Air cleaner blew up, won't start now. Oh god...

[RND1]

It is an interference engine, the valves can contact the top of the pistons. Just because the timing belt fails, does not necessarily mean it will interfere, because the cams might land on the all closed position before the pistons hit the top of the stroke.

Do you have first hand knowledge of working on an LC with valve damage caused by a broken belt? I'm not saying it is not an interference engine, but what doesn't make sense is how several members here have experienced broken belts and no damage while not a single member has had a broken belt with damage (to my knowledge). It would be nice to put this question to rest.

 

[torfab]

I have worked on a few 2UZ's If you leave the cam in the wrong place and turn the engine over you can feel where a piston hits a valve. Here's an exerpt from the Toyota Manual:

(c) Turn the crankshaft pulley approx. 50° clockwise, and put
the timing mark of the crankshaft pulley in line with the
centers of the crankshaft pulley bolt and the idler pulley
bolt.
NOTICE:
If the timing belt is disengaged, having the crankshaft
pulley at the wrong angle can cause the piston head and
valve head to come into contact with each other when you
remove the camshaft timing pulley (step 19), causing damage.
So always set the crankshaft pulley at the correct
angle.

 

[adrenalinefjz80]

Torfab, you need to clarify if non-vvti.

 

[GDenver]

It is an interference engine, the valves can contact the top of the pistons. Just because the timing belt fails, does not necessarily mean it will interfere, because the cams might land on the all closed position before the pistons hit the top of the stroke.

I know first hand the non vvti motor is not an interference motor. The reason I decided to even attempt to replace the belt is because I was lucky enough to talk to a mechanic who had done 8 timing belt failures on this motor, and none had damage. Also in my further research, Toyota trained the dealers that the pre vvti motor is a NON interference motor.

 

[OregonLC]

 

[torfab]

I have felt Valve contact on a non-VVTI engine, and all reference material from Toyota's own techinfo.toyota.com points to it being an interference engine. I looked up a 2001 and a 2007, both which had the same "notice" about piston/valve contact. We treat them as interference engines, because that's what all the reference material points to.

If the manuals are wrong and the contact I felt was wrong, then you are right. I work on these engines all the time, and this is what my experience points to. My opinion is free, take it for what it's worth

 

[RND1]

I have felt Valve contact on a non-VVTI engine, and all reference material from Toyota's own techinfo.toyota.com points to it being an interference engine. I looked up a 2001 and a 2007, both which had the same "notice" about piston/valve contact. We treat them as interference engines, because that's what all the reference material points to.

If the manuals are wrong and the contact I felt was wrong, then you are right. I work on these engines all the time, and this is what my experience points to. My opinion is free, take it for what it's worth

It's great to have someone on here who actually works on these engines and knows them well. I understand all of the literature points to this being an interference engine, but it seems valve damage would be much more common from Mud members with broken belts. Have you or your shop ever had to do a top end rebuild as a result of a broken timing belt?

 

[Sandroad]

Not sure if this has come up already, but if the other head is in good shape, this may be a good engine to spin the crank on w/out a t-belt to check clearance. There may have been damage from the explosion on the other head, but spinning the good camshaft pulley might show that. I'll bet that test will show a freely spinning crank without interference if it's a non-VVT engine.

 

[torfab]

Good point! Time for a little testing!

No, our customers change their belt every 90k so nobody has broken one yet. The only time we had an engine meltdown it was because another shop performed 90k without replacing the water pump and it failed causing the engine to overheat. The engine wasn't salvageable, the intake had actually melted to the head. We tore the engine down and determined it was time for a replacement.

 

[RND1]

Thanks @torfab for responding. Guess the best advice remains - change the belts at 90K to be on the safe side even if we aren't 100% certain they're interference engines.

Back to OP, is your mechanic suggesting donor engine?

 

[LCtygrys]

Thanks @torfab for responding. Guess the best advice remains - change the belts at 90K to be on the safe side even if we aren't 100% certain they're interference engines.

Back to OP, is your mechanic suggesting donor engine?

