My 93 4x4 pickup lost its 3VZE head gasket at 300k miles, which I thought was pretty decent. Decided to buy a long block and put it all back together. Engine has been really solid for 6k miles until recently when it had some valve train noise developing. Been meaning to pull it apart to check valve clearance but hadn't got around to it yet. Then on the way home from work the noise got significantly louder but still only sounded like top end. But loud enough I didn't want to drive it till I took a look. So pulled it apart tonight and found some puzzling and disturbing things on the passenger side (haven't opened driver side yet). As you see in the pics, the valve shim for the #3 Intake was sitting beside it and is not only completely dish shaped, but wore so thin in the middle that a hole developed and eventually it just got "spit out" of the bucket. And once the cam rotated around, you could see that the lobe is significantly dented and has some rough looking edges.
So I have a few questions:
1. Any ideas what caused this? Besides a crappy rebuild job on the head, which I will concede. Past the warranty period on the long block but I'll call them anyway. I'm trying to figure out if the cam lobe was just rough and chewed up the shim? Or did it get spun out of position and was being smacked in a weird way causing this deformation?
2. What to do? Would you put a proper shim in it and send it? Or is that cam way too far gone?
3. If I need a new cam, should I just pull it and replace with a good polished one (with proper shimming of course)? Or should I just pull the head and send off for rebuild? As you can see, it is still really clean and I've had no other issues, so I hate to pull the thing if there is a better repair path.

For what it is worth, I still have my old motor that blew the head gasket, so I have access to both heads, camshafts, etc. I could harvest those parts if necessary. I will definitely hold onto the shims!


Notice the shim just sitting there on the head, dished out and with a hole in it? Worn completely through in the center.

Notice the dented lobe and rough edges.

Showing empty bucket under the dented cam lobe. Bucket actually looks good.

 

I've never seen that before. My first thought is the lifter or valve is stuck, or at least sticking enough to offer excessive resistance. Would a shim that is way to thick cause that?
I'd replace the cam, but maybe before you remove it try adjusting that valve to spec. with a new shim. Then rotate the engine by hand and watch what it does.
No codes were stored?
I don't think the cam caused the problem.

As a side note, I'd be more confident with sourcing a decent used oem cam than a new aftermarket one. I think the aftermarket cams have their own separate issues.

 

Thanks, Jimkola. Without the shim in place I rotated a couple of times and the bucket seems to move pretty freely up and down. But I will grab a shim and put it in place and see how close I can get it to a reasonable spec. I wonder if the initial clatter I heard was just excessive gap and then it flung it into an awkward position or something? Really weird. Or did the builder use a shim of questionable metallurgy? It just wore out that shim till it made a hole. Crazy. Check out these pics:

 

Sure would be nice to know if the rebuilder used an aftermarket shim source. Odds are they would be from China, and that could call into question their durability. That's the reason I'd chose a used OEM camshaft over a new aftermarket one.

I don't think that valve was loose from the get go. It would have been pretty noisy. At least loud enough for you to wrinkle a brow.

If it was due to a poor quality aftermarket shim you'd think that other valves would be suffering varying degrees of the same wear. Granted, you can bounce shims around, an ultimately not need to replace all of them, but if the heads had been rebuilt, including the seats, you'd think that they would have needed to replace many more shims than as if it were just a regular adjustment.
You can replace the camshaft, redo the valve adjustment, and monitor it like I did when i got a bad cam and had to replace(got used oem from wrecking yard). I pulled the valve cover probably half dozen times over the first few hundred miles to monitor the wear.

And yeah, unfortunately the cam looks beyond salvage. It looks like the hardened surface has been worn away, and the underlying metal, which is softer, will wear fast.

 

Thanks for the follow up. This was a rebuilt long block that I purchased and it only had a 6 month warranty (I’m at 1.5 yrs now) but I will be sending them pics and asking questions regardless. Gonna wait till I pull every shim from both sides and inspect first.

I still have my old engine so I have access to the cam from that one. Not sure how to check if it is serviceable, but maybe a machine shop can test it out? If it is no good I will try to find a used one somewhere. But before I do that I will check to see if a shim from another bucket will test remotely close to spec. If there is a serious valve issue I am wasting lots of time trying to fix this with the head on. I feel like valve is ok because it had a good compress check a couple thousand miles ago and the spark plug doesn’t look any different from the others (this is on intake valve).

