Timing belt failure, 07 LC

[studawg]

The vehicle is my uncles '07 TLC with 136k. Timing belt was replaced at 91k in 2013 by Jim Hudson Lexus in Augusta, Georgia. My uncle was driving it when all of the sudden it shut off. The engine just turned off. The vehicle has power, first thought was maybe bad gas, clogged fuel filter, bad fuel pump.

Vehicle is now at an independent repair shop in the mountains of NC. The mechanic has the passenger side timing cover off, and, in his words, the timing belt is frayed and there are some chunks taken out of it. This is all we know at the moment. Sounds like to me it jumped a tooth. When attempting to crank, the mechanic said it doesn't sound right.

-Why would this happen so soon after the TB replacement?
-Is it possible that the Lexus dealership installed it improperly?
-Maybe they didnt tension the belt properly and this is the result?
-Did the attempts to crank it cause internal damage?

I don't have much experience with this situation other than what Ive read. All I know is it sounds very unusual. Im looking for some input from anyone who can shed some light on this.

 

[Rube4x]

I don't have Toyota-specific experience w/this, but did have a timing belt fail on an early 90's BMW I used to own - related to your last question on potential for internal damage....

In my situation, the timing belt happened to let go under full acceleration & near the redline (I was accelerating away from a stop light) - experienced the same feeling you described, sudden loss of all power....

Long story short - the mechanic I had the car towed to tried to crank the motor over a number of times (apparently something like 10-15 times) before "we" knew it was timing belt..... Turned out that either I (when the belt initially broke), or the mechanic while cranking the engine over so many times basically grenanded the engine! The explanation I finally got was the timing got so far "out of whack" that one of the valves broke off, was literally pushed thru the top of the piston & finally wedged itself near the crank shaft & that was bent.... I'm thinking most of the damage likely occurred when the belt first broke due to the high RPMs, but don't have any "real" data to prove.... Ended up being a new motor for me!

I would say that if the motor is cranked over too many times w/o the timing belt, you can cause internal damage.

 

[Dwight S]

Possible water pump seizure. Happened to me on a Toyota Highlander a few years back. Replaced water pump and belt and everything was fine. Just a thought...

 

[n55luvr]

Can't add much to your questions but will be interesting to hear if this vvti motor is an interference motor or not. I've seen claims of both on this forum. And I've seen claims of broken TB's causing no damage at all for non-vvti motors. If it is an interference motor and it was cranked multiple times with timing out there may be some valve damage similar to Rube's situation.

 

[studawg]

Thx for the input, I'm still all ears for more....

Update: mechanic said it definitely jumped time;

I have since learned some more info about this situation in this engine...

-That if the vehicle was at low RPM when it happened then there is usually no damage on this particular engine (luckily my uncle was in the mtns going downhill, relatively low rpm)

-The 2UZ-FE is technically an interference engine, but it depends on RPM; there is clearance between valve and piston at low RPM.

-The VVTi doesn't affect whether there is or isn't internal damage when this happens. Im not sure about this, and beginning to think it is not true.

Trying to determine if something was done wrong at Jim Hudson Lexus to determine if they should pay for the repair.

Thx

EDIT

 

[Ali FJ80]

Not sure what your mechanic is talking about, rpm has nothing to do with interference as the valves open the same height regardless of rpm.

Also having taken a head of a 2uz last night we were shocked how big the reliefs in the pistons are for the valves. Hard to see how its interference.

 

[mr jits]

Was the full service done at time of timing belt replacement? All of the "while you're in there" parts such as the water pump, tensioner, pulleys, and seals?

 

[pawwright]

...
Vehicle is now at an independent repair shop in the mountains of NC.......

What part of the NC Mountains is this in? Always good to know a good Toyota mechanic depending on location. Thanks.

 

[studawg]

Not sure what your mechanic is talking about, rpm has nothing to do with interference as the valves open the same height regardless of rpm.

Also having taken a head of a 2uz last night we were shocked how big the reliefs in the pistons are for the valves. Hard to see how its interference.

I don't know, Ive heard many stories of engines suffering damage when a timing belt broke and the same type of engine not having internal damage when it broke. Only difference being RPMs. As Rube said above, the M20B25 in E30 BMWs, many stories with differing results.

