2.4 Valve Clearance Measurement Question

I measured my 1996 Tacoma's valve clearances last weekend at 201,000 miles. They haven't been checked before. Here's what I found:

Millimeters - It's a Japanese truck right, no inches...

EX IN
.35 .20
.35 .20
.36 .19
.31 .20
.35 .21
.35 .21
.36 .21
.36 .21
Front of Engine

Factory specs are .25-.35 on the exhaust and ,15 to .25 on the intake.
It would seem to me that the Exhaust is ever so slightly on the high side and the intake is right in the middle. After that many miles, I would have expected it to be tighter. My question: should I mess with it? It doesn't seem worth getting shims and replacing the exhaust at this point. I've read that tight is bad loose is better. Is there any harm in letting it go for awhile longer? THANKS!

 

They look OK to me. Loose is better than too tight because tight won't allow the valve to close completely and it will burn.

 

That's plenty good, hard to believe at that milage. Usually in time the valves will "pocket" in a little closing up the clearance. I would not change anything with those readings.

 

Thanks for the input. I was really surprised when I measured it. I checked it 3 times just to confirm. I was a bit worried since it had never been checked but now relieved. I'll keep trucking for now.

 

200k and the exhaust have only changed maybe 0.05mm, so another 100k I wouldn't expect much more change. This design stays within specs for a long time. Give credit to Toyota.

 

do you have to do anything, no,

but for the sake of a smoother better running engine,

I would replace all the exhaust shims except for the one exhaust shim for the .31 .20 cylinder to change them all to .30 or .31 so things are in the very middle of the range. having all your exhaust valves set with the widest range gap will mean they don't stay open as long as they should so your not getting all the exhaust gas out efficiently as it could.

I don't like to see them more then 2 numbers off from each other as a group so the .19-.21 all look good but the .35-.36 all are on the very outside of the listed range and should be fixed to get back to the middle of the setting range with the one exception of that reading of .31 so that cylinder will not be needing the exhaust shim replaced as the others do. these engine idle rough enough if everything is set good so anything you can do to keep everything evenly balanced and in the correct ranges listed is the way to go.

whenever you have a range for something to be set at, you never want it to be on either end of that range, you want it to be dead center as best as it can be

 

There's no guarantee they can be adjusted to .30-.31mm or all within .01mm of each other. New shim sizes are multiples of .05mm, so the only guarantee is you can get them all in the range .275-.325mm with new shims.

For example, current clearances of .36 and .36 might have current shims measured at 2.52 and 2.50. Ideally, you'd replace with 2.58 and 2.56 to bring the new clearances to .30, but the closest you can get with new shims is 2.60 or 2.55. So the first clearance would be .28 (with 2.60 shim) or .33 (with 2.55 shim) and the second .31 (with 2.55 shim).

You can shuffle some of the old shims around to try to get all clearances a little closer to each other. Unless you have a whole buch of spare old shims in odd sizes, you will still have variances of .02-.04 between valves. I think the Toyota engineers knew this and decided it didn't matter.

Perhaps you could adjust the average of both valves in each cylinder to try to make all cylinders as even as possible.

 

ok, I thought they came in multiples of .005

 

Thanks for the additional comments. Memory fades, but it doesn't seem like it idles any rougher than it ever has. I think I'll recheck the tolerances in another 30,000 or so and then see where it's at.