My mechanic isn't sure yet about that. He's not dealt with this before but I have a great deal of confidence in his skill and his integrity. I also turned him on to this group to see what all of you have to say so some hive-mind benefit can be gleaned. Hi Gary I hope you made it ok!
I'm really curious about the end of the broken shaft and the cross grooves cut into it. Is this designed as a failure point to save the rest of the engine? I can't think of any other reason for that. Also does anyone else see any indications in the photos that suggest anything?
Have at it sleuths!

 

[tabraha]

Best of luck OP. You are the first to post up some actual decent images of carnage after having a t-belt let go. I guess we still don't know which came first, t-belt or engine issue to cause the shearing/belt popping. Keep posting info as you find out please!

Has your mechanic drained the oil and strained it yet for metal?

 

[LCtygrys]

Thanks everyone for your great input. It has been suggested that I look into a reman engine but with all the options online I must solicit the horde to offer some advice on a reputable engine seller. I found enginehaus but was promply steered away by the forum. Hopefully I don't need one but if so I need one quickly so I'd best be prepared.

 

[TXLX100]

No first hand experience, but jasper seems to be a huge and established engine shop. You might also try LKQ and greenleaf.

 

[torfab]

There are tons of engines out there, check on http://car-part.com/ for availability. Make sure it's not a rollover, and that the junk yard ran the engine up to temperature before it was pulled.

 

[jgray]

Just chiming in here as I am another case that had a broken timing belt. I was driving down the interstate at 70Mph when mine broke and I tried starting it multiple times prior to knowing it was a broken timing belt. It is extremely rare for this to happen and there isn't many documented cases of this happening but there are stories out there... Every case I have come across with broken timing belts for the 2UZ-FE suffered no additional damage. We pulled the heads on my engine and found no bent or broken valves or evidence of other damage... A new timing belt along with other normal replacement items and I was good to go... I have had no problems since and logged around 25,000 miles since mine broke...

 

[LCtygrys]

Just chiming in here as I am another case that had a broken timing belt. I was driving down the interstate at 70Mph when mine broke and I tried starting it multiple times prior to knowing it was a broken timing belt. It is extremely rare for this to happen and there isn't many documented cases of this happening but there are stories out there... Every case I have come across with broken timing belts for the 2UZ-FE suffered no additional damage. We pulled the heads on my engine and found no bent or broken valves or evidence of other damage... A new timing belt along with other normal replacement items and I was good to go... I have had no problems since and logged around 25,000 miles since mine broke...

Now that's the kind of post I like to read!

 

[OregonLC]

Is it possible for both cams to naturally come to rest with none of their valves extended? If not, I'm having a hard time figuring out how an operating engine with a broken belt wouldn't hit if it were interference. Torfab seems like a brilliant mechanic I'm just trying to wrap my tiny brain around the difference between the empirical evidence and his technical trial.

With a vehicle on the road, a broken belt would very quickly cause discontinuity between cam and crank sensors. This would shut fuel and spark but the engaged trans would continue to spin the engine. So if a valve was open how could it not be damaged?

 

[re_guderian]

Is it possible for both cams to naturally come to rest with none of their valves extended? If not, I'm having a hard time figuring out how an operating engine with a broken belt wouldn't hit if it were interference. Torfab seems like a brilliant mechanic I'm just trying to wrap my tiny brain around the difference between the empirical evidence and his technical trial.

With a vehicle on the road, a broken belt would very quickly cause discontinuity between cam and crank sensors. This would shut fuel and spark but the engaged trans would continue to spin the engine. So if a valve was open how could it not be damaged?

Seems like we've rehashed this, and again, I'm an idiot on the internet and not a master engine rebuilder, but once the belt breaks, what mechanism actually FORCES the valve to the full open position since the cam stops rotating with belt failure? Is the inertial load on the cam enough to overcome all the opposing spring pressures, or will the spring forces just cancel each other out and leave all the valves half open? Does it depend on how many additional revolutions the cam makes, and what position it ends up in? BTW, I suck a physics, too... Again, just armchair quarterbacking it here, but it sounds more like an intake valve stuck open, or the cam seized with an intake valve open to have cause the detonation in the intake manifold/air cleaner, and that seizure then sheared the sprocket/broke the belt.

 

[Trunk Monkey]

In the OP's case, I think something else caused the belt break. But, for the interference and bent valves, as I understand it, depends on where the belt breaks. It can drag over the cam, moving the valves, and causing the piston strike since it's now no longer in time.