hoosier58

I've been reading posts (and watching youtubes) to gain confidence for doing my SC3 timing belt. I've never done one on a DOHC engine. I plan to do crank and cam seals while I'm in there.

Any tips from those of you who have done it before? I'm doing it without a service manual. I can't justify buying one when I'm getting ready to sell the car.

My car's a 94, so it is non interference. That relieves me some, but I still don't want to have to take it apart more than once

EDIT: Sorry about starting this thread in the wrong place.

Ali SC3

iTrader: (10)

you should get a service manual, you can probably get one online look for 95 supra manual and it has sections in there for the non turbo motor.

myLEXsc400

What does "non interference" mean? If the timing belt snaps on our cars, does it bend the valves and hurt the motor, or does it have a safety like the 1UZ where nothing will happen and you just put a new belt on?

hoosier58

Only the VVT-i are interference (valves hit pistons and bend).

Ali SC3

iTrader: (10)

non inteference means that the valves and pistons never occupy the same space, so they won't hit if the belt snaps.
all non vvti 2jzge and 2jzgte are non inteference. on vvti they became inteference.

on a 1uz, they were non inteference in the early years 92-94, then there were a couple mid years 95-97 of inteference and raised compression even on the non vvti, and then the later vvti years 98+ are all inteference.
So on a 1uz its a common misconception that all non vvti are not interference, and if you go off that info and never change the timing belt, when it snaps 92-94 can just slap on a new belt, but 95-97 the motor/head will take damage and it will require much more work.
Change your belts!! It's not that hard on either engine.

hoosier58

I'd like to add that 'non interference' wasn't something engineered in for the safety of the valves. It was just that the piston/crank system and cam/valve system didn't cross the plane of the cylinder bore top. A milled head, for high compression, could, for example, change that.

Honda, with VTEC, then Toyota, with VVT-i, varied the timing of the intake valves. They aren't tied to the camshaft in the same way as earlier designs. If your timing belt breaks, the cam is not going to pull the intake valves clear of the cylinder bore top (and piston travel) the way a non-varied, set ratio, valve timing would.

Though I'm no engineering expert, I picture it a little like a CVT auto transmission. The drive gears of the intake valve system travels along a cone, instead of a set gear to gear ratio. The cone has no way to pull the intake valves back up, out of the way of the piston.

hoosier58

Thanks, Ali!

SC3coupe

iTrader: (4)

Hardest part should be the crank pulley and timing gear removal
But its been done on the car since factory it would be less difficult to remove

Ali SC3

iTrader: (10)

starter trick to crack crank pulley bolt loose before you take stuff off the engine that would keep you from doing that.

tjmhillz

iTrader: (6)

^^agreed. I done a few timing belts on these motors and the Starter trick works every time. Just be careful when doing it. because if the breaker bar isn't on tight enough it will fly off. Other than that like Ali mentioned make sure you change the belts and tensioners since you will have it off.

myLEXsc400

my sc400 is a 1996, and when I took it to the shop and got the belt changed, my mechanic told me that it was a non-interference motor (just not in those terms). Basically he said that if the belt snapped, everything would be ok.

Ali SC3

iTrader: (10)

yeah its a bit dangerous but the easiest way to do it. I hate it when people pull motors without doing it first, If the motor is coming out and I will need to take it off I just brake it first, tighten the bolt back up by hand and set it to TDC, and then yank it out... or you will be using a chain or strap or wedging stuff with 8 foot breakers all day long.

Yeah as I said its a common misconception thats why I mentioned it I saw you were in those year ranges and saying they were non-inteference.
I have been told dozens of different things on the subject by various mechanics and even toyota techs, they just look up what in the general manual, and yes its listed as non-inteference in aftermarket timing belt manuals, but I have heard of 96 1uz motors with bent valves from when the timing belt goes, there was even one for sale here locally they tried to just change the belt but the motor never ran properly again (not surprising).

Also, the fact that they increased the compression in 95 on the 1uz, and changed the rods along with some other small things, would make one think the head was shaved down to get that compression and would likely be inteference. I don't know 100%, but most people who swear by it from experience that their motor took no damage are almost always talking about 92-94 motors, which are the ones that can take boost the best.
Most people do not realize the 95-97 1uz's are different, there are 3 revisions of the 1uz used on the sc400, 2 of them were non-vvti.

straight from wiki
http://en.wikipedia.org/wiki/Toyota_UZ_engine
In its standard, original trim with 10:1 compression, power output is 191 kW (256 hp), torque of 353 N·m (260 lb·ft).
The engine was slightly revised in 1995 with lighter connecting rods and pistons and an increased compression ratio to 10.4:1 resulting in peak power of 195 kW (261 hp) and torque of 363 N·m (268 lb·ft).
In 1997, Toyota's VVT-i variable valve timing technology was introduced along with a further compression ratio increase to 10.5:1,[1] bumping power and torque to 216 kW (290 hp) and 407 N·m (300 lb·ft). In the GS400 application, output was rated at 300 hp and 310 lb·ft of torque.

tjmhillz

iTrader: (6)

These vids helped me out the first time I ever did timing belts on these cars.

hoosier58

I already watched those. They helped give me confidence. Thanks though.
I also read a Supra post by a guy that replaced his broken timing belt on the side of the road ---- brake parts cleaner, white out, a breaker bar and 19mm socket were all he had to buy to supplement the tools he already carried.. He wasn't doing seals or water pump though, and reused his tensioner until he could get the car home and do the job again.

I looked for a 95 Supra manual download, but what I found was a scam to get me to download a malware download manager.
Can anyone direct me to a safe download site?

hoosier58

I found a website that looks official Toyota. Technical Service Information (TSI). If I open an account, I can pay by time periods (year and month ... and maybe day ... can't remember for sure, then access Lexus service manuals. I think for $15 I can have temporary access, and maybe print the pages I'll need to do the job. Has anyone used TSI?