Non-Interference Engine
Advanced
Joined: Aug 2002
Posts: 620
Likes: 101
From: Colorado, USA
The reason he said "may" --. more than likely, it will cause damage; however, if you are at low speeds, i.e. surface streets in a high gear or at a stop (low engine RPMS) or if it failed from shutting down, it's possible it can fail and not damage the valves. It's a gamble and I don't understand why anyone would take the risk -- the odds are not in the OPs favor, but he has seen it often.
Usually, they fail at the crank gear because it has half the teeth as the cam, so sometimes shutting it down, the engine can come to a stop and crank can chug backwards or bounce off a compression stroke. Usually, a belt that is borderline toast, this rapid direction change takes out the teeth in the belt around the crank gear. The cams are under pressure from valve springs and will want to settle in the valves closed position naturally. In other words, it's possible for one bank to settle with all valves closed. In a V6 engine, it's possible it can fail and not damage valves, but if you are going high engine speed i.e. down the freeway, more than likely toast.
Usually, they fail at the crank gear because it has half the teeth as the cam, so sometimes shutting it down, the engine can come to a stop and crank can chug backwards or bounce off a compression stroke. Usually, a belt that is borderline toast, this rapid direction change takes out the teeth in the belt around the crank gear. The cams are under pressure from valve springs and will want to settle in the valves closed position naturally. In other words, it's possible for one bank to settle with all valves closed. In a V6 engine, it's possible it can fail and not damage valves, but if you are going high engine speed i.e. down the freeway, more than likely toast.
Intermediate
Joined: Mar 2021
Posts: 267
Likes: 72
From: Virginia
They have a Tensioner, some Automatic, some Not.
The Tensioners have problems related to Oiling and So On, and they need to be Serviced and occasionally Replaced.
They also have Chain Guides that Wear Out and Need to be Replaced.
The Water Pump still needs Replacing at certain intervals.
Also, Timing Chains sometimes get Noisey at High mileage, and Need to be Replaced when that occurs!
So You see, it's Not all Peaches and Cream with a Timing Chain!
Lexus/Toyota makes Great Vehicles, but, Everything Wears Out Eventually!
Remember the 3 T's!
Pole Position
Joined: Dec 2019
Posts: 2,993
Likes: 608
From: The Jet City
I wouldn't sweat 'bout chains vs belts..... Just keep up w/ the maintenence w/ whatever engine you have. Try changing the cam phazers on a 2gr vs changing the belt, w/p on a 3mz as well the cam solenoids on the 3mz are easier to change or clean vs on the 2gr. btw, I asked my wife last yr if she wanted to keep the rx & she said yeah & mentioned to take it to Greg's Japanese, so I took it to the Federal way shop & was ready to have them to drop the engine/cradle for, what I thought to reseal the timing cover. It turned out to be the oreilly reman p/s pump which was leaking. I originally had the pump replaced before we brought it home yrs ago w/ a reman oreillys pump. Last Januuary had the pump replaced again (Gregs @ Southcenter) & I had them replaced the high pressure hose as well. Turned out to be the high pressure hose was stripped in the pump. Now on the 4th pump & no leaks.
Thread Starter
Rookie
Joined: Feb 2023
Posts: 29
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From: VA
3mz
I wouldn't sweat 'bout chains vs belts..... Just keep up w/ the maintenence w/ whatever engine you have. Try changing the cam phazers on a 2gr vs changing the belt, w/p on a 3mz as well the cam solenoids on the 3mz are easier to change or clean vs on the 2gr. btw, I asked my wife last yr if she wanted to keep the rx & she said yeah & mentioned to take it to Greg's Japanese, so I took it to the Federal way shop & was ready to have them to drop the engine/cradle for, what I thought to reseal the timing cover. It turned out to be the oreilly reman p/s pump which was leaking. I originally had the pump replaced before we brought it home yrs ago w/ a reman oreillys pump. Last Januuary had the pump replaced again (Gregs @ Southcenter) & I had them replaced the high pressure hose as well. Turned out to be the high pressure hose was stripped in the pump. Now on the 4th pump & no leaks.
Thread Starter
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Joined: Feb 2023
Posts: 29
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From: VA
Found this statement in a specifications document.
"The 3MZ engine has aluminum cylinder heads with four valves per cylinders and belt-driven double overhead camshafts. The engine uses a timing belt to drive the exhaust camshafts only and those, in turn, rotate the intake camshafts through gears. Toyota's 3.3L MZ engines were always produced with the Variable Valve Timing - intelligence (VVT-i) on the intake side. Hydraulic lifters for the intake and exhaust valves are not provided."
"The 3MZ engine has aluminum cylinder heads with four valves per cylinders and belt-driven double overhead camshafts. The engine uses a timing belt to drive the exhaust camshafts only and those, in turn, rotate the intake camshafts through gears. Toyota's 3.3L MZ engines were always produced with the Variable Valve Timing - intelligence (VVT-i) on the intake side. Hydraulic lifters for the intake and exhaust valves are not provided."
Thread Starter
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Joined: Feb 2023
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From: VA
Called a local Toyota dealership yesterday to get another quote for replacing the timing belt and they stated they would not replace the belt on my RX330. I ask if they would replace the belt on a Camry, answer was of course. My answer, exact same engine for that year and model. Same engine, almost same procedures. Just stupid in my book.
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Intermediate
Joined: Mar 2021
Posts: 267
Likes: 72
From: Virginia
Called a local Toyota dealership yesterday to get another quote for replacing the timing belt and they stated they would not replace the belt on my RX330. I ask if they would replace the belt on a Camry, answer was of course. My answer, exact same engine for that year and model. Same engine, almost same procedures. Just stupid in my book.
He's trying to figure out if he wants to spend the $$$$ to fix it, or just get rid of it!
He has 215K miles on it, and that was the 2nd T'belt that was installed, at 95K miles.
Yes, it's a Interference Engine!
Thread Starter
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Joined: Feb 2023
Posts: 29
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From: VA
Finally, I found a Toyota dealership that is quoting the job. He also stated their labor is lower than the Lexus dealership. I'll post what I find out. They will also give a 1year warranty too.
Advanced
Joined: Aug 2002
Posts: 620
Likes: 101
From: Colorado, USA
My buddies '04 RX330 broke the timing belt last week, he was going 40mph, and he just told me, the engine is now Trashed!
He's trying to figure out if he wants to spend the $$$$ to fix it, or just get rid of it!
He has 215K miles on it, and that was the 2nd T'belt that was installed, at 95K miles.
Yes, it's a Interference Engine!
He's trying to figure out if he wants to spend the $$$$ to fix it, or just get rid of it!
He has 215K miles on it, and that was the 2nd T'belt that was installed, at 95K miles.
Yes, it's a Interference Engine!
Personally, I have trusted MDT Tech (The Master Toyota Tech I quoted) since around 1998 and he has never steered me wrong.
Good for OP to get it replaced.
Thread Starter
Rookie
Joined: Feb 2023
Posts: 29
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From: VA
I'm excited, Toyota provides a 1 year warranty on the timing belt and water pump replacement. Will be nice to get that behind me. Recently sold my aged Ranger and bought a used Forester which will be my run around vehicle. And by the way it has a timing chain. One less thing to worry about. I'm a maintenance freak, in case know one has figured that out yet.
