Valve spring retainer disappeared

Hello, folks! Here is a head scratcher for ya... 2000 tundra with 2UZ-FE that lost compression on one cylinder. Got the head off and found the keepers on one valve spring retainer had disappeared. The suspect exhaust valve slightly contacted the piston (#6) and was bent in the process, which kept it retracted far enough that no major damage occurred otherwise. Anyone heard of or seen this? I can't figure out how that is even possible. The retainer keeper halves are no where to be found!

 

Welcome from OKC!
@shifty` would be who you should converse with. Standby...

 

I suck at visualizing stuff like that and would rather tag @empty_lord who has seen far more Toyota internals than me.

What I can tell you is, the 2UZ-FE *is* a low interference engine, and there's a solid chance some dumbass who had it before failed to change the timing belt on the recommended interval (9yr/90k) and threw the belt? If it was in the 4-digit RPMs when that happened, there was likely contact.

We've seen at least one case of a stuck valve with the 2UZ-FE, but I'm not sure that's what's at fault here.

 

Sorry to hear about your troubles. The keeper halves are small and were likely flushed down into the oil pan below, or stuck somewhere in between in an oil galley / passage.

 

Yeah the keepers are there, but I think OP is asking more of why did the failure occur or has anybody seen it somewhat frequently aside from timing belt failure. For example, maybe that valve just got a chunk of carbon stuck in it while closing.

 

His original post says keepers are gone, where did they go, how did it happen.

 

I only see one question, and it's vague. As a first gen guy, have you seen bent valves without timing failure?

 

Nope

 

Bent valves was secondary to missing retainer. So really this is a missing retainer inquiry. Haven't seen that either. We have very little to go on from OP, so it's all conjecture this point.

 

It was running fine before a major miss and ticking horribly started. Timing belt had been replaced a few years ago. Timing marks were all in line when disassembled too. My guess is the valve stuck somehow, but I can't picture the keepers coming out.
This tundra belongs to a family member, but I have a 3rd gen 4Runner myself. I agreed to do the wrenching on this to save the old guy some money.
I'm considering replacing the valve, and keepers and putting it back together. My concern is what could have caused this, and is it likely to happen on another cylinder after reassembly?
The engine is super clean inside and only has 155k miles.it did sit for several years after the original owner quit driving, but was fine until recently.

 

Does it have much carbon build up?

 

I would check the guide of the bent valve to make sure it isn't cracked or otherwise damaged. This often happens when valves get bent.

If it was stuck open (even a little bit), the loose assembly of the bucket/valve could have possibly caused the retainers to get kicked out. Just guessing here.

Dan

 

Just one valve? I’ve only seen it happen to an engine that was severely neglected. But sludge that managed to get really hard has caused a stuck valve once in a 4.7 I’ve seen.

only other thing I could think of is debris’s got in and the valve closed on it and bent it so slightly

 

I will try to attach photos for reference. I've removed the valve that lost the keepers. One of the buckets won't come out though. I'm thinking one of the keepers found it's way under that bucket and damaged it. They are a close fit, but all the others came out easily.
Anyone seen this kind of issue?

 

Why does that head say 2UR on it. That’s a different engine family.

 

Is the valve spring intact? A weak or broken spring MAY allow the keepers to come off. Once the keepers are off then the valve is of course free to drop down and hit the piston.

Another possibility might be that the computer was altered (tuned?) allowing the RPM to go above safe levels. Spinning the engine too high can overwhelm the valve springs.

Just guessing, but I think an out of time condition would actually force the valve down and that would cause a more severe bend in the valve.

 

You can use a long punch slightly smaller in diameter than the guide and gently drift out the bucket. Condition of this particular exhaust valve system will be critical to being able to use this head again. The fact that the bucket does not simply lift out is definitely of some concern. Let us know what you find out.

Dan

Edit: Looking at the pictures again the valve with the stuck bucket isn't the valve that lost the keepers is it? So the stuck bucket is over another exhaust valve?

 

Who changes the oil? I cringe thinking about lube techs and the possibilities.

 

Yes, the stuck bucket is over another valve. The valve spring of the bent valve is intact, as is the retainer, shim, and bucket... just no keepers.

 

Yikes. I'm not sure what your options are in attempting to remove the stuck bucket. Outside of a super-strong magnet or some sort of industrial strength suction cup, I'm not aure how one could approach this. But the reason it is stuck obviously needs to be fully investigated as to cause.

Also, the ding on top of the piston that got hit by the exhaust valve does not appear to have twisted the con-rod (which often happens). My guess is there is no need to pull the pan and remove that piston assembly for inspection, but that is just a guess on my part.

Dan

 

Drill thé bucket. Slide hammer it out.

 

If you have a welder available you can just tack a nut on the bucket to pull her out.

 

They are hardened, I doubt any drill would touch it.

Dan

 

Yes I know, not easily at least. That's one reason I suggested welding a nut on it. That said, tapping it down a few times might also get it free.