ls400newbs

Hi,

Sorry for my ignorance, but I'm extremely new to all of this stuff. And I am struggling like hell to figure out what I NEED to get my maintenance done. I've done research online and I'm now trying to find what I need to order.

I need a lot of stuff (timing belt, seals, pump, power steering, etc), but I want to start with a couple of things. I also want to do a tune-up to the car, but I'm new to it all.

For example, I'm trying to buy plugs and coils on the o'reily website. (I tried the lexus website but I got lost with how they organize their inventory. I couldn't find the things I need.) Anyway, O'reily says that both wire coil-on-plug boots and coils fit the ls400. But I don't know what the difference is. Do I need both?

They also recommend the NGK Iridium sparkplugs.

I hope I'm not annoying you guys. I'm just really lost. I can do the work, I just don't know what parts I need. Thanks in advance!

RA40

iTrader: (6)

For your '99 changing the coil packs isn't necessary unless they are not functioning. Just change the plugs. Plugs can go beyond 100K miles on a well running LS.

Other considerations are the ECT sensor and O2 sensors. Fluid inspect-change for the transmission, brake, power steering and differential.

Is the power steering system leaking or exhibiting issues? The timing belt service will cover the water pump and cam seals if you option that service.

Einzelherz

The plugs are pretty easy. I just put the long life NGK iridiums in My 98. Make sure you've got some socket extensions and a swivel sparkplug socket (magnetic helps). You'll also need a 10mm socket to remove the engine cover, the air resonator/vacuum box (be very careful with this as the vacuum hose nipples are known to break), the intake assembly, and the coil packs. You can change your air filter while you're in there if you need it.

ls400newbs

I saw fluid dropping from the alternator, and around the power steering area. I'm assuming that's what leaking. The whole bay is dirty so I'm not sure what exactly is the problem but the fluid is mostly around the PS.

What's the reason why it's suggested to use ATF fluid instead of PS fluid?

And yeah, I'm planning on doing seals and wp as well. I want to bring as much as I can back to life, just without completely breaking the bank lol

RA40

iTrader: (6)

Toyota specs an ATF DEXRON II or III type for use in their PS systems. Other forums have posted about owners using PS fluids with varying results. I've not compared fluid specs between the recommended ATF and a PS fluid.

ls400newbs

Hope I'm not annoying you asking you so many questions lol. I'm going off a guide I found on Flickr for a 98 ls400.

The guy listed what he used and most of it is compatible. I want to double check if possible and see what else I can order to maintenance/upgrade.

This is what he bought himself for his timing belt service:

​​

I already added the ls430 alternator to the list btw 👍

You mention cam seals in your suggestions. I didn't see him mention it or do it in his guide. Do you know what the part number is? And how vital is it to the service, how do you tell if it should be done?

I plan on doing the O2 sensors afterwards. From what I've read, it's not too bad. Do I benefit from doing it now when the engine is all open? If so I'll do them along with the TB.

Same with the fluid change. Is it best to do the ps and transmission while it's all open? Or does not make a difference?

I​​​​​​​ haven't read on the etc sensor yet but it's on my mind now, how important is it to change it?

Thanks so much

RA40

iTrader: (6)

Happy to help.

Refreshing the cam seals is a bit different on the VVTi. I'd refer to some of the past threads on the importance and difficulty.
This is one thread:
https://www.clublexus.com/forums/ls-...l-refresh.html

O2 are far back from the TB service area that will be a separate maintenance task. Just make sure to spray in a penetrant to make removal easier if the exhaust system shows rust spots. Have a good O2 socket or flare wrench as they can be difficult parts to remove on some cars that see snow-salted roads.

The fluid changes are not that difficult with the front apart or together. Check the PS lines to the rack. With the PS area clear, those will be easier to work on like the P/S idle up valve that is a common leak issue, alternator killer.

The ECT sensor is easy so your discretion if you want to change it. At the higher miles they tend to come out in pieces due to the heat cycling resulting in brittle plastic. This sensor allows the ECU to adjust fuel trims based in part on engine temp. If the car is getting poor MPG and performance this is one of the sensors to check if it is the original part. Typically on the forum we see these being replaced in the 125-180K miles range. In an overall refresh and combined with O2 sensors I feel it is a good measure to replace.

All this adds up so do at your wallet comfort. The more critical maintenance given the priority over something that may not be showing any symptoms at this time.