My 99GS4 just passed the 120K miles marker last month. It still has the original timing belt and water pump.
I order the timing belt, water pump, #1 & #2 idler pulley from Carson Toyota.
I don't have a copy of the service manual. However, I have done lots of research in this forum regarding timing belt and water pump change procedure.
I have found some DIY guide with step by step instruction and photos for LS400. Nothing with similar details for the 2nd Gen GS400.

The following may contains lots of error but it is my vague understanding so far. (do not try to follow the steps in here for your install. The procedure is here to solicite input from club members)
1.remove trany and coolant line to radiator, take off all the bolts and electrical connectors and remove radiator.
2, lose tension by turning the drive belt tensioner pulley with a rachet and take off drive belt,
3, remove crank pulley bolt. There seems to be many different methods discussed in the forum. 3a)The most easy one being placing a breaker bar with 22mm socket on the CR bolt against the ground, crank the starter a few time without starting the car(remove all 8 electrical connectors to each indivual coilpack should do the trick). This should loosen the CR bolt. It sound easy. However, I have reseration regarding the possibility of damage done to the s tarter and the fly wheel.
3b) using old drive belt wrap around the CR pulley and tight the other end to the front stabilizer bar. This will lock the CR pulley in place while using rachet with long extension to take off the Cr pulley. Could this damage the CR pulley?
3c) I have heard many said that using air impact gun will not remove the CR pulley bolt. The success rate is not really high even combine with heating the bolt with a propane torch. I have a craftman compressor and an impact gun that is rated at 500 ft.lbf, I have used it in the past to done timimg belt change on my 95 Acura Integra(CR pulley bolt, 177N.m, 130ft.lbf) and 95 Toyota Camry V6 (CR pulley bolt, 215N.m, 159ft. lbf). I know the lexus CR pulley bolt is rated more than 200ft.lbf. I beleive using air impact gun is the safest route. I done research and found that 1/2" drive, Igersoll rand model 2135, maximum torque of 700ft.lbf and burst torque of 1000ft.lfb. If this tool can remove the CR pulley bolt, then this could be a long term investment for some of the tough bolt in the suspension. I want to change my strut this summer.

For people have done the timing belt change. Which method did you use and why?

4. remove both left and right camshaft pulley cover to expose the timing belt.

5. rotate the CR pulley to line up the timing mark at TDC on the harmonic balancer and the mark on both left and right cams pulley line up. Then rotate the CR pulley 30 Degree instead of 50 degree in the service manual (Thank to VVT-i and gserep1 for pointing it out).
Did anyone point it out to Toyota? Does the latest manual still contain the error?

6. remove CR pulley/Harmonic balancer with a Harmonicbalancer removal tool that may be obtained from Autozone.

7. alternately loosen the 2 bolts that hold the hydraulic tension and remove the tensioner.

8. remove timimg belt.

9. loosen #1 and #2 idler pulley bolts and remove both pulley.

10. installed new idler pulley.

11. remove waterpump and install new one.

12. route new timing belt and install hydraulic tensioner.

13. ensure all the timimg mark on the new belt line up with the mark on the CR pulley and the left and right cams pulley.

14. rotate CR pulley two revolutions and check the timing mark still line up perperly.

15. reinstall everythings.

15. top off coolant and transmission oil.

16. Keep finger cross and start enginer. check for abnormal sound and coolant leak. If none detect and you are done.

I would like to attempt this project as DIY. I am sure the above procedure has lots of steps missing or even some of the them are not in the correct order.
I would appreciate you guys comments to correct my mistake so I can get the job done right next weekend.
Better yet, can someone send me the section of the timimng belt and water pump procedure from the factory service manual.

Thanks in advance.
Ben



Update, I completed the install and car run great. couldn't be any happier.

 

Bro, from what I've heard - its a big job, it not a normal timing belt job, Ive found somone to do it locally for $400 + parts, to attempt to do DIY it, I give you

 

Ben I have no idea what level you are with mechanics, but with VVT-I I was a scared little woman and had a dealer do the timing belt. wrong move and pow 3K heads to buy. If you have done your homework maybe, even with that i didnt do it. for the extra 400-500 $ I would let someone else handle it.

Remember if you are asking, you are not sure.


D

PS ...happy fat tuesday...

 

I can't say that I am really good mechanics but I have done all the maintenance on my cars. Timing belt, water pump, suspension change and drive shaft change on both my Integra and Camry.
If I have the factory service manual, I would review all the step and things should be pretty clear.
I am only concern with how to properly take off the CR pulley bolts. Once that is done. I should be able to follow direction on how to properly set the timing belt.
Should be OK.
Thanks for the caution on how tough the job it.
I am willing to try it if I can get all my home work done.
Ben

 

I am only concern with how to properly take off the CR pulley bolts. Once that is done. I should be able to follow direction on how to properly set the timing belt.

Same area I was concerned about. I guess when you think about it the tundras and other toyotas are all the same set-up. So with a TSM you should be able to do it. forgot if you need a special tool for this or not.

D

 

The weather was really nice this weekend in Chicago ( in the upper 60) so I tackled my timing belt and water pump project.
Everything went pretty smooth except for the waterinlet housing assembly which is really stuck on the water pump housing. It took lots of tapping by a softhead hammer and WD40 to break loose the bond between the two. I did not want to break anything so I took my time to take it off.
The crankshaft pulley was no match for the Ingersoll rand 2135Ti impact gun. Just two seconds and it came right off.
I saw some oil at around the crankshaft. It could be the crank seal is leaking. Or it could be dust combined with WD40 that ran down the engine block that I used to remove the waterinlet housing assembly.
Have anyone replace the crank seal themselves. Is it hard?
Lexus serivice manual indicated that I need to remove the crankshaft timing pulley on the crankshaft which require a speical tool.
The harmony balancer puller I got from autozone does not have any screw that wil fit in the holes in the timing pulley.
For people who have done it, what tool did you use?

There is also confuing part on the service manual regarding rotating the engine another 50 degree after TDC which make the crank and cam pulley does not line up with anything.
I turned around 30 degree which the crankshaft pulley will line up with a white mark on the timing cover and both cam pulley lined up with the T mark.
I also spoke to JPI (thanks for clearing this up for me, the local Lexus dealer is no help) this morning and he confirmed that all you have to do it leave the mark on TDC. No need to rotate anything.
Why would Lexus service manual suggested me to rotate the engine to have the crankshaft pulley line up with an imagenary line to the center of the idle pulley #2 is beyond me?
I will try to finish my project next weekend.
Here is a photo during my install.
thanks,
Ben

 

Awesome bro

 

I finally have time to complete the timing belt and water pump installed.
Car run super smooth and no leak.
I want to give tremendous thanks to koolaidman who have guided me through some of the install on the phone.
I took lots of photos during the install.
If you guys need a DIY with lots of photo, I will try to do a write up and post it here.
Let me know.

 

ya i forgot to mention u dont need a puller. i just use my trusty screw drivers aka pry bars and a hammer