Valve Shim clearance question (highly under covered topic)

[ajonesnv]

OK, so let me start off by saying that the truck has 207,xxx miles on her and I bought her with 112,xxx and has always had quite loud valve noise...kinda sounds like a diesel engine It is also fair to state that other than the noise she runs great...good mileage, no CEL, doesn't burn more than expected oil, or any other problems.

So here I am doing my valve cover gasket and thought I should check the clearances while I was in there. I found that two of the exhaust valves were waaaaay out of spec. the clearances on these were 0.064" and 0.051" (spec is 0.011" - 0.014" if I remember correctly). They are so far out of spec that Toyota does not make any shims that make-up the difference, which brings me to my question...

If they are that far out of spec what should I be looking for, problem with the valve seat, valve spring, or maybe something else??? My plan as of now is to fill the gap as much as possible and hope that she quiets down, but I guess Im just wondering if Im peeling back a potential problem that will cause my OCD go nuts.

For those tldr folks:
Exhaust valves out of spec. the clearances on these were 0.064" and 0.051" (spec is 0.011" - 0.014"). Toyota does not make any shims that make-up the difference...

If they are that far out of spec what should I be looking for, problem with the valve seat, valve spring, or maybe something else???

 

[Kryptoroxx]

Hmmm ok you can try lcengineering.com for the shims. I recently did my valves and I was close on a couple of exhaust shims but I'm not there yet.

I believe need to do your valve seats which will take pulling the heads sadly. I am fairly certain you cannot redo the valve seats with the head on the engine. If you do need to pull them better to do all of the seats at one time.

 

[ajonesnv]

Ill look into the shims, but like I said she runs great, so Ill leave the seats as is until something goes array.

 

[19963.4lsr5]

You really need to pull the shims in those two valves. And measure how thick they are.

And based on the out of spec difference plus the thickness of the existing shim you will know what thickness shim you need to find.

 

[KidVermicious]

You really need to pull the shims in those two valves. And measure how thick they are.

And based on the out of spec difference plus the thickness of the existing shim you will know what thickness shim you need to find.

This. You don't know if Toyota makes a shim the size you need until you know what size you need, and you don't know that until you know the current clearance AND the current shim thickness.

If they do turn out to be so far out of spec that you can't get a shim the right size, it could be valves themselves or it could be the lobes on the cam.

 

[ajonesnv]

You really need to pull the shims in those two valves. And measure how thick they are.

And based on the out of spec difference plus the thickness of the existing shim you will know what thickness shim you need to find.

This. You don't know if Toyota makes a shim the size you need until you know what size you need, and you don't know that until you know the current clearance AND the current shim thickness.

If they do turn out to be so far out of spec that you can't get a shim the right size, it could be valves themselves or it could be the lobes on the cam.

I did this, I realize this wasn't stated but figured it was implied based on how I was able to know that there isn't a shim (made by Toyota) to make up the difference.

 

[19963.4lsr5]

So what thickness did you pull out and what thickness does your math say you need?

 

[19963.4lsr5]

do the valve components on those two cylinders look normal?

How does the cam lobe look on them? Do you have a good caliper or a micrometer to measure the lobe diameter on them to see if it's worn?

A lot of things to look at.

 

[ajonesnv]

So what thickness did you pull out and what thickness does your math say you need?

I used the FSM chart to figure what I needed, this FSM also shows what shims Toyota makes and they make shims from #1-17. 1 being 0.0984" and 17 being 0.1299".

The largest gap I have is 0.064" the shim measurement for this valve is 0.1133". According to my math (0.064-0.014=0.05 0.113+0.05=0.163) I need a 0.163' shim to meet the spec, however Toyota only makes a shim up to 0.1299", which is #17.

The same math was applies to the valve that measured with 0.051" with a shim that measures 0.1122".

This may be unheard of, but the website referenced above makes buckets that insert shims into the bottom rather than sitting on the top. I wonder if I were to add a shim into the buck in conjunction with the shim on the top to meet the spec would cause any issues. Im doubtfully going to consider this, but it was a thought that crossed my mind.

 

[19963.4lsr5]

As long as your not getting the metric and conversion screwed up your correct.

Usually jap heads get tighter valves from the valve seat ware and the calves sink into the head. Yours is a odd ball. Is the valve fully closed?

Can you measure the spring and bucket height and compare it to another valve?

 

[davidch]

I think you'll find that shim-under-bucket engines have buckets intended for that purpose. The shims in these engines are much smaller, usually about 10mm in diameter, not ~quarter-sized as in shim-over-bucket engines. Can anyone provide a reference to a shim-on-both-sides-of-the-bucket cam train?

As someone else noted, one usually finds valve clearances shrinking, thus necessitating thinner shims.

This leaves the mystery: if your engine hasn't suffered lubrication failure (extreme and visible wear on the cam and follower) and if it's running well, just noisy (meaning you have compression, meaning there's not some bit of crud holding those 2 valves open) then why the big clearance?

(Such lubrication failure would likely not just affect 2 valves.)

A possibility: you're not the original owner. Do you have the service records? Was the head removed and the valves worked on before? What a machinist might have done, after re-cutting a badly burned valve seat, is find that now the replacment valve is too high or far into the head so that no shim is thin enough. The machinist then shortens the valve stem. Presumably a skilled machinist adjusts the stem's length so that a shim somewhere in the middle of Toyota's range of shims is correct.

And now the reveal: what if the machinist took off too much?

