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timing belt slipped

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Old 07-09-14, 10:20 AM
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dgb744
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Default timing belt slipped

My 92 SC400 suddenly stopped. I attempted to start it but it made a clanking or knocking sound.
I took it to a mechanic and he told me the timing belt had slipped as a result of the water pump freezing.
He indicated that I should have heard the impending seizure of the water pump.

I think possibly a timing belt tensioner bearing or idler bearing when bad and caused this however I did not hear any impending failure.

Has anyone experienced this. Originally my belt was replaced some 30,000 miles ago and we put a new tensioner on it.

I wonder what the total repair will be. I am expecting intake valve damage.
What are the recommeded parts, costs associated with getting her back on the road.
Should I just part the car out?

HELP
Old 07-09-14, 08:20 PM
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Kris9884
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Yep part it out, can I get your headlights?

JK, if it comes down to internal damage you are far better off getting a replacement engine, even a used motor from salvage r something.
Old 07-09-14, 08:35 PM
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Rhoderman
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Knocking would be good. Clanking bad.
I believe yours is a non interference engine, so your valves should not have struck the pistons.

A new timing belt kit should run you a few hundred if you DIY. There are lots of other things to do "while you're in there" that will drive the cost up.

Does the timing belt run the WP on a SC400? The 300 is run from the accessory drive belt, and therefore not related.
Old 07-09-14, 09:39 PM
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SC400slide
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The 1UZ is a non-interference engine. Once you get to VVT-i, thats trouble when timing belts break...
Old 07-14-14, 07:48 AM
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dgb744
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UPDATE: the waterpump seized and twisted causing the belt to slip while driving at 45mph.
The real question was did the valves hit the piston.
My engine was carboned, I ordered a borescope and all pistons showed no metalic signs of valves hitting. It is a interference engine. I got lucky, replaced waterpump-belt-cam and crank seals-installing new rotor and cap (2)-change oil.
This is at a respectable shop in my area and I suspect the bill to be around $1200.

Because this car is a garage kept vehicle-has new tires-I decided to take a chance and fix her. I will be thrilled once again to drive her. I suspect I will put 30K miles on her and sell her. I am open to selling her outright for $4,500.
Old 07-14-14, 12:10 PM
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Ali SC3
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your year is non-inteference. this is not a big deal just take the old belt off and do a timing belt job with waterpump. the valves cannot hit the pistons on the 92-94 1uzfe unless the heads have been resurfaced a fair number of times in a row, which no one really does that many times. you did a completely unnecessary test, and honestly they could have just done an easy compression test to see what was going on if valves were leaking or not. that is a high price for a timing belt job w/ waterpump on the v8 even, but should fix the issue.
Old 07-15-14, 05:47 AM
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dgb744
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AliSC3, I spent several hours researching whether my engine is non interference or not. On this site it has threads that showed referenced to non interference and several refer to it being interference. I called Lexus and talked to mechanics, I called local Toyota and Lexus mechanics which all four told me if it were a SC300 no worry but mine was a Interference motor, SC400-92 thru 95.
In order to do a compression check I had to replace the water pump and timing belt. That costs money. The one check you mention was un-necessary is borescope the pistons. That confirmed that I had no contact and this is the REAL ANSWER I NEEDED.
If valves had contacted the pistons I possibly would have JUNKED the vehicle, I go and pick the car up today. New cap and rotors, oil changed etc, oil leaks hopefully corrected.
Old 07-15-14, 11:27 AM
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Ali SC3
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you can call up a bunch of different dealerships and you will get a bunch of different answers, mainly whatever the head tech there thinks. I have heard both from dealers so you cant trust that source of info, they are wrong a bunch of the time they just care about getting you to change it, but I know that the motor is non- inteference.
alot of times they just look up the gates info which is known to be wrong on plenty of toyota models, this is very common the only source you can trust is original manuals and experience the aftermarket and dealers are not well versed in this stuff at all. they do know how to change one pretty well though, after all that is all they are concerned with not taking risk and saying its non inteference when it turns out it might be for all they really know.

many people have snapped belts and have been just fine on 92-94 motors. 95+ is a different story there was a slight bump in compression and that potentially makes it inteference (arguable still in these year ranges eveyone has a different opinion). VVTI is most definitely inteference and that is not been debatable even.

