Ali SC3

iTrader: (10)

So, I'll update this thread for those that are interested because I ran into an interesting problem.

I adjusted the valve shims, 4 were out of spec, 2 high and 2 low so I ended up measuring and found that I could get them in spec by swapping the shims on the high and low ones, and that brought everything to spec.
Here was my grease stained chart for that.


I then put everything back on and while the valvetrain was much quieter, there was this tapping or thud kind of sound going with rpm, and when I put my hand on the timing cover, I could feel a shock on my hand with the sound, almost like the belt was hitting it (it wasnt belt is perfect still). This was odd to me since there were no misfires and it was running very smooth.

so I tore it down a few more times and thought maybe the timing rear cover was touching, but no it wasn't.
Then I cam across an obscure thread on supraforums about a similar knocking sound and they said it was the cam gear key hole had got wallowed by the cam alignment pin and made the cam gear "loose" and could rotate right or left a mm. that got me thinking right away that could be the issue cause when I put the cam gear on each of the 3 times, I thought it went on a little too easy, normally they take some really careful lining up.

So I once again tore the motor down and removed the cam gear and found that the key hole was indeed wallowed out allowing it to move even though the cam bolt is torqued properly. I believe this is what leads to a sheared cam pin after the cam pin hits the side enough times and then the timing belt skips, I have read a couple 2uz threads where this happened, and I can bet they had this sound before it did and ignored it.
I will be replacing the cam gear this week and updating the thread. pay attention to those cam gears, I should have noticed when I was wrenching on it but didn't catch it till I read about it on the internet, and it was the only thread I could find that documented this problem. every other thread said oh its "piston slap" or valve noises. I think alot of things get blamed on piston slap that could be this loose cam gear issue.

Also to noteI couldn't see the wear with the gear on, the front looks alright, but when you flip it around you can see the indent. caused a couple mm's of play on the cam. scary right.

pics:

SC3coupe

iTrader: (4)

Wow, and your cam pin is ok?

chiph9

I would replace the key as well. And look carefully at the slot in the cam for rounding-off.

Also, this is a bit strange. The parts diagrams at Lexus Atlanta show the pin on the VVTi motor, but not the earlier one.

Chip H.

Ali SC3

iTrader: (10)

Yeah the Cam pin appears to be fine, it seems like its a harder material than the cam gear.
Will know when I put the new cam gear on if there is any play.

Well the cam has an alignment pin sticking out of it, and the cam gear has the slot, its the same as most other non-vvti motors, almost identical to the 2jz cam gear setup.
Sometimes those diagrams are just plain off.

The slot on the cam gear shown above is what took the damage, the pin on the cam seems to be hardened steel and hasn't taken any damage, but I will double check on it. It doesn't wiggle or move or seem out of round at all.

I think the cam gear is regular steel and hence took all the damage, but I am sure if I let the cam gear continue to whack the cam pin for however many thousand miles it would have eventually sheared the cam pin off. lucky there is a parts place about 30 min away that has 4 RH 2uz cam gears so I will pick a good one and see what it does.

I need this engine to run without making any weird sounds already, its starting to bother me I have had the belt off like a half dozen times and its gotten old very quick. at least I think I solved the mystery noise though, fingers crossed.

Ali SC3

iTrader: (10)

Well its still a little bleak on the outlook, the engine runs fine still but there is some sort of noise that has been isolated to the top end cam area. starting to think this head was in worse condition than I thought on the cam journals or possibly the cam I reused from the GX is out of shape or has a flat spot I can't see, sort of running out of ideas. the tapping noise is very rhythmic but not the usual valve clearance noise I am used to.
I took it to my buddies at toyota and the techs thought it could be the cam but they didn't open everything up.

I tried to record it here, you can feel taps along with the noise on the passenger valve cover.

So I tracked down a full replacement head with cams, buckets and shims basically a fully loaded head off a 2004 4runner, so will be taking a look at that and trying to get this engine to run quiet again.

I will start by removing the cams on the current head and seeing how the races look on the head for the cam and see if I can find any damage to the cam. if everything on the head looks ok then I will try the 4runner cams in it. if the head looks rough in any way then I guess I am swapping the whole head out again with the 4runner one and cams. hopefully that will be the end of it tired of buying coolant and replacing components a half dozen times. At least the toyota techs did think it was a cam noise so that gives me hope I can get away with possibly just swapping the cams, although I didn't see noticeable wear on mine. turning into a bit of a headache now I didn't expect to have that issue its not my first cylinder head swap but usually I get them fully loaded. so lesson is likely don't buy a cylinder head without the cams and all the hardware.

