I’ve learned a lot of good information reading Club Lexus forums so maybe I can now share something with someone else who’s planning to replace a timing belt on his / her SC430. You must know that the excellent post on this forum from Sep. 2007 by Pearlpower was my inspiration to replacing my SC’s timing belt – naturally all the warnings and disclaimers therein apply so I won’t repeat them. I used the 430 service manual as well, and as I went through the process I took some notes that I hope will help if you’re thinking about doing this yourself. Like the Pearlpower post this is by no means a complete description of the process, just some observations from my viewpoint that may help you as you think about doing the job.
My SC430 just turned 38,000 miles but since it’s an ‘02, I reasoned that the engine was probably at risk on the basis of time in service, not the mileage. So I bought the timing belt ($40) and serpentine belt ($36) thinking that I would make the call on the water pump, idlers and tensioner when I got into it. I normally try to avoid SSTs but I had read enough discussion about the dreaded crank damper pulley bolt that I bought a Schley Products #64300 damper pulley holder for Lexus and Toyota ($65 incl. tax and shipping from Amazon).
As to my qualifications I am a graduate mechanical engineer (by no stretch a journeyman automotive mechanic) with no experience in engine work on Toyota products. In most respects I approached this project as being fairly green and moved forward carefully with no expectation of completing the job in any set amount of time. Here are some thoughts from my experience from doing the job a few days ago:
1. If you have the Lexus repair manual for this operation you can use the stepwise instructions as a checklist. There isn’t a lot of difficult work involved in this job but there are many individual steps. It would be a shame to miss something.
2. Besides the Pearlpower-recommended tool list I used a 3/8” air ratchet. This saved some effort in removing and installing the under engine cover and for running up a number of the fasteners before final tightening. I also used a couple of 25 inch breaker bars and a torque wrench. I didn't use any impact tools.
3. To access the parts for removal I needed to raise the car about 4”. I’m not a big guy so I have to balance the amount of space needed underneath versus the amount of reach I can get while leaning down into the engine room. I use ramps that are built up from layered 2 x 12 wood scraps. I just drive up on them, set the parking brake and use rear wheel chocks.
4. You’ll be removing a number of parts. You should designate a space where you can lay them out in exact order removed with their respective fasteners. Keep children and dogs out.
5. I chose to drain the cooling system partially and remove the radiator. You only have to drain it down from the radiator drain valve and then disconnect the two coolant hoses at the engine. My experience was that you won’t lose much more liquid when disconnecting the bypass hose as the left side timing belt cover #3 comes off. The working space gained from removing the radiator and fan assembly was worth it to me. You WILL want a couple of plugs for those oil cooler hoses if you do it this way.
6. You don’t need to completely remove the PS vane pump, alternator or AC compressor. The alternator and compressor can be unbolted and moved slightly aside / downward with the electrical connections intact. Removing the drive pulley from the PS pump is enough to get access to fasteners behind. In my opinion one of the more difficult parts of the job was unbolting the AC compressor because of the difficult access to bolts.
7. Removing the crank pulley bolt – I used the Schley Products tool mentioned earlier, a 22mm 6-point socket and two 25” breaker bars to hold the pulley and loosen the bolt. I was able to do this in one try without breaking a sweat. I’d estimate it took about 100 lb pull on the breaker bars to dislodge the bolt. As a practical matter I used the same estimated torque to re-install it since my torque wrench doesn’t go to 180 lb-ft. Since it was super handy for rotating the crank later (and I have two other cars that can use it) I would buy that Schley tool again.
8. I inspected the water pump, idlers and tensioner in detail and decided NOT to replace any of them on the basis of condition and the low mileage on the engine. There were no leaks and all the bearings were smooth. My labor is free so if I need to go back in to do some work later that’s OK. You may want to adopt a different philosophy and change all that stuff out while you’re in there – at retail the additional parts should be about $250.
9. Be sure to line up the timing marks BEFORE you remove the old belt. Then the Lexus manual recommends positioning the crank at about 50 degrees BTDC to avoid potential damage to the valves from camshaft springback as the old belt is removed. I worked alone and I thought this was somewhat difficult to do since I had no way to know which way the camshafts would try to turn. For this operation AND putting on the new belt I think it might go better if you have help positioning the camshaft pulleys. You can make some slight adjustments with the cover bolts on the ends of the crankshaft assemblies but they aren’t tight enough (11 lb-ft) to provide much counter-clockwise adjustment. Until the tensioner is re-installed there is a chance that the belt will be loose enough for the camshaft pulleys to jump a tooth or more – watch to be sure it doesn’t happen or you will need to start over positioning the belt.