 

[19963.4lsr5]

The shims on the 3.4l are big Dia. It's 28mm

As for needing the thicker shim I think Honda and Yamaha motorcycles use that size too. But not sure on their thickness ranges.

But I think it's aby-normal for that much clearance. Stuff needs looked at before another shim gets slapped in. If one exists.

 

[02SE]

I think you'll find that shim-under-bucket engines have buckets intended for that purpose. The shims in these engines are much smaller, usually about 10mm in diameter, not ~quarter-sized as in shim-over-bucket engines. Can anyone provide a reference to a shim-on-both-sides-of-the-bucket cam train?

As someone else noted, one usually finds valve clearances shrinking, thus necessitating thinner shims.

This leaves the mystery: if your engine hasn't suffered lubrication failure (extreme and visible wear on the cam and follower) and if it's running well, just noisy (meaning you have compression, meaning there's not some bit of crud holding those 2 valves open) then why the big clearance?

(Such lubrication failure would likely not just affect 2 valves.)

A possibility: you're not the original owner. Do you have the service records? Was the head removed and the valves worked on before? What a machinist might have done, after re-cutting a badly burned valve seat, is find that now the replacment valve is too high or far into the head so that no shim is thin enough. The machinist then shortens the valve stem. Presumably a skilled machinist adjusts the stem's length so that a shim somewhere in the middle of Toyota's range of shims is correct.

And now the reveal: what if the machinist took off too much?

I was thinking pretty much the same thing.

As for shims on both sides of a bucket, I'm not aware of any manufacturers doing that. As it would just be introducing needless complexity.

Now a special thicker bucket or shim could be machined, but before I did that, I'd pull the head to find out exactly what I was dealing with.

 

[ajonesnv]

The service records from the previous owner is spotless and he took great care of it, so I think I will just make up the difference with what Toyota offers and live with the noise until there is a legitimate failure. Like I said, all the functionality is that of a perfect truck, it just happens to be loud.

 

[Kryptoroxx]

There's the picture from when I did my valves. I have the 3rz but they are the same shims if I am not mistaken.

 

[ajonesnv]

There's the picture from when I did my valves. I have the 3rz but they are the same shims if I am not mistaken.

Yes they are.

 

[gamefreakgc]

The service records from the previous owner is spotless and he took great care of it, so I think I will just make up the difference with what Toyota offers and live with the noise until there is a legitimate failure. Like I said, all the functionality is that of a perfect truck, it just happens to be loud.

What are your plans for the vehicle? Are you planning on getting a new one/new engine eventually or keeping it for the long run? If you are hoping to make it last you will have to make the repair eventually, either repairing the valves now or after you've burnt the valves with more damage.

Also, a stuck open exhaust valve will also eventually throw a code. It's allowing unburnt fuel into the exhaust and messing up the O2 reading, causing the engine to run lean. The unburnt fuel will also cause pre-mature cat failure. Ask me how I know all this

 

[ajonesnv]

What are your plans for the vehicle? Are you planning on getting a new one/new engine eventually or keeping it for the long run? If you are hoping to make it last you will have to make the repair eventually, either repairing the valves now or after you've burnt the valves with more damage.

Also, a stuck open exhaust valve will also eventually throw a code. It's allowing unburnt fuel into the exhaust and messing up the O2 reading, causing the engine to run lean. The unburnt fuel will also cause pre-mature cat failure. Ask me how I know all this

I would agree, however the engine is operating as intended. No CEL's and no signs of abnormal operation in those two valves and bear in mind this has been this way for almost 100,000 miles.

I will be keeping the truck FORE-V-E-R. In the long run i have no problem getting back into the engine. As it sits now the thought of pulling the head isn't a "well since Im in here Ill do it" possibility. This would entail pulling the whole front so that I can free the cams (if I understand the intake valves correctly). Since it is my daily driver I have to get it back together in a reasonable time frame.

 

[KidVermicious]

What are your plans for the vehicle? Are you planning on getting a new one/new engine eventually or keeping it for the long run? If you are hoping to make it last you will have to make the repair eventually, either repairing the valves now or after you've burnt the valves with more damage.

Also, a stuck open exhaust valve will also eventually throw a code. It's allowing unburnt fuel into the exhaust and messing up the O2 reading, causing the engine to run lean. The unburnt fuel will also cause pre-mature cat failure. Ask me how I know all this

x2 to all this. If you're going to drive it into the ground and pitch it, drive away. If you like the truck and would prefer it stick around a while, you'll be money ahead to tear into it and make things right now before whatever is wrong has a chance to make other things wrong.

And on edit, since we simulposted, find a cheap beater to last you the winter and get to wrenching.

 

[gamefreakgc]

I would agree, however the engine is operating as intended. No CEL's and no signs of abnormal operation in those two valves and bear in mind this has been this way for almost 100,000 miles.

I will be keeping the truck FORE-V-E-R. In the long run i have no problem getting back into the engine. As it sits now the thought of pulling the head isn't a "well since Im in here Ill do it" possibility. This would entail pulling the whole front so that I can free the cams (if I understand the intake valves correctly). Since it is my daily driver I have to get it back together in a reasonable time frame.

Ahh, I have been there too. I did a valve job on my 91 over a weekend (included having to special order the shims) when it was my dd and just about pulled my hair out. Probably the hardest engine I have ever worked on.

If you can get a loaner car or a rental or something for cheap it makes it way easier but if you cannot it makes total sense. You're already aware the problem is not going to go away, so perhaps in the near future you'll have a better scenario to get the work done.