Hello, and thank you for choosing Just Answer to help you with your questions! How many miles are on your 4runner?

And is this something you've recently purchased, or owned for a while? If you've owned it for a while, did this noise suddenly appear, or has it sort of always seemed to be there?

how many miles are on it?

Ok, these engines are real prone to valve noise. Chances are, the valve lash has never been adjusted. This engine doesn't use hydraulic lifters, it uses shims on top of the valve buckets. Over time the valves tend to wear into the head a bit (this is normal) and the valve lash clearances tend to be a bit excessive, in essence "slamming" the valve shut when it closes. This makes a tapping noise

It isn't a huge deal to have them re-shimmed, your local dealer should have no issues with it

Like I said, it isn't uncommon at all on the vz series engines. Typically it isn't a big deal. However if left unattended (especially on the 3.0... the 3vz that was in the 4runners before the 3.4 that yours has) will beat the valve seats out of the head. This does take a while though

You'll slowly lose compression, and need a valve job.

Typically you won't see this happen in the 3.4 until well over 200,000 miles, closer to 250-300k range

but there are too many variables to tell for sure

Typically, about $500 or less. Most of this is labor, and it really depends on your local area, how much the labor rates are in that area, etc. They could be anywhere from $70/hr to $150/hr depending on where you live in the country

But I'll tell you the same thing I tell everyone that is looking at buying a used car. Before you buy it, take it to the dealership (not some local independant shop, the dealer knows exactly what the problem areas (if any) are on a vehicle, and exactly how things are supposed to look/sound/taste/feel like

They'll usually charge a half hour to hour labor for a 'pre purchase inspection' to look it over real good, and they can give you a list of anything that is good, stuff you'll likely need to look at in the future, and stuff that needs to be replaced soon

Make sure the timing belt has been replaced. It won't damage the engine if it breaks, but will just quit running wherever it happens to be which if it were one of my kids, I wouldn't want that to happen and have them stranded somewhere

Those water pumps have a tendancy to leak out through the weep hole. Doesn't mean it isn't working, just means it's aged and due to be replaced

If it is an auto, make sure the fluid is in good condition. This will be a good indicator of maintenance of the vehicle overall

it should be bright red when it is new

You can look at the back side (inside) of the rear brake drums, where the axle housing meets up with the backing plates. The axle seals have a tendancy to leak

You can tell the age of the spark plug wires by looking at them if they're still Toyota wires. Toyota prints the date year of the wires on the wires themselves. IF you look at them, you'll see a bunch of printed words. At the end, if they're original wires they'll say 1998

Axle seals won't show up as leaks on the ground unless they're REALLY leaking. You will be able to see what looks like a big wet spot on the back of the brakes. Usually it will leak inside the drum, get everything all wet and gooey and make a big mess

This depends on what kind of plugs were installed. platinum or iridium shouldn't

But really, this is little stuff. These engines, if maintained will easily last to 300k or more. It's a great engine and great trans

These are the toyotas that gave the reputation for lasting forever

I'm happy to help, if there is anything else I can help with, please let me know.

If you feel I have helped you, an accept would be greatly appreciated.

No problem. Good luck :)