10. Timing marks on belt – they are used for putting the new belt on initially so that you get the right number of teeth between the rotating components. I put the belt on with the crank at about 50 degrees BTDC and it worked fine. You start with the belt on the crank and work around the idler, then the left cam and on to the right. As Pearlpower notes any method of tooth alignment should work. What’s important is to very carefully check to be sure all the timing marks are absolutely lined up when at TDC. After you install the tensioner and when you are satisfied everything is lined up THEN you turn the crankshaft slowly two turns clockwise to check for valve interference. Re-check the timing marks on the crank and camshaft pulleys at this point. The marks on the belt now will be useless unless you restart the process. By the way, my damper pulley was a close slip fit on the crank so I was able to slide it on with the timing gear cover #1 and more precisely check the TDC mark.
11. Pay attention to torque specs as you button everything up in reverse order. As you near the end, you should leave the under engine cover off until you are sure you’re good to go.
12. Statistics: I took about 7 hours to do the work, spread out over two days working alone in my garage. Consumables: 6 shop towels, 8 pair nitrile gloves, 1 pr cheap cotton gloves, two Sam’s Club lawn waste bags (my “creeper”). The savings for performing this work was about $700 to $1000 depending upon whether I used an independent garage or the Lexus dealer.
Well, there’s another guy’s take on the process. I hope the lengthy post is helpful to someone. I think the next thing I need to work on is rear brakes. I plan to keep the car pretty much stock. Anyone with recent SC430 brake experience have any thoughts or wisdom to share?
In response to tfeni52355, the timing belt I removed looked and felt fine, which is in line with what you had heard. The serpentine belt was definitely cracked and dried a bit so I figured in the worst case the timing belt might be deteriorated to some degree also. Just sounded like a good idea and I had the time to do it. And maybe I do sleep a little better now.
Thank you for posting this DIY with real instructions!! Woulld it safe to assume that this procedure can be used on the 1UZ-FE V8 GS400 vvti motor? This should be a sticky!!!
"Distant thunder, cold as stone,
a V8 screams down from its throne.
One by one, each car succumbs,
Something wicked this way comes."
1999 GS400 Black Onyx w/black interior and bone stock except for the intake so far....
it's interesting how the sc430 manual wants you to be at 50* btdc and the ls430 manual wants you to be at 50* atdc to set timing. It's easier 50* atdc because there's T marks on the cam overs (can be seen in pictures next to the | mark)
edit: i think it's because you get to take off the cams on the sc430's manual, which means you could just leave it at tdc
Fitting a body kit and stretched tires on cars is like fitting a dress and high heels on women.
In my experience an estimated 50 degrees BTDC worked OK for installing the belt on SC. The camshafts seemed unwieldy at that position also, but they were impossible to hold at TDC (by myself). So I used the marks on the belt to align with the marks on the pulleys at about 50 degrees BTDC then rotated to TDC to check all the marks together.
Werd. I made this error where i insisted on setting the timing at tdc even though left cam would shoot back by about 45* once the belt is off. I guess when I moved the cam back, I was off by one tooth. I'm going to set the timing at 50* atdc just to be safe. You can also rotate the crankshaft counter-clockwise via the crank bolt (not the pulley) to check the timing at tdc, and then manually turn the engine two cycles to make sure nothing is hitting anything.
It is also imperative that you set the left cam 1/2 teeth and the right cam 1 teeth to the right of the timing mark of your choice (clockwise). When you put the tensioner back on, the belt will move back by that much. You should not be moving the crank to adjust timing at all at this point, and only move it after the belt is on both cams with the tensioner on.
Fitting a body kit and stretched tires on cars is like fitting a dress and high heels on women.
Absolutely - as the original post suggests, it doesn't really matter how you get there but all the timing marks need to line up at TDC (compression), and you need to be able to successfully rotate the engine by hand. It's easy to underestimate the amount of springback those valves can exert so if 50 degrees ATDC works well for you then so much the better. I was just scared enough that I followed the manual as precisely as possible. I believe that if I hadn't been holding the belt securely enough during the process that both cams easily could have jumped a tooth or more. I thought that the marks on the belt were pretty useful to see when that's happening.