i believe the engine became interference in 96 for the SC's and 95 for the LS due to the new cams they put in with a higher lift.

 

750 dollars, a new belt and a new tensioner later the car runs better than before.

I think there was a problem with the tensioner. the hesitation and the sluggishness the car had been experiencing recently is gone now.

95 Sc400's are definately non-interference engines.

 

back from the dead......
my car has just hit 114,000 and theres no service records since 45k, so i know i should have it done semi soon. its a 93 sc400 so its non-interference, meaning i wont bend valves if it does break? and where is it located so i can check to see if theres a sticker for if it was done. also, is the tensioner expensive and a bunch more to have put on?
please help,
thanks

 

Don't bother replacing the timing belt until it breaks.

Once it breaks,

replace the tensioner
replace (2) idlers
replace the water pump
replace the belt (obviously)

Thats it. Your valves will not be damaged due to timing belt failure.

I replaced all that stuff and my timing belt still broke 6 months later. Just wait until it breaks.

 

let us see some pics sounds pretty interesting

 

I don't want to start a new thread, and I searched resulting in 30+ pages of "Take it to a lexus dealer," "It's too difficult," "I like to post but I don't know how", but is there a write-up to changing timing belts on sc300, or replacing headgaskets?

 

I would have changed it myself except there is a few special tools needed..

The cam lock in place tool cost my mechanic 1600 dollars.

Maybe you could do the job without it, but it doubt it.

 

This is a good thread but i have a question. What is the diffrence between a Non interference engine and an interference on, and I'm not looking for the obvious that non interference is safer when a timing belt break. I am looking for the more technical explaination if anyone has it.

 

An interference engine has no room for error when it comes to the valves in the cylinder head that are opening due to the camshafts and the pistons swinging on the rods connected to the crankshaft.

If your timing belt breaks your cams no longer turn. (the camshafts use the timingbelt to direct force from the crankshaft to make them turn). If the cam shaft no longer spins this means the valves which are open stay open, because the crankshaft keeps turning a piston is on it's way up the cylinder to Top Dead Center. On an interference engine the piston smashes into the valves and bends them up. You need new valves and a new valve job, or a good cylinder head at this point.

Non-interference means that no matter how much you spin the bottom end of the motor while any of the valves are stuck at max lift, the pistons will not hit them.

 

An interference engine has no room for error when it comes to the valves in the cylinder head that are opening due to the camshafts and the pistons swinging on the rods connected to the crankshaft.

If your timing belt breaks your cams no longer turn. (the camshafts use the timingbelt to direct force from the crankshaft to make them turn). If the cam shaft no longer spins this means the valves which are open stay open, because the crankshaft keeps turning a piston is on it's way up the cylinder to Top Dead Center. On an interference engine the piston smashes into the valves and bends them up. You need new valves and a new valve job, or a good cylinder head at this point.

Non-interference means that no matter how much you spin the bottom end of the motor while any of the valves are stuck at max lift, the pistons will not hit them.

 

See this page, at Toyota Imports Forum / GB. a big Soarer page:
How good are the Timing belts on the V8 ?

 

I'm late to this conversation, but a couple of points:

1) Nothing you could have done at the track could have caused a properly installed timing belt to skip. It was obviously not installed correctly and if it was at a dealer, you need to go back to them and make sure they replace everything free of charge if it's less than 12K miles.

2) Your hesitation, given what you know about the timing belt, was most likely caused because you're belt had *already* slipped a tooth or two on one or more sprockets. It's running better now because the timing belt is actually aligned correctly when it wasn't before the final slippage and shredding occured.

 

That tool isn't even close to $1600. Was it the dealer that told you that?

Secondly, you can do it with the tool. Either the belt-wrap trick using the old timing belt or you can do what I do on every other car and use the a heavy duty belt vice. They sell them pretty much everywhere. I bought mine at Lowes. I used it to change the timing belt on my 300zx which is way tougher than the SC400 pus on the z if it were to slip, you'd mash your valves.

 

That is what I knew of my 92 SC. I asked the service manager of Kearny mesa Lexus, when I was getting the service history of my 98SC, and he said after 97, ALL Lexus engines are intereference engines.

 

Sorka you shed some good light on the matter. The point you made about the belt already had sliped really hit home.

Last weekend I changed the serpentine belt tensioner because I cold move the pulley with my hand. Replaced the belt too. I noticed the hesitation at take off improve some more. I had rednecks work on my car the first time, their shop is going out of business because the owner Jeff became a Scientologist or some crap. In most cases, I work on the car myself. I didn't this time because my dad convinced me not to. We were told that the job required the cam locator tool and that I couldn't handle the job, whatever, whatever.

Anyway...I had to remove the alternator and plastic covers in order to replace the belt tensioner and I noticed that I wasn't that far away from doing the timing belt. I could see the aluminum peices and the water pump and ac compressor were in the way. I know I could have handled the job myself, but it would have been nice to have a garage and not work in the alley...

Thanks for the reply.