Can a timing belt change make an engine fail? (2 Viewers)

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i've seen "oem" timing belts break or jump. come to find out cutomer bought them off ebay or amazon and where labeled oem but were chinese garbage.
BEWARE!
 
This 2uz question has been beaten to death and I’ve been under the impression that pre VVTI is labeled “interference” but I’ve seen posts on Tunda/T4R/and mud like this from a really old thread. Do we have a broken belt that destroyed a pre VVTI engine?
I can personally vouch that you can turn the crank on a >>>pre-VVTI<<< motor all the way over by hand with the timing belt off. VVTI, that apparently is not the case.

ugh, why did I contribute to continuing this thread???
 
the non VVT-i engines are non-interference so the 50 degree setting shouldn't matter, at least from a damage prevention measure.
All 2uzs, regardless of model year or whether they have vvti or not, are technically interference engines. Toyota makes this very clear in the FSMs:

2FCC39F4-6618-4A11-8953-624466548B5A.jpeg


However, for whatever reason, timing belt failure on the pre-vvti 2uzs is often not catastrophic. Perhaps @2001LC has a technical explanation for this, as I have yet to figure out why it’s rarely destructive on those pre-vvti 2uz engines.



It does bear noting that you do end up rotating them back to TDC at the end of the job, leading me to believe that the 50 degree setting is just to allow the cam to rest at it's lowest energy state.
That’s only after all the timing components are completely installed, and is simply a check to ensure the cams and crank are in fact in time with one another after turning 2 full revolutions. In contrast, the belt is installed with the cams and crank all advanced 50* clockwise, just as they are when removing the belt. Again, Toyota is very clear about why 50* advance is required in all of the FSMs: to prevent the piston and valve heads from making contact and causing damage.
 
All 2uzs, regardless of model year or whether they have vvti or not, are technically interference engines. Toyota makes this very clear in the FSMs:

View attachment 3157269

However, for whatever reason, timing belt failure on the pre-vvti 2uzs is often not catastrophic. Perhaps @2001LC has a technical explanation for this, as I have yet to figure out why it’s rarely destructive on those pre-vvti 2uz engines.




That’s only after all the timing components are completely installed, and is simply a check to ensure the cams and crank are in fact in time with one another after turning 2 full revolutions. In contrast, the belt is installed with the cams and crank all advanced 50* clockwise, just as they are when removing the belt. Again, Toyota is very clear about why 50* advance is required in all of the FSMs: to prevent the piston and valve heads from making contact and causing damage.

I've not done an exhaustive search on parts (pistons, valves or lift of cams lobs different) and their dimensions. PN's will not tell the whole story. Actual dimension would need looked at. But I believe it's the piston has greats difference.

What I do know: We don't have confirmed interference, in any non VVT. We do have confirmation of interference in the VVT.
 
Thank you everyone so far. The kit that was used was WP DAY 89255 for accessory tensioner and WP AIS TKT-021 as the belt kit. I recall the shop saying they will use OEM parts...but looks like this is not but a very common kit.
 
I don't know about the tensioner, but Aisin is OEM for the timing belt kit.
Just wanted to inform that AISIN is owned by toyota and also supplies parts to other car brands. However, the AISIN part comes in a TOYOTA box/package is far too superior to just a part made by AISIN inside an AISIN box. It is not a toyota scam to make more money. The engineering going into a AISIN part inside a Toyota box is very advance. I have experienced it on my lifetime of dealing with OEM parts and AISIN parts. I used AISIN T-belt kit because it is the next best part and I will replace it based on the years not miles.

OP: Be there and make sure the timing is correct inside the engine. If it is bad, then the issue may be serious. I just don't want them to call it is a bad engine and throw a good engine into waste.
 
@nissanh Good info, I noticed quite the price difference for a Toyota air fuel sensor vs Denso air fuel sensor. Not a few $ more like $70. Denso supplies Toyota afaik.

OP: To be quite honest I wouldn’t trust much from what this shops says (same ones that installed I assume), telling you before they even open anything that you could be looking at a new motor. Already prepping you for the big bill. These motors don’t just die, and it ran fine for a couple hundred miles after the belt… seems suspect. Regardless of what they think, I’d pay for a tow to another recommended shop or at least buy a close MUD member some booze. Or if they repair on their dollar still get it checked afterwards.

When my local mechanic misses something he’s more than willing to get me back in and make it right, I think it happened once trying to save a few dollars and replaced one sensor instead of both. Guy even took pictures when he did my t belt.
 
The OP asked, can the T-belt service lead to engine failure (failure meaning: not fixable, short of major rebuild of long block). In the VVT YES! by all accounts I've heard of. But I've never actually diagnosed a VVT failure, due to a bad T-belt service. But have had a Toyota Service manager tell me of a case, that happen in their shop. When a tech timed to the "T's". They bough client an engine. They would have surely scoped the cylinder before shelling $$$ out for and engine.


