Tight Exhaust Valve Clearances

While checking my valve clearances today on my 5S-FE (150k mi), I discovered that the clearances are too tight on all but one of my exhaust valves. The FSM lists a tolerance of 0.011" - 0.015" and I measured:

Cylinder 1 - 0.010" & 0.008"

2 - 0.008" & 0.008"

3 - 0.009" & 0.008"

4 - 0.010" & 0.012"



So my questions are:

-How imperative is it that I adjust them?

-What kind of wear does this indicate? I'm guessing valve stem wear . . . should I look into replacing them as well? (the seals that is)





Oh and I included a pic of beneath my valve cover:









Any comments/suggestions are appreciated.

Reply 1 : Tight Exhaust Valve Clearances

Ummmmm. The first three are way too tight on what I'm assuming is the exhaust side. I would definitely fix those, but the rest....I don't know...you would probably get away without fixing them.



but if you're doing one...might as well do them all!

Reply 2 : Tight Exhaust Valve Clearances

Tight clearances mean the valves don't contact the head long enough to dissipate heat. This can result in burned valves that are expensive to fix. I'd adjust them to mid range (13mils) as possible. You can swap shims to cut down on the number you need to buy. Consider doing the valve stem seals too.



I would say it's normal wear and tear. My guess is the steel valve seats get banged into the cylinder heads.



See also:

http://www.aa1car.com/library/ar1192.htm

Quote:

Originally Posted by agni While checking my valve clearances today on my 5S-FE (150k mi), I discovered that the clearances are too tight on all but one of my exhaust valves. The FSM lists a tolerance of 0.011" - 0.015" and I measured: Cylinder 1 - 0.010" & 0.008" 2 - 0.008" & 0.008" 3 - 0.009" & 0.008" 4 - 0.010" & 0.012" So my questions are: -How imperative is it that I adjust them? -What kind of wear does this indicate? I'm guessing valve stem wear . . . should I look into replacing them as well? (the seals that is)

Reply 3 : Tight Exhaust Valve Clearances

Picture of a burned valve:

Reply 4 : Tight Exhaust Valve Clearances

Thanks John. This is what I was afraid of. I'll try to adjust them as soon as I can, but I was just wondering if it is an immediate problem. Is it likely that I'll burn a valve if I don't correct these clearances very soon, or that one or more of the valves is already being damaged? The article that you linked to says that burned valves are common on older engines with soft valve seat material, but does anyone know if it commonly happens with this engine? EDIT: I just noticed that the picture you posted is from a 5SFE cylinder head? Do you by chance know how badly out of spec it was?



Chris: Yea the numbers I listed are for the exhaust valves only. All of the intake clearances were well within spec But yea, I agree that 0.008"/0.009" definitely call for adjustment - glad I checked them. Also explains the loud ticking coming from my valvetrain

Reply 5 : Tight Exhaust Valve Clearances

Looks like it's starting to sludge up too. I'd move to synthetic if you aren't already running it. Are you making short trips? If so, lengthen them to get the engine up to operating temperature for longer periods of time to burn off the moisture accumulation in the oil.



Next, you might need to accelerate oil change intervals, which may get expensive.



Check the PCV valve and breather line to ensure there isn't any obstruction in either.

Reply 6 : Tight Exhaust Valve Clearances

Quote:

Originally Posted by Jason.MZW20 Looks like it's starting to sludge up too. I'd move to synthetic if you aren't already running it. Are you making short trips? If so, lengthen them to get the engine up to operating temperature for longer periods of time to burn off the moisture accumulation in the oil. Next, you might need to accelerate oil change intervals, which may get expensive. Check the PCV valve and breather line to ensure there isn't any obstruction in either.

Yea it was pretty sludgy when I bought the car about 9000 miles ago. I've been doing regular oil changes with Castrol GTX and good filters - every 2000 miles or less. I've also run seafoam through the crankcase a few times. I was reluctant to use synthetic because I had a pretty bad oil leak, but I just did a full timing belt job including all of the seals so I'll probably make the switch after my next oil change. I've also heard of people running ATF through an engine for a few minutes to clean out all of the sludge. I'm guessing this isn't a recommended method though...

Reply 7 : Tight Exhaust Valve Clearances

ATF can be used at your own risk, and only at idle. Drain when hot after idling for about 15-20 minutes. It's an old trick to clean out an engine. I wouldn't recommend it, but it works.



1/4-1/2 quart for every 4 quarts is a conservative amount.



1-1 1/2 quart(s) for every 4 quarts is aggressive.



Full ATF is considered a last resort, though a full rebuild would be a more prudent measure for engines in bad shape.



ATF is a high detergent oil, so it will clean up the engine a bit better. Just remember to flush the ATF completely out by doing a full oil change, idle for 2 minutes, and drain/refill.

Reply 8 : Tight Exhaust Valve Clearances

Well I tried to pull out the shims today without success. No matter how hard I pushed/pried with a screwdriver, I could not depress the lifters far enough to pop out the shims so I gave up for fear of slipping and damaging something. I'm thinking about buying an aftermarket shim removal tool from Ebay. The description says that it will work for "most Toyota overhead cam engines using spacer shims" but doesn't list specific engines or a SST#. Has anyone used one of these with success?