How long does it take to develope symptoms of burnt valve?

[Pyral]

I finished measuring the clearance on the valves on 3rz-fe and the news is not good. Every exhaust valve was .003-.006 (.01 is the lowest it should be), the intake valves were slightly better with only 4 being below .06, and most others falling borderline in spec.

I never had misfires, sever vibrations, rough idling which are signs of burnt valve. Any way to know how much damage has been done?

 

[brillo_76]

What's the compression values of the cylinders? What's the leak down tests show?


If you has some clearance and just out of spec. The valves should be fine. I would suspect that if the valves were not sealing you would know by engine symptoms.

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[Pyral]

Once everything is back together I'll do a compression test. Doing the valve adjustments was a good idea, otherwise I'd be spending several thousand down the line to have my valves lapped or replaced.

.003 on the exhaust seems quite bad. Of course its the very rear cylinder that is a pain the the ass to remove too, I wouldn't want to remove it either. Can I remove the cam shaft to get the shims out, how hard is it to get the camshaft back in correctly if I removed it?

 

[phattyduck]

Once everything is back together I'll do a compression test. Doing the valve adjustments was a good idea, otherwise I'd be spending several thousand down the line to have my valves lapped or replaced.

.003 on the exhaust seems quite bad. Of course its the very rear cylinder that is a pain the the ass to remove too, I wouldn't want to remove it either.

But you still HAD clearance. Which means the valve was fully closed during the ignition stroke. I'd suspect something else.

Still worth a compression test though...

-Charlie

 

[Pyral]

But you still HAD clearance. Which means the valve was fully closed during the ignition stroke. I'd suspect something else.

Still worth a compression test though...

-Charlie

I never had an issue, this was done as a preventative step since I didn't know when it was done.

Also I read that you shouldn't rotate the crankshaft without a shim in place since the edge of the valve bucket can mar the cam lobe. I don't see how I can possibly avoid doing that since I need to reposition the cam lobes to get access to different shims.

 

[JZiggy]

I never had an issue, this was done as a preventative step since I didn't know when it was done.

Also I read that you shouldn't rotate the crankshaft without a shim in place since the edge of the valve bucket can mar the cam lobe. I don't see how I can possibly avoid doing that since I need to reposition the cam lobes to get access to different shims.

Have to do one at a time unless you take the cams out. Pull, measure, and if you don't have the one you need, replace, then do it again later when you have the shim you need.

 

[brillo_76]

The clearance us the key. If you had zero clearance then your valves could be slightly open.

Nothing wrong at all with adjusting your valves. I just wish they make it simpler to do as getting to those buckets can be a challenge.

P.s. its always a good idea to do your compression test etc. Before you take the engine apart. So you can compare numbers abs results before and after...

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[chapolito]

I adjusted my valves a couple months ago and had similar — .0025 on exhaust #4, way tighter than the others. Wonder if that is common (and why) or just coincidence?

 

[19963.4lsr5]

The valve seats ware over time causing the valve to go deeper into the seat which in turn shows as less clearance.


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[Pyral]

I adjusted my valves a couple months ago and had similar — .0025 on exhaust #4, way tighter than the others. Wonder if that is common (and why) or just coincidence?

I want to say that its common because its a giant pain in the ass to remove any of the shims from cylinder #4, and nobody wants to do it. Especially the rear intake shim on #4, the heater hoses get in the way and its so far away from where you stand.

Pulling the camshaft might of been better since I have to remove 14 of the 16 shims anyway.

 

[JZiggy]

I want to say that its common because its a giant pain in the ass to remove any of the shims from cylinder #4, and nobody wants to do it. Especially the rear intake shim on #4, the heater hoses get in the way and its so far away from where you stand.

Pulling the camshaft might of been better since I have to remove 14 of the 16 shims anyway.

This might help with the rear ones

https://www.toyota-4runner.org/3645055-post456.html

 

[chapolito]

Definitely that back exhaust one was a major PIA. I finally got it by:

1. Use the Kawasaki motorcycle valve tool to start levering/depressing the bucket. (learned of this tool from this video: https://www.youtube.com/watch?v=pKEkOdQuJR4&feature=youtu.be)
2. Disassemble the schley tool and just use the depressor side to wedge it open.
3. Might need to go back and forth between each tool.

