To the best of my knowledge, the 3.3L 3MZ-FE V6 with VVTi engine is an interference engine. The timing belt should be changed every 90,000 miles. I've changed timing belts on both the 1MZ and 3MZ and can tell the difference between the two engines when it comes to camshaft movement and metal to metal contact.

Technically, the 1MZ is not a true non-interference engine. It has valve depressions that decrease the chance of valve-to-piston interference in case of timing belt failure.

It is usually a good idea to change the water pump when the timing belt is changed, since one has everything apart and access to the water pump.

 

This site suggest it is interference:
http://yourcarangel.com/2014/07/interference-engines-complete-list/

But this site says "Conflicting information, treat as though interference":
http://www.agcoauto.com/content/List_Of_Interference_Engines

I think the Solara version of the 3MZ-FE may be slightly different than the Camry version, and may be Solara version may be interference.

 

If you don’t know. Change it


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I am not an engineer, or mechanic, so take what I say with a grain of salt. From what I read, the original 1MZ was non-interference, such as the engine on the 98-00 Sienna. But, when Toyota added variable valve timing to the 1MZ, or VVT-i (i.e. 01-03 Sienna), it would become interference IF the timing belt snapped while VVT-i was activated. I believe it would only be activated at high RPMs. So, if you have a 1MZ w/VVT-i, and your timing belt snapped while you were idling, you should be OK, whereas if it snapped while you were doing 85mph, you would not. I read that it was a similar situation for the 3MZ, where the engine was interference only at higher RPMs.

I don't want to spread wrong information, so someone please correct me if I'm wrong. But I remember reading this somewhere and drawing the conclusion that I did. I could be completely off though.

But yes, change the timing belt. Whether it's interference or non-interference, it will leave you stranded when it snaps. Change the water pump too.

 

Based off what I’ve read over the last few years....

1MZFE with non vvti should not be interference. VVTi models ... has been a debate. So far I have not come across a 1MZFE with belt valves due to an engine out of time due to timing belt failure. I have heard where a 3MZFE engine does run OK after a Tbelt going out, however I’ve heard mixed outcome. I can’t quote the user... been a long time, but engine ran okay but it would run the engine in limp mode due to the tapping of the slightly damaged valves.


Timing belts on the 1MZ enjoy a pretty long lifespan... although best to replace it when you have time.


IMO if I bought a “new” Camry with a timing belt, the first job I normally do is a timing belt job and seals UNLESs there is documented work to show everything critical was done.

 

Let's put it to rest (mostly).

1MZ, in ALL its variants, non-VVT and VVT, is NON-INTERFERENCE. They change valve timing with the phasers, but that doesn't change the valve lift, so still non-interference.

3MZ is INTERFERENCE. This is because they changed to a flat-top piston that doesn't have reliefs for the valves. Change your timing belt, water pump, tensioner, and pulleys.

It's a ways away, but on ClubLexus I promised to test VVT 1MZ interference-or-not when I get my '01 ES300 working and it's time for a timing belt job by cranking the engine hot with TB off, then checking compression. It's coming, but first trans needs replacement and I'm 30K away from TB.

 

Can completely agree with this. Backed when I worked at Lexus we had a guy mess up a timing belt job on a RX330 (3MZ) . It was a long day for him and I felt bad. But my timing belt service interval is coming up and thank goodness I can mess up and not do any damage.

 

Also, for what it’s worth. This was the original timing belt I removed from my 02 1mz equipped camry with 128k on it. I know for a fact the 1mz is non interference but I changed it anyway. Rather pay for a timing belt kit than pay for a ride in a tow truck AND a timing belt kit

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Is anybody had an issue with Aisin kit for 3mz-fe. Should I buy it or not?

 

Aisin is the OEM supplier.

 

People have asked me for years is the 3mz-fe interference or non-interference and they endlessly argue about it. This video gives the definitive answer. It also gives the link to the Aisin timing belt kit.