Please advise…Timing belt tensioner go bang.

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Well wish I would have investigated cylinder 1 more yesterday. I put it all back together and started to put in the spark plug and remembered. It’s way worse. I don’t know how I didn’t see it but I guess being at tdc was blocking the view with the rounded center of the valve. Once I dropped it in the stroke I could see the back side. Should I proceed as before, in your wizened opinions? Looks like 2 screwed valves facing the back of the block (exhaust?) and I was doing some welding without even knowing it. Another new skill! lol but seriously…duck…
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aztoytec said:
I would run it and see what happens. You have nothing more to loose
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I’m leaning that way. I didn’t have any noticeable issues before the belt issue so unless the valve massacre happened right at that moment, I think it’ll behave the same. Seems like I definitely need to start searching for some replacement parts soon though. Need the gubmint to start paying me again first.
 
aztoytec said:
I would run it and see what happens. You have nothing more to loose
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Like what he said, run it. Go from there, if all is ok and on the up and up you could test it later maybe run some cleaner etc.
 
vipergrhd said:
Like what he said, run it. Go from there, if all is ok and on the up and up you could test it later maybe run some cleaner etc.
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Yeah I heard about walnut dust sprayers. Seemed intriguing. Otherwise, I’d like to fix rather than replace eventually. Seems less wasteful. I was just riding high and now this is a bit of a bummer. Makes sense why my leak test on #1 was so horrible though.

Just need to add the plug and coil, air intake, cover, and coolant in the morning. I’ll start it and let it idle to see what happens.
 
Have you fired it up after putting it back together? I usually run it for a few seconds just to make sure, I would suggest to hold off the coolant until you verified everything is good you could always flush it once you verified the engine is doing well. Just my 2 pennies.
 
vipergrhd said:
Have you fired it up after putting it back together? I usually run it for a few seconds just to make sure, I would suggest to hold off the coolant until you verified everything is good you could always flush it once you verified the engine is doing well. Just my 2 pennies.
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Oh no I didn’t think of that. Good idea. Why waste the coolant if there’s a problem evident in the first few seconds running. It won’t get warm enough to need it. I still need to plug in cylinder 1 and the air intake assembly. Got frustrated and it was late.
 
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Repost:
"Piston top:
If" this is a pocket of erosion in top surface of piston and not illusion. The piston would need replacing. As it will very likely fail in time. Replace timing belt, see if runs okay. Drive as you look for good used engine, may be good idea."
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The carbon, pits in cylinder wall and piston top and valves. IMHO: Most conditions in #1 cylinder, developed over time. From issue in that cyclinded.

We now see what looks like interference on piston top. I have warn, that under the right condition, interference can happen. It looks like you "may" have those condition. It "may" be carbon on valve(s), close the gap between piston & valves enough. Or issues with valve gap adjustment, valve spring, etc.

But angle, spacing, positions and number of hits on piston. Doesn't look quite right for valve interference. It's like some metal was bouncing around in the cylinder.

I've seen, where a foreign object. Have fallon in cylinder(s). Which enter either through spark plug port or intake port when intake manifold pulled off.
Most common is sand. Which causes cylinder wall (vertical lines) & ring damage.
I've also seen, 10 mm bolt accidently dropped in.
Also, Spark plug blow out. Pieces of spark plug, can drop in.
Then fix for a blown out spark plug; Time-Sert in-situ drop in metal.

IMG_8679.webp


To get better idea of valve condition. The valve needs to be open, so seat can studied with borescope. Valve steam may have been bent. If so, valve(s) will not seal, even if seat okay. So it may run worse than it did.

Short block is trash, piston damaged, valves may also be damage. IMHO, this is not a rebuildable engine.

What are we looking at here?
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FWIW:
Intake valve are the larger along top row
Exhaust valves are smaller lower/outer side of block.
2UZ 4Runner 126.webp
 
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2001LC said:
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Repost:
"Piston top:
If" this is a pocket of erosion in top surface of piston and not illusion. The piston would need replacing. As it will very likely fail in time. Replace timing belt, see if runs okay. Drive as you look for good used engine, may be good idea."
_______________________________________________________________________________________________________

The carbon, pits in cylinder wall and piston top and valves. IMHO: Most conditions in 1 cylinder, developed over time. From issue in that cyclinded.

We now see what looks like interference on piston top. I have warn, that under the right condition, interference can happen. It looks like you "may" have those condition. It "may" be carbon on valve(s), close the gap between piston & valves enough. Or issues with valve gap adjustment, valve spring, etc.

But angle, spacing, positions and number of hits on piston. Doesn't look quite right for valve interference. It's like some metal was bouncing around in the cylinder.

I've seen, where a foreign object. Have fallon in cylinder(s). Which enter either through spark plug port or intake port when intake manifold pulled off.
Most common is sand. Which causes cylinder wall (vertical lines) & ring damage.
I've also seen, 10 mm bolt accidently dropped in.
Also, Spark plug blow out. Pieces of spark plug, can drop in.
Then fix for a blown out spark plug; Time-Sert in-situ drop in metal.

View attachment 4009453

To get better idea of valve condition. The valve needs to be open, so seat can studied with borescope. Valve steam may have been bent. If so, valve(s) will not seal, even if seat okay. So it may run worse than it did.

Short block is trash, piston damaged, valves may also be damage. IMHO, this is not a rebuildable engine.

What are we looking at here?
View attachment 4009457

FWIW:
Exhaust valves are smaller lower/outer side of block.
Intake valve are the larger along top row
View attachment 4009465
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No sorry to cause confusion. Those marks you indicated near the center, the sharp lines, were from my scope. I was trying to see if it was water drop or soft and couldn’t get angled right, so I pressed against piston head to bend the scope a little more. Those were not there before that. The ones near the edge were there before. It may be as you say. I just buttoned it all up and ran without coolant for a couple minutes to see. It ran fine with a little smoke. Then added coolant and burped. It runs as advertised with no issues. More smoke this time, but it subsided at the end. I’m going to test drive soon.

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Also, that is the dot indicating left hand side next to LH letters you pointed to. The marks on it look like welded on speckles raised from the surface like the middle spot. I was showing it is raised up not pitted in.

I think both damaged valves are exhaust toward outside of block pointing to exhaust manifold.
 
Cool.
Make sure to check under radiator cap for air. After 8 hour cool down. Do this in the AM before sun-up, is best/coolest time of day. Best parked with front end higher than rear, places radiator cap as high point.
 
JungleMunkee said:
I did. Unfortunately, the test drive revealed a leaking thermostat housing which made my drive belt slip off… never ending man. Luckily, no issues with the rest.
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I told you, now just fix the leak and you should be back on the road again.
 
Toyota's made between 90's and mid 2000's can take a lot of abuse! The only vehicles that survive in all 3rd world nations! Some Suzuki Vitara's, Defenders, early Montero's and Nissan Patrols should also be added to the list!
 
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