6080prado

Why not just get your original head machined? They'll just press in a new valve seat. I'd also get a full valve job, but you'll be back to 100%.

Or was your original head too torn up from the valve seat flopping around?

Ali SC3

iTrader: (10)

The seat was decently broken off and I now suspect other parts like the cam, plus I read that heads with valve seat repair are more likely to fail on the repaired seat in the future than just finding a good head and taking care of it.

There is just a journal surface on the head and the cam caps, there are no actual bearings in the head to replace, once its damaged the head should be junked. you can swap cams people do it al lthe time you just have to re-measure the clearances and re-shim and that is assuming your head is good and not warped. I did also learn that you aren't supposed to mix cam caps from another head so maybe that was part of my problem this head I picked up didnt have the buckets or shims but had the cam caps. I reused the buckets and shims from the old GX head and the GX cam but I even used the old GX cam caps cause they were in better condition, I should have used the cam caps that came with the newer tundra head as they are specific to the head, learnt something new. I did check all the valve clearances but I suspect something else was up there like the wrong caps, bad cam, or a scored cam journal.

I pulled off the cams and the cylinder head cam journal was scored under the 1st intake cam cap, dont know how I missed that before, basically the head is junk, so I removed the cylinder head just too many issues with this one the shop was dishonest when they sold it to me by not telling me about that and me somehow not noticing not really sure how.

anyways I picked up a fully loaded cylinder head complete with cams, buckets, shims everything from a 04 4runner and its in much better shape on the cam journals and caps. going to drop in 100% everything from this head so it all matches and see how it goes. hopefully the noise will be gone it was likely from the cam having space and clicking due to the worn number 1 bearing and using the cam caps from another head. waiting on a new headgasket and then the head will go in and hopefully not make any noises this time around.

keeping my fingers crossed this is my last head swap. I got my hand out of my cast finally so at least things are better/faster on that front now.

Ali SC3

iTrader: (10)

well about half way through got the old cylinder head off and the newer replacement one in place but still need to put everything else back together. good news is I took some pics this time.

block is cleaned and ready for its new headgasket and head


newer replacement cylinder head cleaned up for install as good as I cared to clean it


Headgasket on


Dont have a pic of the head installed but it is currently on and next step is torquing it down etc.. will get around to it later this week.

chiph9

What's that discoloration on the front piston? Just the camera angle?

Chip H.

Ali SC3

iTrader: (10)

a bit the angle and there is some oil sitting on it in that picture, when its wet it looks like a diff color on the camera. the other 3 are dry.

Ali SC3

iTrader: (10)

made some more progress, got cylinder head torqued down, cams installed super carefully, new cam seal, intake in position, power steering pump back on, dipstick back in (super annoying), cam gear and timing belt back on.



things left to do, torque intake bolts, put the timing belt tensioner back in, serpentine belt on, cam cover, and allt he fluids, exhaust bolts, the easy stuff. will likely get it buttoned up tonight and see how its working now... fingers crossed.

Ali SC3

iTrader: (10)

well glad to say I got it all back together and it runs perfect now. no funny noises anymore, pickup is good, everything seems to have gone well.

I did have a bit of a scare when I first started it up there was this loud clanking sound I thought it was the valve shims needed adjusting for some reason. went in there and checked it and all specd out to be dead on, and was confused till I noticed I forgot to remove the Service bolt on the sub cam anti-backlash gear (aka scissor gear). the bolt keeps the spring from doing its thing, and thankfully no damage was done, remove the service bolt and put it together and fired it up and yeah turns out everything was fine just forgot that one step out of hundreds. just happy its all back together now and runs like it should.

tz693

Congrats on your great work!

Ali SC3

iTrader: (10)

thanks. Did I mention I never want to work on the v8 again.. haha, but seriously taking it to toyota next time

Ali SC3

iTrader: (10)

Yeah I understand what you are getting at but that sounds like bottom end work, and they shouldn't have reused those if it had a failure before they were likely scored and should have line honed the whole block etc.. or just replaced the whole block is usually what happens at that point.

this was all top end work and this head that I used was original and had no failure because I had all the parts this time around to inspect. if anything it will make a noise down the road instead of have a catastrophic failure, I personally double checked everything this time around and it is all in spec, the valve lash was nice and consistent all around on the tighter side of the specs. all the cam caps and surfaces were not scored and it all seemed in spec to me.

It is still running well but like you said I have been putting some miles on it to see how it does with an occasional revving it out as well, so far so good. there is a chance my wife may want to sell the car in the near future, so not sure if I will know the long term outcome, but personally I am not worried about it much I have been around enough of these v8's to tell if it sounds happy or not, and this one sounds good to do many more miles.