To start off Hello, my name is Colsen and I have recently (5 months ago) bought a 1996 LS400 for $1500 and currently at 212,000 miles and is in pretty fair condition I'd say.
It has its problems for being a cheap car that I bought to learn how to work on (not my smartest move) but there are really only about 3 main problems with it at the moment.

First off being a oil leak. I have already taken it to a shop and had the valve cover gaskets replaced and bolts tightened but still leaks slowly. I have had some people tall me that it is the cam valve seals on the left side of the motor if you are looking at the front of the car. I was hoping to see if any one has gone about fixing that themselves and how hard/ annoying it was, or what other things it could be that are leaking from that area.

Second is my starting issue. If the car sits for a day or two sometimes it takes a bit for it to start and sometimes while driving to go run errands it might take a second to start up. I've checked the battery, starter, and alternator and all read back good. What would be the chances of the spark plugs going bad or would anyone have an idea to what might be causing this?

Third is I'm assuming my PS pump might have a leak or maybe some of the lines. I don't have a good way to get under the car and look at everything besides jack stands.

My CEL is also on for catalytic inefficiency below threshold 2. I did have a good and reputable shop do a custom 3" exhaust from the middle cat/resonator thing back. My CEL is on every now and then because of that and I was wondering if it would be worth it to replace the cats with test pipes and add some mufflers to the rear or what would be the best way to go about that being that next year the car will be 25 years old and emissions testing won't apply to it anymore.

Sorry for the big post, First time here and just wanted to lay it all out

 

I’ve done the cam seals on a 95 and a 96 LS before and it was easy for me to do with basic hand tools. Just the same as a timing belt change with a couple of trivial added steps.
But I did have a little bit of casual wrenching experience at that point.
If your LS was bought to learn wrenching on, then it shouldn’t be your only means of transport.
If you weren’t comfortable replacing the valve cover seals yourself (extremely easy on the LS400) then the camshaft seals are an order of magnitude more difficult and risky to accomplish as a total novice.

 

1) Can you get under the motor and see where the leak is coming from? What part of the engine? Would help narrow it down. Leaky cam and crankshaft seals are a common problem for the car. Also possible it's the rear main seal, though much less likely.

2) Starter motors are a weak point of the car, mine has had it's starter replaced twice in it's lifetime according to records I got with the car. Does it ever fail to start? Or does it sometimes just feel like it takes a second or two longer to start than it should?

3) The power steering pump will leak on almost all cars, and conveniently leak onto the alternator, frying it and leaving you without power. First generation cars can also leak from the power steering reservoirs onto the alternator, but the reservoir location was moved I believe in 98. Also, if power steering fluid level drops but you don't see a leak, or if there's a puff of white smoke on startup, then you have a leak from the idle up valve that uses vacuum to raise the idle when the power steering pump is operated. It's screwed in to the pump and has two vacuum lines coming from it.

 

It's mainly my project car, my daily is a 2019 Subaru Impreza. I've started working on cars recently but I have a few people that said they would gladly help and they are all pretty experienced with American V8's. At the time i didn't have many hand tools so i sent it to a shop but i have gathered up a good few now

 

Welcome! The LS is a reasonably easy car to work on and learn some things on. You should definitely hop on drivers.lexus.com and make a free account and add your VIN to your account. You will have access to all Lexus/Toyota service records for the vehicle.
The power steering leak definitely needs to be taken care of quick. If its the pump leaking, and it probably is, it will leak onto the alternator below it and possibly leave you unexpectedly stranded. As others mentioned, there is also an Idle Up valve attached to the power steering pump, with 2 vacuum lines that run into the plastic intake. These valves ALWAYS leak, I have deleted them and plugged all the holes on both of my LS400's.
If your car still has the plastic under trays, grab a good ol' 10MM and remove them to get a good look underneath. If everything is just a grimy mess, get some engine degreaser and hit the local spray wash. Do NOT power wash the engine, but the undercarriage and front of the motor can handle some water. Common oil leaks are the valve covers and spark plug tubes, rear main crank seal, front crank seal, and 2 camshaft seals. With everything relatively clean and plastic covers out of the way, it should be easy to find the oil leak.
As for the cats, yeah either replace them or just remove them since emissions wont be a problem soon. The same code is also common for exhaust leaks at the front exhaust flanges. New primary O2 sensors would probably be good too.
Check out the service records and see what has already been done!

If you have a harbor freight in your part of the world, they have all the tools you need.

 

At 20+ years old, all of the rubber seals in these cars have shrunk & become harden that's why they're prone to leak. The proper way of fixing is to remove & replace them with new seals, however it's very time consuming & can be quite expensive if you're not a DIY'er so here's a quick & easy solution & most likely it'll fix your engine oil & ps fluid leaks: Get a bottle of ATP AT-205 Re-Seal Stop Leaks for about $12, pour about 1/5 of it into the ps reservoir & the rest into your engine then drive as usual. The AT-205 is a plasticizer, a type of chemical used to rejuvenate & restoring the flexibility of the rubber seals. Good luck.

 

1. I know the general area of where its leaking from. I know its not the rear main seal. I'm going to assume its the passenger side of the motor and the driver side is leak free as of now.
2. never has failed to start, just sometimes takes longer than it should. or when it starts its kinda like its chugging to start
3. I'll have to check on that in the morning and see if there is any smoke on start up

 

I have no experience using products like that for sealant so I'd love to know more. Are they stable over the long term? Or is it just a temporary stop-gap? I would guess things like that were just a band-aid until you could properly address the problem.

 

The smoke, hard starting and PS leak are likely related to each other. When the idle up valve on the pump fails, it can dump PS fluid into the intake of the motor.

 

I wouldn't bet on the stop leak product. Just replace the cam seals. If you want to learn it as the project car, use this time to replace timing belt and water pump too. It takes time because the design requires several hours removing stuffs before actual doing real timing belt work so it easily takes 2 days. But the instruction is straight forward, if you can read the manual, you can do it.