[sparejayden]

I looked up the scheduled maintenance guide for my 2002 4cyl Highlander (2AZ-FE) and was surprised to find that there isn't a recommendation for changing the timing belt. In the "Explanation of Maintenance Items," which basically defines the maintenance items in the log it does say:

"Timing Belt - Replace every 90,000 miles. A qualified technician should perform this operation"

But when you get down to the actual maintenance log for SUVs and trucks it says at 90,000 miles:

"❑ Replace timing belt (except RAV4, Highlander with 2AZ-FE and Tacoma with 2RZ-FE or 3RZ-FE)"

Wondering if this was some sort of typo, I checked every other Gen 1 Highlander scheduled maintenance guide and found the same thing - no recommendation to change the 2AZ-FE timing belt at any mileage, of course the logs do stop @ 120k...

What do you all think about that non-recommendation?

 

[C R]

Timing chain not belt.

 

[C R]

Timing chains, guides, and tensioner will wear, stretch, and loosen which can cause reduced performance and gas mileage but Toyota claims that they last the expected life of the engine.
Of course, when thy fail, that is the end of life of the engine.
You can have a tech use their pro-level scanner to look at cam / crank timing to get an idea of wear. It will depend greatly on past maintenance. If you are trying to get it much past 200k miles then price it out and consider it.
Put it out to the forum to ask who has done it and who has had an engine failure because of it. I have a 2AZ that I hope to get to about 225k but I will probably not change it.

 

[Vangm25]

2AZ-FE is a timing chain, it or its components will wear out eventually but by that time happens either the owner has neglected its maintenance or it is over 200,000 miles and in need of a rebuild. If you want to change the serpentine belt, go for it.

 

[C R]

And water pump.

 

[sparejayden]

Thanks for the feedback. Interesting that they don't recommend a mileage/time to change it when for so many other engines they do. I think I'll take their word for it, though, and if isn't broken, won't fix it... I have some cooling problems that I am trying to figure out and think I am headed for a head gasket replacement, at the least. Pretty discouraging given I only have 106k on a 2002. But that's for another thread! Thanks!

 

[C R]

The 2AZ has a problem with head bolts pulling out. There is a kit available if you search.

 

[sparejayden]

The 2AZ has a problem with head bolts pulling out. There is a kit available if you search.

Thank you C R for the tip! after reading through the way too many posts about this problem I see that this is the issue that I have. Actually, I knew that this was my problem after the very first post I read. Sucks to have to deal with this, but at least now I feel like I know what is going on.

 

[wtdash]

Interesting that they don't recommend a mileage/time to change it when for so many other engines they do

No offense...but this is contrary to every thing I've read about vehicles with Timing Chains. Please list those vehicles w/timing chains that recommend its change.
Thanks

 

[sparejayden]

No offense...but this is contrary to every thing I've read about vehicles with Timing Chains. Please list those vehicles w/timing chains that recommend its change.
Thanks

Sorry, I am interchanging belts and chains as I am writing about this, I guess since Toyota doesn't distinguish between the two in the Maintenance guide. From your reading do engines with timing chains not have recommended replacement intervals?

 

[Vangm25]

If the timing chain is stretched beyond spec, they should be changed. By the time this happens, SOMETHING has happen.

 

[wtdash]

From your reading do engines with timing chains not have recommended replacement intervals?

As noted above and from what I've gathered over the years, timing chains don't have recommended change intervals.

I just read about a delivery driver in Chicago. He put 1 million miles on his Frontier truck w/a 4-cylinder engine. Owner did the "Timing chain replacement at 700,000 miles, that too as a precaution".

I know that certain models of Subarus w/the 3.0 H-6 and the Audi 4.2 V8 had issues w/the timing chain components - guides, tensioners, etc - that actually needed service, due to either poor design or too infrequent oil changes - but the timing chain wasn't a maintenance item, per se.

RE: the maintenance guide, see the attached. As it states in the footnotes (4) that the 1MZ-FE v6 requires a timing belt change at 90K miles. I think it does distinguish, but the owner needs to know what engine is in their vehicle. IMHO, this where having an honest dealer/mechanic comes in to play, and getting quality advice on what's due for maintenance.