The valve clearance CHECK is ~30 minutes on top of a valve cover gasket replacement job. Might get 'er done in a day if you're quick with the wrench, otherwise plan for an easy weekend. At 190k, all of mine were in spec with only 1 even close to a limit.

I forget if the cams have to come out for the replacement, but I'd add another few hours if so. If it can be done with the cams in place, then an hour tops (assuming you have a good selection of shims on hand, else you'll be having to custom order once you get the old ones out and measured). The most complicated part is the math, taking your measurement, the difference to your desired measurement with the current shim (measured, some are marked but you always want to measure) and the difference needed (new shim size).


As for what it does: Too tight of a valve clearance means the engine can't breathe as well as possible (think asthma). Too loose of a clearance and you're going to be losing compression (ballon with a hole). Either of those get too far out and you're going to run into hard-start situations (usually hard to start when hot but starts easily when cold ~ can be the inverse though). You also run a risk of burning valves when too loose. I can tell an operation difference in my '66 Beetle engine as I get over 2k miles... has a 3k inspection/adjustment interval.

I have two 3rd gens - an '01 that I purchased new, and an '02 that I purchased two years ago as my daughter's first car. Both are non-sunroof Dorado Gold/Oak SR5 4WD autos.

The '01 has 516,700 miles and the '02 has 208,000 miles. Both on original engines & transmissions (I purchased the '02 from the original owner who I've known for years).

I do absolutely all of my own maintenance/repairs/upgrades. On the '01, I've done two timing belt jobs - one at 171,000 miles and the second at 350,000 miles. The third one is coming up soon. I am religious with 3,000-mile oil changes using Castrol GTX 5w/30 and a Toyota filter. Air filter and plugs replaced every 25,000 miles, and a full transmission flush every 100,000 miles.

I have a ridiculous amount of parts receipts since 2001 and refuse to add up what I've spent.


Andreas

I figured the exchange of transmission fluid every 100K would extend the transmissions life. :-)

Did you change the radiators on occasion? I change mine every 10 years on my autos just to make sure I keep the pink milkshake away. :-)

516K is doing well.. Congrats.

^ Yes, I've replaced the radiator a few times in the '01 (not just during the timing belt jobs). I installed a new Toyota unit in the '02 a few weeks ago - it was original and gave me nightmares.



Andreas

Yeah I really need to get around to doing that.. Don't remind me! Haha. She still has good power all throughout the power-band and drives & starts fine. Probably will tackle it once I'm not super tight on money since I need to my my valve covers at the same time.

Dude! This gives me major inspiration for my Dorado gold 01, lol. 500K miles is a lot and I definitely am going to make every attempt at getting my truck there. I think it's possible. But it's gonna be a while before I get there.

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I have 3999893 miles on 99 4 runner

Nearly 4 million miles is incredible! Are you driving as you read this?

You can buy a valve spring compression tool to do the valve shims.

Last one I did I used the tool for the intake cam and pulled the exhaust cam.


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