Even a 2uz non-vvti is non-inteference (vvti became inteference). this is commonly listed as an inteference motor, but many people have thrown a belt back on after the belt letting go and running just fine. If it was a vvti it would be valve crunch time.

Most everyone would have junked the vehicle if it was inteference, but the reason people go so long on these without changing it and letting it break like what happened in your case, is because they are not inteference.
Alot of people also make the mistake of thinking their 95 is non-inteference like the 92-94 and those people end up with needing new cylinder heads basically or a bunch of work done when it lets go.
You see why its safer to just tell everyone they are inteference now? you also see how that causes extra work for those who are actually non inteference because they actually have much less to worry about.

what I was trying to tell you is that you get different answers also because the 95-97 non vvti versions are inteference, and techs do not realize there were 2 generations of basically the same 1uz sc400 motor, so once they find out its inteference they just brand all of them as that, but 92-94 are NON-INTEFERENCE.

You did not get lucky and the test was completely unecessary, ok on the part that you cant do a compression test without the belt, ok got me on that one didnt think that far, but really the waterpump was frozen and the belt was broken so those are things you have to fix anyways. A baro test is wildly unecessary on this type of motor if you had just come and asked instead. unforunately over time alot of us enthusiasts have learned that we know more than the toyota and lexus techs do about these cars. to them its just another car, to us its much more involved and specifics of year ranges, etc... In fact when I do a internet search (and I have) I come up with most places saying it is non-inteference, and a few places specifically mentioning that only 95+ is inteference.

but if you had an inteference motor let go at 3000+rpm's and not damage a single of the many many valves you would be the luckiest person on earth and should start buying lotto tickets asap. If you really believe you got that lucky then I will stop with explaining what really happened I guess.

http://us.lexusownersclub.com/forums...-interference/
http://us.lexusownersclub.com/forums...-interference/

right in this one post #2
http://us.lexusownersclub.com/forums...erence-engine/
"My timing belt on my 92 SC400 broke last month. I didn't take it to a specialty shop, but I told them what I was told (from this forum) that the 1UZ-FE was a non-interference motor. Anyway, the timing belt was replaced along with my water pump. Car started up with no problems. They didn't check the compression on the cylinders though. They did tell me their manual shows the 1UZ-FE as an interference motor"
This thread talks about the 95+ also
http://us.lexusownersclub.com/forums...-interference/
post #7
"Sorry Guys, this looks an awful lot like the infamous Gates (Tire &) Rubber document in circulation that contains potentially catastrophic, incorrect information. As has been pointed out, it is not an official Toyota document, for the reasons previously stated.

As far as specifics, I can only comment on 1UZFE, LS400, 1995 1/2 & newer. Lexus increased the compression ratio a couple of tenths in mid '95, hence the 1UZFE became an interference engine, I absolutely guarantee it. Been there, done that. The unfortunate part about this is that everyone thinks that ALL 1UZFE engines are non-interference, which is NOT the case.

Prior to the change (small compression ratio increase) in mid '95, 1UZFE was a non-interference engine.

Lexus do just about everything right, but they should be flogged with a wet noodle for not re-assigning a new series number to the motor. They should also be called bad names for their choice of location of the starter as well as the whole Power Steering Solenoid Screen/Filter mess.

Of course, all VVTI engines are interference.

Rather than argue about it, if a person is down to their last 5 or 10,000 miles before the required T/B belt change, just change it, don't chance it. That whole "sleeping at night thing"...."
If you cannot digest that there are 2 non-vvti versions of the 1uz, a 92-94 one whicn is non-inteference and a 95+ that is inteference, then go ahead and keep thinking your 1992 is inteference (its not).
But the upside of assuming they are all inteference is that you change your belt in time (hopefully), but the downside is 92-94 end up doing much more work than necessary.

You should be happy to find out the 92-94 motors are the strongest version of the 1uzfe and can be modded the best, and are non-inteference.
If I was buying a sc400 it would be a 92-94 mainly for this reason as Its the one you want when you go to add boost or power adders.

Last edited by Ali SC3; 07-15-14 at 11:37 AM.
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