Tight Exhaust Valve Clearances - Toyota Nation Forum : Toyota Car and Truck Forums

agni · 03-13-2011, 10:30 AM

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.

Chris Crash · 03-13-2011, 12:01 PM

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!

***JohnGD*** · 03-13-2011, 02:11 PM

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)

***JohnGD*** · 03-13-2011, 02:13 PM

Picture of a burned valve:

agni · 03-13-2011, 07:52 PM

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

Jason.MZW20 · 03-13-2011, 08:37 PM

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.

agni · 03-13-2011, 09:28 PM

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...

Jason.MZW20 · 03-13-2011, 10:14 PM

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.

agni · 03-18-2011, 12:28 AM

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?

***zythr*** · 03-18-2011, 09:01 AM

Quote:

Originally Posted by agni

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?

I thought the shims were removed using a magnet?

agni · 03-18-2011, 02:29 PM

Yes a magnet is used to lift the shim out from the lifter bucket. But the lifter must first be depressed, because the small clearance between the shim and the cam lobe makes it impossible to remove the shim otherwise. I read somewhere that each valve spring provides ~150lbs of force - so it's not as simple as just pushing the lifter down with a screwdriver. The easiest way is to remove the camshaft, but I don't have the proper torque wrench to re-tighten the bearing caps. Also, I'm not exactly sure how get it realigned.

73sport · 03-21-2011, 11:46 AM

agni,
You'll end up pushing right on the edge of the lifter bucket with a HUGE screwdriver using most of your body weight. It is not EASY! You're intent is to open the valve which is fighting back with 90+lbs of force to force the valve from its seat. The cam lobe should be up and then use tiny pick and magnet to pull the shim. Two people is a benefit here, but one can do it if your upper body is up to the task.

The shims will be hydro locked into place by the oil trapped under them. They can be tough to get out so rotate the bucket so a pick can get into the open slot. Once a corner is up, now use a magnet.

If I can do this on the back bank of V6, you can do the I4.

FWIW: valve tip wear could increase your clearances but this is a very low were spot on this engine design. If the end of the valve, the contact point inside the bucket or the base circle of the cam wear, all these things will increase the clearances not decrease them.

Bad gas for a long time will increase wear to the valve seats and valve face. As the valve seats deeper into the head, you loose valve clearance as the valve tip is now closer to the camshaft. As stated above, holding the valve off the seat can lead to burned valve(s) as they do not get cooled if held open. Also Like Chris said, the varnish on the cam could account for the measurement you have.

Use some lacquer thinner and clean the base circle of the cam and make sure the lobe is at the proper position (via crank shaft rotations for making the measurement) and take some new measurement after its cleaned. If they still show being tight, take action.

Also while tampering and cleaning stirring up sludge, Id use the WIX 51515 1 qt filter unless you plan to do 1000 mile oil change intervals.

EDIT::::::::: After cleaning the varnish off the cam, poor some oil on it BEFORE you start IT or crank it repeatedly. How is the compression anyways? Have you checked it?

Here is the lifter bucket you are trying to depress. Push on the edge. . . .

agni · 03-26-2011, 07:46 PM

Thanks to all for your replies.

I ended up just removing the camshaft to access the lifters, since I needed to replace essentially all of them. Luckily, I was able to find the needed shims at the salvage yard, which saved me from being robbed by the dealership in exchange for little metal discs. Additional thanks to 73sport for the suggestion about the varnish on the cam lobes - I can't believe I didn't think of that, especially as the only ones without varnish (#4) had the largest clearances . . . . But I adjusted them all to .012/.013, so even if some varnish wears off I should be within tolerance. I just switched to synthetic oil, so I'll recheck them after 10k or so just to be sure.

I noticed another interesting problem while removing the camshaft: the holes for the "service bolt" were not aligned, meaning that whoever removed it previously was oblivious to the existence of the spring loaded scissor gear. Indeed, the spring had been unloaded and didn't rotate at all during removal. With a little brute force and prying with a screwdriver, I was able to reload the gear and get it aligned properly before reinstalling it.

My engine is now MUCH quieter. Listen for yourself: BEFORE & AFTER. I now believe that the major source of the noise was the scissor gear, though the tight valve clearances may have contributed. What do you guys think?

***fenixus*** · 03-26-2011, 08:44 PM

nice difference

good job with spotting service bolt holes not lining up too

so what are your valve clearances at now? did you measure all of them or just the exhaust ones?

***Silent Runner*** · 03-26-2011, 11:30 PM

This is a good thread, along with the responses, I've finally figured out how valve clearances are set on this engine, and i'd assume its the same on the V-6's only its 24x. On my valve cover job, I looked and couldn't even guess how they were set. Fortunately, I noted that a dealer had set them on my car only 30K miles or so ago. Good job on figuring out all the problems with and associated around your clearance and noise issue. Some pretty smart folks out here!