To be clear, the mechanic that has the vehicle now is not the one that told me what I mentioned above. The one that told me that is a guy that worked at a Toyota dealership for many years, performed many TB jobs there and has a lot of experience with the 4.7. He now works for a well-respected LC specialist that is prominent on this forum. During our conversation, he mentioned a clearance of .003" between valve and piston, I don't remember at exactly which point of the stroke or whatever.

But the 2UZFE is definitely listed as an interference motor by all accounts that I can find. But evidently that doesn't necessarily mean that valves and pistons will always interfere when timing is off. That then begs the question, when do they interfere and when don't they?

 

[studawg]

Was the full service done at time of timing belt replacement? All of the "while you're in there" parts such as the water pump, tensioner, pulleys, and seals?

Not sure, waiting to hear back on that very question...

 

[studawg]

What part of the NC Mountains is this in? Always good to know a good Toyota mechanic depending on location. Thanks.

Cashiers Service Center, Cashiers NC

I spoke to the mechanic doing the diagnosis on this vehicle, he sounded like he knew what he was talking about. Said he had to do a head job on a Jaguar before he could get to this one.

 

[aging fleet]

My opinion, if the techs at the Lexus store did something wrong, it would've manifested itself before logging another 45,000 miles. The water-pump, tensioner and pulleys are not part of the normal 90k service at many dealers so one of those components could've failed and caused damage to the belt.

Regarding the dealer improperly tensioning the belt, the tensioner does it for you. You simply pull the pin and tension is applied.

Best of luck and, as an owner of a vvti, I'm hoping you report back that the valves were not damaged.

 

[Manhattan]

That Cashiers shop is only 140 miles north of ACC Garage (Atlanta)... they even have a rollback. Might not be a bad idea to have a Land Cruiser specialist dig in.

 

[jgray]

I also had a timing belt break with no damage. ( big arguments in that thread too) Search the old thread I started. I also just had a misfire problem that I could not figure out and finally took it to my local Toyota dealership. Lead Toyota master mechanic that has been with Toyota for 20 years ( did my repair work ) reassured me this is NOT AN INTERFERENCE ENGINE ( despite some documentation stating otherwise). He has worked on many of the 4.7L V8's and seen others with broken belts - all with no additional damage. The 4.7L V8 came in 6 Toyota and Lexus models so it's a very common engine. I'm betting if you slap a new timing belt on you'll be fine.

 

[studawg]

My opinion, if the techs at the Lexus store did something wrong, it would've manifested itself before logging another 45,000 miles. The water-pump, tensioner and pulleys are not part of the normal 90k service at many dealers so one of those components could've failed and caused damage to the belt.

Regarding the dealer improperly tensioning the belt, the tensioner does it for you. You simply pull the pin and tension is applied.

Best of luck and, as an owner of a vvti, I'm hoping you report back that the valves were not damaged.

Thats exactly what my mechanic told me. I will update.

 

[arcteryx]

That Cashiers shop is only 140 miles north of ACC Garage (Atlanta)... they even have a rollback. Might not be a bad idea to have a Land Cruiser specialist dig in.

This. I cannot emphasize this enough. It is imperative to have a qualified shop work on your vehicles. Not all dealerships are the same. Especially if you are in a small/medium or rural town. Cruisers are rare enough so finding someone who knows what they are doing is critical.

If you read my thread about how I got my 100, the PO took it to 2 shops who said the engine was blown. This was in a large town/small city. After I confirmed the valve was stuck, I took it to my indy shop who are gurus, and they scoped it to confirm the piston was good. I gave them the go ahead to remove the head and it turned out to be some rust on the #6 valve guide. No new parts, just labor and PM. So haul it to GA if you are in doubt. And/or get is scoped. There are some new fancy ones that have 2 cameras on them so you can look all around.

Keep us posted and hope it works in your favor.

 

[studawg]

I also had a timing belt break with no damage. ( big arguments in that thread too) Search the old thread I started. I also just had a misfire problem that I could not figure out and finally took it to my local Toyota dealership. Lead Toyota master mechanic that has been with Toyota for 20 years ( did my repair work ) reassured me this is NOT AN INTERFERENCE ENGINE ( despite some documentation stating otherwise). He has worked on many of the 4.7L V8's and seen others with broken belts - all with no additional damage. The 4.7L V8 came in 6 Toyota and Lexus models so it's a very common engine. I'm betting if you slap a new timing belt on you'll be fine.

