SC300 Timing belt Replacement Instructions (1993 year)
Due to the complexities of the valve timing and internal engine clearances, these engines will most likely bend valves if the belt fails, or if the belt is installed incorrectly. For these reasons, I would recommend that you read through this information and the service manual description for this job very carefully before starting this repair. There are also differences between models on this platform that can impact the way certain components are removed.
General Information:
I decided to put this “how to change a timing belt on an SC300” information together because I found it difficult to find conclusive information on the internet.
My main concerns going into this were:
1. How difficult is it?
2. Do you really need to remove the radiator?
3. What are the most common problems encountered?
4. What special tools do you need?
Here are the answers:
1. Not too difficult with the correct knowledge and tools, (I’ve been working on cars for 33 years)
2. No you do not have to remove the radiator.
3. By far – the most difficult task is removing the crank pulley bolt. This is torqued to 239 ft/lbs, but you need almost twice that to get it off.
4. A ½” breaker bar (make sure it’s got a good guarantee because I broke my first one). A hardened 22mm socket. A 3ft length of pipe for the breaker bar (cheater). Some method to hold the crank pulley (24” chain wrench with a cut piece of old surpentine belt), or the Toyota/Lexus SST, or a home made tool (can provide a picture and specs upon request). A ½” torque wrench that goes to 250ft/lbs. The Lexus or Toyota repair manual or equivalent.
You really need to figure out when you want to replace your timing belt – the information for the older SC’s recommends changing it at 60K, and the information on the newer SC’s recommends 90K. I split the difference at 75K, which is conservative. My car was 16 years old at the time of the belt change.
Additionally you have to determine what you want to change while you’re “in there”. I suggest checking and replacing what needs to be replaced instead of doing it all, (cam seals, crank seal, water pump, etc.)
I don’t suggest removing the entire radiator. You can if you want to but it is completely unnecessary.
The crankshaft pulley (a.k.a. harmonic balancer) bolt can be a real problem to remove and I suggest that you make sure you are up to the challenge before you start. I managed to destroy my Crankshaft pulley because I was holding it from the outside with a 24” chain wrench (while protecting the pulley surface with a cut section of an old serpentine belt) and I spun the outer pulley from the inner core. This happened when I was trying to remove the Crankshaft pulley bolt using a ½” breaker bar and a section of pipe for leverage. Since I don’t have the Toyota SST (special service tool) I made my own out of a piece of angle iron. But that is a story for another day and I can provide a picture of the tool if requested and if you are local I could lend you the tool (central NJ). If you do trash your harmonic balancer, a new one cost about $475.00, used ones go for $75.00 to $125.00, and you can get an after-market one for $125.00 (that’s what I did).
Here are the instructions for the quick and easy to do the job:
1. Disconnect and remove the battery and the battery tray. I also disconnect the coil ignition wire just to make sure the car will not start.
2. Loosen four bolts on fan (while you still have tension for the serpentine belt) but don’t remove the bolts.
3. Remove the serpentine belt and then remove the four fan bolts and the fan.
4. Remove a pint of coolant from the radiator to get the level just below the top radiator hose.
5. Remove the two top bolts from the fan shroud.
6. Temporarily remove the top radiator hose from the radiator. Then bend the hose back and remove the radiator shroud, (this may take to people, and you may get some coolant coming out, so have a coffee can ready). The shroud has two small rubber bushings that hold the bottom in place, don’t loose them.
7. Reconnect the top radiator hose to the radiator and slide the clamp back into place. Protect the exposed portion of the radiator with a piece of cardboard cut to size and tape it into place. This will prevent damage to the radiator from tools.
8. Remove the bottom plastic cover from under the engine. (9 x 10mm bolts and 6 x 10mm screws)
9. Remove the top timing belt cover.
10. Remove the serpentine belt tensioner.
11. Remove the center timing belt cover.
11.a. Turn the crankshaft pulley bolt clockwise to align the timing marks on the cam and the crankshaft pulley in order to get the engine in the correct position for removing the timing belt. There are marks on each of the camshaft sprockets and one on the crankshaft pulley. Follow the manual instruction for this part. If the camshaft marks are not anywhere close, turn the engine another revolution clockwise and start the alignment process again. Don’t turn the engine counter clockwise.
12. Using a suitable tool (can be fabricated from angle iron or flat stock) to hold the crankshaft pulley and remove the 22mm retaining bolt. (See general comments above for more info)
13. Remove the crankshaft pulley - a pulley puller may be necessary to remove the pulley.
14. Mark the old belt and “sprockets/gears” at each cam belt pulley and at the crankshaft belt pulley (you need to follow the manual or know what you are doing here). I mark the old belt as if I am going to reuse it, then transfer the same marks to the new belt. This ensures you get it right – it’s fool proof.
15. Remove the tensioner tube by loosening each of the two bolts alternately, a few turns each, at a time.
16. Remove the timing belt guide ring (concave side goes out).
17. Check the tensioner tube, if you can depress the push rod into the housing by hand (by pushing it against a hard surface), replace the tensioner. Inspect the tensioner damper for oil leakage that would reduce the tension that it applies.
18. Check the tensioner pulley and replace if it has excessive play, makes any noise or does not feel right.
19. Reset the tensioner tube hydraulic damper. The standard procedure for hydraulic damper retraction is used to depress and pin the damper push rod in a vise or press. Make sure even and straight pressure are applied, and install a 1.5 mm hex wrench or pin to hold the pushrod in the retracted position. (You need to follow the manual or know what you are doing here)
20. Remove the old timing belt.
21. Transfer the same marks from the old timing belt to the new belt.
22. Install the new timing belt by aligning your transferred marks, while insuring the cam and crank alignment on the motor are also in agreement – it’s very important to get this perfect (you need to follow the manual or know what you are doing here).
23. Install the tensioner tube hydraulic damper by alternately tightening the bolts after making sure the dust boot is in position. 20ft/lbs
24. Remove the hex wrench or pin from the tensioner body and allow a few minutes for the tensioner to stabilize pressure on the belt.
25. Install the timing belt guide ring (concave side goes out),
26. Install lower timing belt cover.
27. Install the crankshaft pulley bolt hand-tight. After checking that all the proper timing marks are aligned, turn the engine over by hand, clockwise only, at least two full turns and recheck timing mark alignment. There should not be any restrictions, except the compression of the engine. If it wasn’t such a chore, having the spark plugs out makes this step easier and more conclusive that there is no valve-to-piston contact. If the timing marks are off, redo the procedure rather than take the chance that a mistake was made.
28. Install the crankshaft pulley bolt to the proper torque 239ft/lbs. Hold it with proper tool (see references above).
29. Install serpentine belt pulley bolts 15ft/lbs
30. Install two upper timing belt covers.
31. Reinstall removed shroud, fan, battery box and battery.
