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- #61
This just in...My mechanic looked into the cylinders with a borescope and inspected the tops of the pistons and found no evidence of collision with the valves.
Air cleaner blew up, won't start now. Oh god...
- Thread starter LCtygrys
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Since we're all throwing theories out I'll say the tensioner or idler bearing seized and side loaded the camshaft pulley and snapped her up.
More evidence that this is NOT an interference motor! Can any of our resident pro's explain how this could be if it is an interference motor?
Doesn't mean that it's not, just means that so far, in the limited realm of Mud, no one's seen valve damage from a tb break. As Torfab said earlier, he's rotated the cams manually and felt the valve contact.
I still want to know what those scores are. And should that be all oily? That looks bone dry, not wipe down dry.
I have to say that these holes are very interesting. If they were put in as an intentional fail mechanism to save most of the engine, well, that may well have worked and saved the day. Sure is a clean break. Of course, you don't want something like that to work *too* well...
So, what's the rest of the damage consist of finally?
(I don't think you want too much oil around a belt.)
So, what's the rest of the damage consist of finally?
(I don't think you want too much oil around a belt.)
Of course not. My assumption was that the fracture was inboard of the cam seal and that those are wear marks on the hub where it fits into the seal.
- Thread starter
- #71
Full damage reports not available yet Captain. Once the Klingon ships are gone we'll have a better look. In other words my car was dropped in his lap and he still has others in front of me...So far the air filter, the pipe from the air filter to the front of the engine, the top engine cover, the cam sprocket, the timing belt, probably the cam, the sprocket cover, and a couple of sensors that were in the wrong place at the wrong time. And of course my poor wallet. It is quivering in silence waiting for its sentence to be handed down.
I'm pretty sure those grooves are a mechanical 'fuse' to save the innards and did their job but time will tell.
Lovely cars, these....
I'm pretty sure those grooves are a mechanical 'fuse' to save the innards and did their job but time will tell.
Lovely cars, these....
I think it's an interference engine so well engineered by Mr T it never interfere's.
The sheared off cam pulley would be my biggest concern(aside from whether or not the engine is an interference design).
Can you rotate the camshaft freely on either side?
Typically cam gears don't just shear off and a bound up idler pulley is unlikely to cause this. I would look for oil starvation in one of the cam bearings and/or an overheating condition that would cause the cylinder head to warp ultimately seizing the camshaft. It will be very apparent the aluminum bearing surface will be galled and some will likely be damage to the cam journal itself.
TP
Can you rotate the camshaft freely on either side?
Typically cam gears don't just shear off and a bound up idler pulley is unlikely to cause this. I would look for oil starvation in one of the cam bearings and/or an overheating condition that would cause the cylinder head to warp ultimately seizing the camshaft. It will be very apparent the aluminum bearing surface will be galled and some will likely be damage to the cam journal itself.
TP
Sounds like more good news OP!
I agree with Trunk Monkey. Just because we haven't seen someone eat a valve doesn't mean it can't. To be classified as a non-interference engine it has to have a 0% chance of one getting smashed by design. As we all know the 2UZ-FE is one of the TIGHTEST engines Mr T makes. So if there is a 5% chance of a valve getting smoked it's an "interference" motor. Just because the odds are in our favor doesn't mean it's not a possibility. I would bet when somebody shreds a belt with the 2uz in the far upper RPM band and we will put this theory to bed...
From Tundra Solutions:
"FYI, it is an interference engine, saw the damage first hand. I replaced my belts every 60k, but guess what gave out, the timing belt tensioner, not the belt. The belt was loose enough to have the pistons slam 10 of the valves and bend them. I had three choices, buy a new truck, which I can't because the new redesign is yet to be released, buy a rebuilt, or fix it. Since option 1 is out, I checked into option 2. My buddy owns a large truck wrecking yard and would give me an engine with low mileage for 1500k. I would then have to replace certain elements, not knowing the condition, timing belt, oil pump, etc as I always like to error on the safe side. Total bill close to 5k, and an uncertain feeling on the engine and its quality, i.e. was redlined, oil changed, etc. The last option, have Toyota fix it. A complete top end rebuild, and major service. Total bill, $ 4,100.00, not as bad as I thought. I did this for one main reason. I tore the whole engine apart, and mic'd everything, and unbelievably everything shows hardly any wear and is way within tolerance. I figure it is better to keep with what I know, and I should not have any problems. It was funny to see almost no carbon buildup on the pistons, running 87, and no ring wear marks in the walls of the cylinder holes."
