Hello all, new owner of 3rd gen 4Runner here. (1 Viewer)

[Didymus]

I just got myself a 325,000 mile original engine (running) 1999 3.4L 4x4 4Runner. In the past I've been a snob about how I only love the 1st - 3rd gen pickups and 1st - 2nd gen runners, I have now seen the light.
I've been lurking here doing some research into what I need to take care of first. I'm definitely going to do the Taco brake swap and check out my ball joints, after that I'll have to look into why it had a P0171 that hasn't come back since I reset it.
I'm mostly here for a bit o' friendly advice on things I may have overlooked while reading the FAQs here. Honestly the engine is running great right now even though it was running on 2 quarts of sludge when I got it, good gas mileage and all.

I still haven't had time to get it on a lift but I'm going to make a boring list of things I plan on doing because I feel like typing tonight! If ya'll have the time to read it please let me know what I'm leaving out.

Brakes & brake fluid + clutch fluid flush
Rear springs
Suspension inspection & alignment if all is well
Tires after alignment
Air filter
Compression test
Plugs and wires
Throttle body & injector cleaning
Coolant flush
Fluid drain & fill in all gearboxes
Frequent oil changes until the sludge is taken care of (10w-30 once the weather warms up?)
P-brake dash light intermittent short fix (Only elecrical issue so far!)
A/C diagnosis & fix

I'm wondering if anyone has any guesses on how long this engine might last before it takes a dump on me? I'm really hoping (praying) to get some good miles in before I need a rebuild or replacement.

Pics coming soon because I'm proud of the moss growing on the roof.

 

[White Stripe]

Nice. If the motor has sludge it could be a ticking time bomb. Could last another 200k or 5k depending if a chunk breaks off and clogs a oil passage. But used 3.4 motors are cheap and plentiful. Rear axle seals often leak at high mileage, and rear wheel bearings start to go around 300k. If the radiator looks old I would replace it to avoid tranny strawberry milkshake-that happened to me. P0171 may just be a dirty maf sensor. As far as front brakes-its the tundra brake swap, not taco. Front ball joints are also a good idea to replace. 3.4 motors can run a long time. I talked to one guy who has 400k on it, all of those miles with the supercharger on it. Here is mine with 225k...

 

[Didymus]

Derp, I meant Tundra, Taco is just more fun to type. Thanks for the advice! I'll be checking the hubs, ball joints, tie rods ect before I do the alignment and I'll definately clean the MAF. Hopefully the milkshake will be a non-issue with the manual transmission.
That's a good looking engine bay (supercharger envy), recent pic or is it put back together now?

 

[White Stripe]

Derp, I meant Tundra, Taco is just more fun to type. Thanks for the advice! I'll be checking the hubs, ball joints, tie rods ect before I do the alignment and I'll definately clean the MAF. Hopefully the milkshake will be a non-issue with the manual transmission.
That's a good looking engine bay (supercharger envy), recent pic or is it put back together now?

Oh OK if you have manual transmission then your fine. Another item that's often neglected is spark plugs. Not sure why being they are so easy to get too on the 3.4. Thank you, it's back together now. Was just doing valve cove gaskets.

 

[Didymus]

Welp, the MAF was definitely dirty. It's clean now but before I got around to cleaning it the puter threw a P0420. Codes aren't coming back but I can't get the dang catalyst monitor to ready.. I've tried the driving cycles defined in the TSB in the FAQ and also the one shown when you google search for how to clear it. This is becoming fairly annoying because I need to pass smog and though I love driving, driving at 55 on the freeway gets old. Plugs and wires will be replaced at the same time I do the fuel system cleaning.

 

[Didymus]

WELP, the P0420 came back. I had the monitors ready, just the catalyst wasn't ready but I'm allowed one monitor to be incomplete as far as I understand. I was on my way back to the smog shop (about 20 minutes away from where I had checked the monitors on my test drive) and just 3 minutes out the CEL came back on. :'( I'll just have to non-op the truck for now I guess until I can figure this out.

Edit:
I'm assuming buying a new downstream sensor would be my best bet. Should I just bite the bullet and buy a new upstream one as well? I just know buying the two would be cheaper than a new cat but I'm trying to keep costs as low as I can seeing as how I already have two street legal vehicles not including my wife's car.

 

[White Stripe]

WELP, the P0420 came back. I had the monitors ready, just the catalyst wasn't ready but I'm allowed one monitor to be incomplete as far as I understand. I was on my way back to the smog shop (about 20 minutes away from where I had checked the monitors on my test drive) and just 3 minutes out the CEL came back on. :'( I'll just have to non-op the truck for now I guess until I can figure this out.

Edit:
I'm assuming buying a new downstream sensor would be my best bet. Should I just bite the bullet and buy a new upstream one as well? I just know buying the two would be cheaper than a new cat but I'm trying to keep costs as low as I can seeing as how I already have two street legal vehicles not including my wife's car.

90% of the time you get a p0420 it's a bad cat. With over 300k on the clock I'm not surprised. Check your local Craigslist to see if anyone is parting out a 3Rd Gen and try and buy the down pipe with cat off of them. Or buy a new cat. If u have a obd2 scanner capable of reading live Data watch the secondary o2 sensor graph. It should be almost flat when warmed up. If it's up n down the cat is bad. I'm sure their are youtube videos on this as well.

 

[galandcruiser97]

Bite the bullet and buy the air to fuel sensor and the O2 sensor so you will knock the problem out.