Broken Timing Belt Confirmed (1 Viewer)
- Thread starter jgray
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hoser
SILVER Star
I dunno, to me it is not too surprising jgray didn't damage his valves/pistons. I'm guessing interference only occurs when a piston is at/near top dead center at the same time a camshaft lobe is at/near its maximum lift. If the timing belt breaks, I would imagine the cam would likely stop somewhere away from maximum lift of any one lobe since that is where the valve springs would have the most compression.
I could be completely off though. Experts, please chime in.
I could be completely off though. Experts, please chime in.
Which should have been the case when Dan manually turned his cam. At least two of the jugs under that cam should have been TDC.
hoser
SILVER Star
Why would two jugs be at TDC? Aren't there points in time where no piston is at TDC?
APKhaos
Unfixing the unfixable
By definition, Top Dead Center is the point at which two cylinders on each bank are at the top of their stroke.
Also by definition, an interference engine at TDC means any valve that is fully extended at that point due to lost cam timing will be hit by the crown of the piston at top of stroke.
To do a tbelt job you first set the crank to TDC before pulling the belt.
so for us in the 100k club ready for first change of belt; it is recommended to switch all (tensioner, bearings and water pump) no matter how good they look???
Yes. It's probably just over three bills in OE parts from Lowe.
hoser
SILVER Star
Thanks OregonLC & APKhaos... got it.
2000UJZ, Mine too at a little over a hundred twenty. Looked damn near brand new. Went at it with a magnifying glass and still couldn't find much in the way of cracking. Must be all this California Sunshine! And I guess that's also because my wife drives the 100 and I cruise in the 62.
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The other big thing I take from this is the need to decrease the service interval if exposed to copious mud or water. Evidentially the timing belt covers are really just dust covers.
Muddy Bean
Breaking something or fixing something
My sentiments exactly. His air box water line marks are telling. Someone correct me on this: am I wrong in stating that the LC's water wading depth is rated at 3 feet? I assume the tensioner pulleys are above that mark? In other words, as capable as the LC is in extreme duty use, there are limits to dunking something with so many mechanicals and electronics in muddy water. The guys on YouTube driving around with their roll cages completely under water and only their snorkel tip sticking out are driving stripped out rigs. If a minor windshield leak can destroy an expensive ECU on our trucks (don't ask me how I know this) then over dunkage is certainly cause for concern snorkel or no snorkel. I for one am going to extend my diff breather tubes because I've had water intrusion in the past in my previous yotas during water crossings. Again, are they set to a length that is beyond the 3 feet that the LC is rated for? Not an expert. Just musing concerning his tensioner failure.
TSB states pink LLC is interchangeable with red LLC, starting in 2002. This not the same as SLLC antifreeze, which I have no idea what color it is, maybe orange.
This is not a TSB, but from Toyota and it does say SLLC is compatible with LLC red: http://www.toyota.com/owners/web/pa...oogle|AfterSales_Part_Types|_+toyota_+coolant
Oh no some with pink, some orange. Well, lets not tell the 80 guy's they never let us live it down.
Based on this info it is clear that the two are compatible.
At this time Toyota does not use a coolant that is orange, that would be along the lines of GM's Dexcool.
There is a blue coolant specifically for the Scion FRS (Subaru powerplant).
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I don't think that has a huge role in longevity. I may be the 1% here, but my timing belt was done at 70K, and 200K (180 on OD, tire size correction). I've had my front end deep in nasty water, and at one point sunk up to the hood in mud and ice. I left the engine running and it pulled the mud and water into the belts, pulleys, etc. my timing belt looked very nasty, but it was not cracked, nor missing any teeth.
What I think is happening, is the quality of our replacement parts going down. Our steering racks aren't lasting, our timing belts are failing much faster, I've found that as I replace the OEM original items with new "OEM" items they just don't hold up. I am in steering rack #5, the OEM rack lasted 12 years, in the past 2 years I've soared through replacements (all OEM new). Seems to be a trend with timing belt breakages and frayed belts prematurely.
I could be totally of my game right now, I may be wrong. It just seems like a lot of cruisers having the same issues at the same mileage with the same OEM replacement parts under the same conditions.
Trunk Monkey
Moderator
I posed the interference question to my friend that trains the Toyota techs in the West. His response "yes, it's interference, but I have not seen bent valves on the non-vvti engines when a belt breaks. The vvti engines will bend valves with just a tooth or two out of time".
I wonder if the nature of the variable timing allows them to run a higher cam profile where static timed 2UZs have to run a more moderate profile?
Further, unless I'm interpreting Dan's post incorrectly, he turned the cam 360 without it touching the piston. This and 'interference' don't jive.
Further, unless I'm interpreting Dan's post incorrectly, he turned the cam 360 without it touching the piston. This and 'interference' don't jive.
2001LC
SILVER Star
Is 360 deg rotation of cam enough to fully extend all values on one side or do we need 720 deg?
You only need to turn the cam 360 degrees. To get 360 on the cam, the crank must turn 720. In this case the crank is static.
2001LC
SILVER Star
I noticed in the picture of the heads it looks like two cams would fit into each head. https://forum.ih8mud.com/showpost.php?p=8863345&postcount=51
I've not worked on modern heads with cams in them so I'm unclear on the inner workings. Can you clear up the mechanics of why & how these dual cam heads open valves and what valves for me?
I've not worked on modern heads with cams in them so I'm unclear on the inner workings. Can you clear up the mechanics of why & how these dual cam heads open valves and what valves for me?
The 2UZ is a 32V DOHC with both cams (per side) gear driven off a single toothed pulley. One cam (toward the center) is intake, the other is exhaust. There are no adjustable rockers; the lobes directly push on buckets on top of the valve stems.