I agree with Trunk Monkey. Just because we haven't seen someone eat a valve doesn't mean it can't. To be classified as a non-interference engine it has to have a 0% chance of one getting smashed by design. As we all know the 2UZ-FE is one of the TIGHTEST engines Mr T makes. So if there is a 5% chance of a valve getting smoked it's an "interference" motor. Just because the odds are in our favor doesn't mean it's not a possibility. I would bet when somebody shreds a belt with the 2uz in the far upper RPM band and we will put this theory to bed...
From Tundra Solutions:
"FYI, it is an interference engine, saw the damage first hand. I replaced my belts every 60k, but guess what gave out, the timing belt tensioner, not the belt. The belt was loose enough to have the pistons slam 10 of the valves and bend them. I had three choices, buy a new truck, which I can't because the new redesign is yet to be released, buy a rebuilt, or fix it. Since option 1 is out, I checked into option 2. My buddy owns a large truck wrecking yard and would give me an engine with low mileage for 1500k. I would then have to replace certain elements, not knowing the condition, timing belt, oil pump, etc as I always like to error on the safe side. Total bill close to 5k, and an uncertain feeling on the engine and its quality, i.e. was redlined, oil changed, etc. The last option, have Toyota fix it. A complete top end rebuild, and major service. Total bill, $ 4,100.00, not as bad as I thought. I did this for one main reason. I tore the whole engine apart, and mic'd everything, and unbelievably everything shows hardly any wear and is way within tolerance. I figure it is better to keep with what I know, and I should not have any problems. It was funny to see almost no carbon buildup on the pistons, running 87, and no ring wear marks in the walls of the cylinder holes."
Wait, so this guy had already replaced at least two belts himself at 60K each, and had the chops to tear down and mic his whole engine, but paid Toyota to do the rebuild??? 
excuse me while I file away both the story and the prices in the "huh, I dunno about that" file...
excuse me while I file away both the story and the prices in the "huh, I dunno about that" file...
Oh no doubt he could very well be FOS, it's the interwebz yo! 
Here's a few more stories to think about/disregard/file away: (note these are not from a belt letting go going down the road but sound like botched t-belt jobs which illustrate a point from yet another perspective. Also showing that when crap gets out of timing crap can definitely get smashed.)
Tundra 4.7 bent valves - Interesting info on valve adjustment in this one.
Sequoia 4.7 bent valves - This one just made me
Here's a few more stories to think about/disregard/file away: (note these are not from a belt letting go going down the road but sound like botched t-belt jobs which illustrate a point from yet another perspective. Also showing that when crap gets out of timing crap can definitely get smashed.)
Tundra 4.7 bent valves - Interesting info on valve adjustment in this one.
Sequoia 4.7 bent valves - This one just made me
Tundra and Sequoias only. LCs and LXs are immune because Toyota puts extra fairy dust on them when they build them. Plus they're more awesome...
Damage report update? I am fascinated by this. Hoping you have found a way to recover!
There may actually be some truth to this? SWUtah posted an interesting article in the 200 section indicating the 5.7L used in the LC and LX is built in Japan under the Master Guild program while the 5.7L in the Tundra and Sequoia is built in Alabama. Perhaps the same goes for the 4.7L? Hence why there is evidence of piston-valve contact on the 4.7L Tundra and Sequoia, but not LC?
https://forum.ih8mud.com/threads/ar...re-the-engine-is-built-for-200-series.849003/
@RND1 I thought something like that was already true. When I was doing my internet/travels research I read where the LC/LX 4.7's were made in Nippon, while the Tundra/Sequoia engines were made down south. There was something about the Nipponese engines having forged conrods while the US ones have cast ones. This was in discussions about supercharging- as well as other areas.
I dunno, is it possible there is a cheaper to build/mass production friendly interference 4.7 built here and a more expensively built/crafted non-interference version made in Japan? Building different engines from the same block has been done before- see Chevy 230/250 I6 vs. Pontiac OHC 6.
I remember the buying advice used to be, if you have a choice between a US-built specimen and a Japanese one, get the one made in Japan....
I dunno, is it possible there is a cheaper to build/mass production friendly interference 4.7 built here and a more expensively built/crafted non-interference version made in Japan? Building different engines from the same block has been done before- see Chevy 230/250 I6 vs. Pontiac OHC 6.
I remember the buying advice used to be, if you have a choice between a US-built specimen and a Japanese one, get the one made in Japan....
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