Aisin vs Toyota Aisin:
Aisin T-belt kit only has water pump and perhaps it's gasket, that are Aisin in side the box!

I have compared Aisin to Toyota Aisin. With parts like the Water pump, fan bracket and few others. In most cases, you can visibly discern a difference in the metal. Toyota is shiner almost like polished finish. IMHO reason is: Toyota is manufacture to a higher standard. That said they are both excellent parts.

Same applies to Denso. Some parts there is no difference, other there is. Denso (support) told me, yes Toyota in some cases, is manufacture to higher standard. But like in the case of coil (COP), we see Toyota's name ground off. Denso said: that's a parts Toyota gave Denso permission to sell in secondary market.
 
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This is a weird question but roughly 400 miles after a timing belt replacement on an 06 lx470 with 184k on it...maintained well and up to date just had apparent engine failure. One different mechanic said we can't crank the car and it sounds like valves are hitting or something. Timing tensioner is tight... belt in tact but they couldn't access the timing marks to see if they were off or not.
When engine interferes, it's valve(s) hit the piston head(s). It will not run or run very poorly at time of interference.

If ran okay for 400 miles. I'd look very hard first at; Cam & Crank senors wires. The crank sensor wire is very often miss routed, and rubs on drive belt.
Crank wire routed wrong.JPEG
Engine wire harness main (1)a.JPG



If they check out. I'd pull both top t-belt covers, and check timing. If marks off, I'd scope the cylinders.


I've seen where a tech did not use torque wrench, or just forgot to tighten pulley bolt. Bolt was falling out and pulley wobbling. Me, I mark all bolts when torqued. No mark, I get out the torque wrench, regardless of what I think I did.

IMG_1297.JPEG
 
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The OP asked, can the T-belt service lead to engine failure (failure meaning: not fixable, short of major rebuild of long block). In the VVT YES! by all accounts I've heard of. But I've never actually diagnosed a VVT failure, due to a bad T-belt service. But have had a Toyota Service manager tell me of a case, that happen in their shop. When a tech timed to the "T's". They bough client an engine. They would have surely scoped the cylinder before shelling $$$ out for and engine.


Aisin vs Toyota Aisin:
Aisin T-belt kit only has water pump and perhaps it's gasket, that are Aisin in side the box!

I have compared Aisin to Toyota Aisin. With parts like the Water pump, fan bracket and few others. In most cases, you can visibly discern a difference in the metal. Toyota is shiner almost like polished finish. IMHO reason is: Toyota is manufacture to a higher standard. That said they are both excellent parts.

Same applies to Denso. Some parts there is no difference, other there is. Denso (support) told me, yes Toyota in some cases, is manufacture to higher standard. But like in the case of coil (COP), we see Toyota's name ground off. Denso said: that's a parts Toyota gave Denso permission to sell in secondary market.
Good to know, Denso coils are the only part I haven't purchased from the Toyota parts counter.

Every time someone replaces something with an aftermarket part, a little bit of the land cruisers soul dies inside as it becomes less of a cruiser =[


OP , keep us posted. Since you drove a while after the repair it makes me think it was at least initially done the right way. Maybe you can bring up that 50 degree off set comment others were mentioning, just to see how they respond and if they know what they are doing.
 
I replaced the timing belt a couple of weeks back, and it went smoothly. The AC compressor's nuts and bolts gave me the most significant problems. I have to spend easily two hours playing with them. After putting everything back, I only had three extra bolts. Crank 1st time, and no issues so far.
 
better to have too many bolts at the end than not enough, cuz I'd be wondering if I lost a bolt someplace inside the engine. Not good for peaceful sleep... :)
 
Howdy! So the engine is almost out- the mechanic said everything is tight on the belt side, marks look good but they will have to take off the head. They also mentioned possible oil pump failure? They are very apologetic since the car was running perfectly then suddenly dies- as a customer/consumer I prefer can't stomach that it was something else that killed a strong running car with no prior issues- they will keep digging and give me an update after the weekend.
 
When engine interferes, it's valve(s) hit the piston head(s). It will not run or run very poorly at time of interference.

If run okay for 400 miles. I'd look very hard first at; Cam & Crank senors wires. The crank sensor wire is very often miss routed, and rubs on drive belt.
View attachment 3159124View attachment 3159125


If they check out. I'd pull both top t-belt covers, and check timing. If marks off, I'd scope the cylinders.


I've seen where a tech did not use torque wrench, or just forgot to tighten pulley bolt. Bolt was falling out and pulley wobbling. Me, I mark all bolts when torqued. No mark, I get out the torque wrench, regardless of what I think I did.

View attachment 3159117
This is good info! Thank you.. they mentioned things are routed properly and lines up/tight but will keep digging...
 

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