Verify that the wiring loom is secured back onto the UPPER TB Cover.

Again, double- and triple-check everything before firing up the engine.

That is all boys and girls, Good Luck!

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