4.7 engine is an interference motor

and so it goes....

 

[studawg]

This. I cannot emphasize this enough. It is imperative to have a qualified shop work on your vehicles. Not all dealerships are the same. Especially if you are in a small/medium or rural town. Cruisers are rare enough so finding someone who knows what they are doing is critical.

If you read my thread about how I got my 100, the PO took it to 2 shops who said the engine was blown. This was in a large town/small city. After I confirmed the valve was stuck, I took it to my indy shop who are gurus, and they scoped it to confirm the piston was good. I gave them the go ahead to remove the head and it turned out to be some rust on the #6 valve guide. No new parts, just labor and PM. So haul it to GA if you are in doubt. And/or get is scoped. There are some new fancy ones that have 2 cameras on them so you can look all around.

Keep us posted and hope it works in your favor.

Normally I would agree, but the 4.7 isn't exactly a rare engine, it was put in a few million tundras, sequoias, and lexus'. We are going to have the shop where it is currently located just do the TB, WP, pulley service and give it a shot. I don't think there was any internal damage. I think either the WP or a pulley failed and caused the problem.

 

[jgray]

Mine is a 99 and broke going 60+mph. I also tried repeatedly to start is until my battery died because I was stuck in a bad storm on the shoulder of the interstate. We actually pulled the heads on my engine to confirm no valve or additional damage. I have lots of pictures. After discussing my situation with the 20 year lead master tech at my local Toyota dealership he confirmed same experiences working on hundreds of these engines over the years. I mentioned the arguments on this forum over interference vs non-interference but he again said he was confident these are not interference engines. Please post up your results after you have more details on your problem.

 

[studawg]

Mine is a 99 and broke going 60+mph. I also tried repeatedly to start is until my battery died because I was stuck in a bad storm on the shoulder of the interstate. We actually pulled the heads on my engine to confirm no valve or additional damage. I have lots of pictures. After discussing my situation with the 20 year lead master tech at my local Toyota dealership he confirmed same experiences working on hundreds of these engines over the years. I mentioned the arguments on this forum over interference vs non-interference but he again said he was confident these are not interference engines. Please post up your results after you have more details on your problem.

I confirmed with my mechanic, (again, who worked at a Toyota dealership for many years, who saw and worked on lots of 4.7s, and now works for an LC specialist prominent on this forum) about his take on the issue. I asked him specifically, in his experience, had he ever seen a 4.7 come in his shop with a broken timing belt that ended up having internal damage as a result. He said absolutely he has. He said there is .003" clearance between the piston and valve. At high RPM, the valve spring is maxed out and that clearance is reduced. He said it can be a matter of carbon buildup on the pistons/valves that can be the difference between damage and no damage. Normally, in the cases where there was internal damage, the timing belt broke when the driver was going to pass someone, maybe the engine had just downshifted, high rpms, snap, boom. He also said 8 times out 10 there has been no damage when he has seen a broken timing belt. But it does happen. Which, I guess is why the 2UZFE is officially listed as an interference engine. This would also explain why Toyota Corporate's official answer to the question is "We cannot guarantee that there will not be internal damage in the event of a broken timing belt."

One could conclude that an "interference engine" is not necessarily one in which valves and pistons will collide in the event of TB failure. If there is just a chance that they could, no matter how remote, it is technically an interference engine. Just because there have been many reported instances of TB failure happening without damage, doesn't mean its not an interference engine.

Evidently, the mechanic you speak of had personally not seen an instance of TB failure leading to internal damage, so made the assumption that its not an interference engine. I would go so far as to say that to make that proclamation, given the fact that Toyota themselves list the engine as being an interference engine, is irresponsible. Especially considering that people who hear that coming from from a "master tech" may then be less likely to proactively replace a wear part that, when it fails, can cause major and costly engine damage.

All that being said, in the case of my uncles 07 and given the circumstances under which its TB failed/slipped a tooth and changed the timing, he doesn't think any internal damage was done. He said if it were his, he would just replace TB, WP, pulleys, tensioner, etc...set timing, check the compression, and crank it up. So thats what we're doing. Ill let you know....