Still took me an hour for that single valve. I had to replace 12...I'm definitely looking at removing or loosening the cams next time.

 

[Pyral]

Have to do one at a time unless you take the cams out. Pull, measure, and if you don't have the one you need, replace, then do it again later when you have the shim you need.

Should of done that. I tried shoving feeler gauge between the cam lobe and the shim bucket, rather than the cam lobe riding up the feeler gauge like a ramp, it chipped a rice sized piece of metal from the shim bucket.

Does anyone know what Toyota calls the shim bucket?
And do I have to pull the head to replace the shim bucket?

 

[chapolito]

I want to say that its common because its a giant pain in the ass to remove any of the shims from cylinder #4, and nobody wants to do it.

The valves have never been adjusted on my engine. :noidea:

 

[brillo_76]

Should of done that. I tried shoving feeler gauge between the cam lobe and the shim bucket, rather than the cam lobe riding up the feeler gauge like a ramp, it chipped a rice sized piece of metal from the shim bucket.



Does anyone know what Toyota calls the shim bucket?

And do I have to pull the head to replace the shim bucket?

Tim has a video on how to replace the shims.
You going to have to pull the camshafts to replace a bucket.

The heads can stay on.

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[Pyral]

Tim has a video on how to replace the shims.
You going to have to pull the camshafts to replace a bucket.

The heads can stay on.

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Yeah, its a giant bummer that I got so far and was on the final shim when it happened. I think the part number for the shim bucket is 1375174020, Toyota calls it an engine camshaft follower for some reason. Costs about 20$, luckily (relatively speaking) I only need one.

I didn't want to remove the camshaft, but now I am gonna to replace this bucket and its not even going to save me any time since all the shims have been removed on the exhaust side.

I think if you have to replace most of the shims then removing the camshaft might be a good idea if you feel comfortable with it. For 1 or 2 shims removing the camshaft is dumb.

 

[gamefreakgc]

A note on burned exhaust valves - I usually see them closer to 300K miles. Toyota valves are stout but they don't last forever and will start to develop 1/4 inch hairline cracks which eventually become "chips". A compression check will tell you if you've got a burnt valve as we rarely, and I mean RARELY have compression leaking past the piston rings. It's the closest thing you can get to a guarantee it's the valves.

 

[brillo_76]

Yeah, its a giant bummer that I got so far and was on the final shim when it happened. I think the part number for the shim bucket is 1375174020, Toyota calls it an engine camshaft follower for some reason. Costs about 20$, luckily (relatively speaking) I only need one.



I didn't want to remove the camshaft, but now I am gonna to replace this bucket and its not even going to save me any time since all the shims have been removed on the exhaust side.



I think if you have to replace most of the shims then removing the camshaft might be a good idea if you feel comfortable with it. For 1 or 2 shims removing the camshaft is dumb.

I miss the old valve adjustments but they weren't overhead cams on the 22r up to the mid 80s. All you needed was a screw driver. 12mm wrench and your feeler garages.


Those days are gone. Major bummer on the chipped bucket..

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[brillo_76]

A note on burned exhaust valves - I usually see them closer to 300K miles. Toyota valves are stout but they don't last forever and will start to develop 1/4 inch hairline cracks which eventually become "chips". A compression check will tell you if you've got a burnt valve as we rarely, and I mean RARELY have compression leaking past the piston rings. It's the closest thing you can get to a guarantee it's the valves.

Oh good to know. As my one engine is at 280k. I guess when I do the valve pan gaskets. I be checking my compression and doing the valve clearances as well.

As was wondering were the a good rule of thumb is. Thanks.

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[gamefreakgc]

Oh good to know. As my one engine is at 280k. I guess when I do the valve pan gaskets. I be checking my compression and doing the valve clearances as well.

As was wondering were the a good rule of thumb is. Thanks.

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Of course these being Toyotas, they will run just fine with burnt valves. Just a loss of power. I ran my last engine for years with 60 PSI of compression due to bad exhaust valves, kept on truckin'.

I parted out an engine with 313K on the clock with two absolute destroyed exhaust valves (cylinder 6) and it still ran fine until another issue killed it.