 

You can do a decent visual check of your old cam. Clean the lobes up with some 0000 steel wool or 3000 wet/dry using a light oil and you should be good to go. If you have the old engine then you have a plethora of shims. We reused shims all the time at the dealer.

 

I had to get a couple shims that I didn’t have (didn’t want to grind). But almost ready to go in with another cam. I cleaned up my old one and curious if this is good to go or if I should be concerned. Couple of dings on outside edge of two lobes. And some scoring and staining on some bearing surfaces. Send it? Is this OEM one better than a brand new DNJ CAM950R? Pics are after some light work with 0000 steel wool to get old oil varnish off and soaking in oil until I decide to use it or not.

 

I'd use a used oem over a new DNJ all day long.

 

Took me a while to get a couple of shims in from the dealer and then have a full day to get it done, but I was able to clean up my old 300k mile cam shaft and use it in place of the one that got boogered up. Cam journals and lobes all measured in spec and looked okay, so went with it over an aftermarket. Journals/bearings on the head didn't look wonderful, but should be fine. Just a little scoring in a few places. Got it all buttoned up and now she runs about as quietly as one could expect out of a 3VZE. No more hammer Adjusted all valves to spec on all 6 cyl (put them all on high side of spec for exhaust valves) and only had to order a couple of shims to get it there with some rearranging. Learned some tips along the way that I have not seen posted here or anywhere else that will make a valve job WAY easier if I ever have to do it again. Maybe I'll write that up some day. Hope I have some useful pics.

Anyway, drove it to work this morning and all is well. In fact, she runs a TON smoother all through the throttle range. That one intake valve not opening completely made for some really erratic throttle response and jumping around at different points. Also can't help but wonder if the lack of a shim and the hammer effect that ensued could have tripped the knock sensor, causing erratic loss of power as well? Who knows. Hope it stays this way for a while whatever the reason. I like the smooth response and I like having my truck back.

Thanks to all for your comments and your help. I'm gonna save that shim for the wall of shame. Still makes me scratch my head how it got that way.

 

Nice work! And the follow up is much appreciated.

We found the biggest change to the valve adjustment was the first one while the engine was going through break in. And going tight was far more common than loose. the next time you need to adjust the valves if you shim it so it's centered within the min/max you'll see very little change after that.
Glad your OEM cam worked out. there really is no substitute.

 

Not likely; the knock sensor doesn't "trip."

How do you set ignition timing? What you want is for it to be advanced as far as possible; just to where it starts knocking, then back it off. Old-school centrifugal and vacuum advance were just approximate, and definitely open loop. If you had a 1908 Model T, a lever on the column allowed you to constantly adjust the timing, with your own ear forming the closed-loop system.

Well, you can't get column-mounted timing adjustment anymore, so your Toyota replaces your ear with a knock sensor. The ECM advances the timing until it "hears" knocking, then backs it off a hair. Over and over. What happens if the knock sensor "goes deaf" (e.g, disconnected)? Advancing the timing blind would risk blowing a hole in a piston! So out of a surfeit of caution, when the ECM loses track of the knock sensor, it dramatically retards timing "just to be sure." And it throws code 52 so you know why it's running like poop.

52 is a stored code, so even if the racket in your valve train somehow masked the knock signal (making the ECM think the sensor was gone), you'd get the code and it wouldn't go away until you cycled the ignition.

 

Great explanation, Scope. And I should have been more clear...I was curious if a really loud hammering valve (keep in mind, there was NO SHIM in this one) would be heard by the sensor as a knock and thus pull back the timing. I do not suspect a loss of knock signal, as I never had any stored codes related to knock sensor and it is an OEM sensor and wire replaced when I had this engine out. May not be possible, just trying to understand why it suddenly runs much smoother. It used to lag and stutter a bit at lower rpm and then take off when it hit 2500 rpms or thereabouts. Was just struggling to see how one very out of adjustment intake valve would make it behave so erratically but maybe that was it. At any rate, it is running fantastic now so I have nothing to troubleshoot and am enjoying driving it again!