OldLs400

These are the things I've fixed or done on my daily driver '98 ls400 so far:

• vvti/oil control valves
• hood strut/prop rods
• brake pads
• valve cover gaskets and pcv valve
• coolant flush and drain
• transmission drain and refill (5 times)
• power steering drain and refill
• starter replaced with junkyard salvage
• alternator replaced with reman
• oil change and new filters
• spark plugs
• ac recharge
• new battery
• differential drain and refill
• new serpentine belt

What are some recommended maintenance things that I should do?

I also read that some sensors commonly go bad. The crankshaft position sensor comes to mind. Should I just go ahead and replace these with original Denso sensors, or should I wait for them to actually go bad? Are there other things that commonly go bad that I should just do now rather than do it 6 months later? I just don't want to be stuck somewhere and be stranded. Are sensors like these worth preemptively replacing on a '98? Are there any more "must-do" maintenance items?

AlaskanLS

Save your money and don't spend a dime on it until you see the check engine light. I would recommend cleaning the EGR valves and replacing the 4 O2 sensors. New O2 sensors will save you a ton of fuel. Also replace the coolant sensors.

AlaskanLS

Check the timing belt also, if you see any cracks, replace it right away.

Yamae

A 98 doesn't have EGR valves.

Legender

I think I'm slated to do the O2 sensors as I keep getting the P0420 on bank one even after I either clean the MAF or swap in a new one. Going to try and read the values on my Torque app and see if I'm getting some bad readings somewhere to pinpoint, but after 230k miles, might be due for a replacement.
I've done most of yours above except for the starter. Haven't been there yet.
I have done the rear differential drain and fill though. Pretty easy with ramps. I'd recommend it if you've not done it already.
Also think I need to do the tranny pan removal, filter change and reinstall as I seem to have a bit of a tranny leak around the pan.
Want to wait till it cools off a bit though.
I just love the ride/feel of this car.

Michael88

Timing belt and water pump at 120k miles, if it breaks when driving this interference engine will be shot and require a new engine. Also, be sure the vacuum lines are dark black, soft, and subtle. Armor them. Make sure the power steering pump isn't leaking on the alternator. Watch the fan clutch, mine held up forever, but that made it hard to diagnose, if it doesn't roar at a cold start up replace it. Leather condition the seats and armor-all all the rubber seals around the moonroof, doors, windows, trunk, and hood once a year. Never run regular unleaded in it, only premium. Make sure the four drain holes around the moonroof are clear of debris. Replace shot hood pistons asap or run a chance of a misaligned hood from propping it up.

Fit1too

Learned something good today. I wondered why the fan roars when I first start the vehicle.
I wouldn't throw parts at the car. I have spent a small fortune doing that in the past, and have quit doing it. I also try not to obsess over the little things. The black 'A' pillar trim piece that touches the windshield on the outside is flaking and someone has touched it up rather poorly. That would have bugged me to no end the past and I would have probably broken something trying to get it off.
Anyway, use quality fuel, don't run it low, and eyeball the vacuum lines. Get a good motor club, we travel a lot and ours pays for itself within a matter of months with discounts on hotel rooms. There is no better piece of mind than being able to call someone to come and get you when something happens. Kinda like a bail bondsman for cars that go bad!

timmy0tool

iTrader: (7)

I would replace the transmission mount to return the drivetrain smoothness.
you might notice some vibrations at speed as a result of a bad mount (usually goes bad around after 100k miles).
very easily replaced and the benefit is night and day!

jaaa

Have you put the car up on jackstands/ramps to check for leaks on the cat/y-pipe flange connection? I know on my car the p0420 comes from a leak just past the cat at the flange.

Legender

Nope... good suggestion Jaaa, I'll try that first as I'll have to get it up anyways to do the sensors. Thanks.

Michael88

I have good luck with name brand black model paint from a hobby store for the window trim. Dab it on rather than brushing it on , if that makes sense. Other auto touch ups tend to just come off again.

OldLs400

I'm getting a Milwaukee mid-torque impact tomorrow. I'm also going to be getting the strut bar/rod tomorrow and I''ll be under the front suspension soon replacing the strut bar/rod. Are there any dead-simple things that I can refresh on the front suspension? Dead-simple as in a monkey with an impact wrench could do it? I have sway bar bushings in mind. Anything else?

bradland

Michael88

Sway bar bushings but you will need to know what size the sway bar is. Does anyone know? Or you could measure it by wrapping a strin around it nect to the bushing then use a ruller.

WaveRunner

I too have a 1998 now with 142k miles and I find the biggest expense and effort being the suspension wearing out. I suspect my wheels are cupping at the edge and there's an annoying knocking sound when steering that I can't pin point. I will find it and deal with it time permitting. The engine is flawless. I use Mobil 1 full synthetic and Toyota filter. I replaced the starter and a leaking steering rack within the last year and strut rods (the bushings were worn and caused a loud knock when hitting a bump or incline). Those were the only major issues I had since I've owned the car from Spring 2017. The ride is cushy but I suspect handling is being hindered by worn shocks. Replacing the shocks requires some effort especially the back as you have to remove the back seat to access the bolts for the strut mounts. By the way go only with OEM suspension components when economically possible. Consider KYB struts which are a fraction of KYB OEM struts.