Ali SC3

iTrader: (10)

Looks like one of my GX's is going to test how well I can swap cylinder heads
I must have Jinxed myself when I told everyone else how reliable they were (I still think they are and this is a very rare occurrence couldn't find another example online).

The 2004 gx470 started misfiring on 8, tried all the normal stuff swapped coilpacks didn't help, new plugs didn't help, changed injector 8 didn't help, so then I decided to go ahead and test the compression figuring it was not something simple... and found 0 compression on cylinder 8

I just did a timing belt job on it and was upset that I might have caused it, but found out it was unrelated, timing is still 100% dead on, no sheared cam pins..etc.. all looks good on that front

pulled off the intake manifold... I know everyone complains about the starter alot, its in a terrible spot but it only took me 2 hours to remove the intake manifold and I was going pretty slow, did drop a 12mm socket into the V of the engine which I later recovered, but yeah not as bad as I thought it would be to be honest I expected it to be worse than it was.


and then the cylinder 8 intake valves, can you tell which one has an issue lol.


this one looks okayish..


this one does not...


still trying to figure out what the mystery metal is, I am guessing its the valve stem seat that broke off, possibly from an old repair job that I am not aware of even. I'll know for certain once I pull the head but thinking I need a replacement cylinder head by the looks of it. Fun stuff but soon I can say I've done the heads on a 2uz. Valve doesn't look bent and was never out of time so I don't think it was the pistons fault.

Kinda makes me more interested in building a spare 2uz now that I have worked on one its not as bad as everyone says it is. I have the non vvti and its actually a pretty simple motor setup except for that stupid crank sensor wire if you don't put it behind the fan bracket when reinstalling the timing belt the accessory belt will eat up the wires, ask me how i know.. lol

will keep everyone updated in case you ever wondered what pulling the cylinder head and replacing it looks like, as well as what the mystery metal is when I can see more of the destruction and post more pics, but I wont be pulling the head till next week doing it in a couple stages. Also going to get the exhaust runners welded up on that side while I have the head off, one of the runners has that famous leaking sound so its kinda lucky it was the same side.

Jacket

Is that the same GX that you bought with the bad transfer case?

Ali SC3

iTrader: (10)

nope, the 2003 I bought with a bad transfer case and replaced it with one from a 2005, and that is still running perfect. not a single complaint with the 2003 at all, and it has been doing double duty since this happened.

The 2004 was running just great since I bought it, but this showed up first as a rough start that went away and then came back a few days later and stayed (felt pretty much like a bad coilpack does), still drove alright on 7 cylinders back home but not the best of course. Inside of the intake is very clean, I can't see any reason for it to have failed like that and the exhaust leak seems to be at cylinder 4 so I don't think that caused it... it is an intake valve after all not an exhaust valve.
The previous owners lack of knowledge on this car did make me suspicious, which is why I changed the timing belt and did a trans flush myself. the guy tried to tell me it has a timing chain...
Belt and WP looked like it has been replaced on time when I took it off the condition was fine and everything was properly timed up, but his comments just made me replace them anyways.

My only guess is that the early year head castings are not as good in some way but I haven't heard of that before. I did notice that there are numbers cast into the side of the head and the newer years have higher numbers on it so maybe they revised them at some point? just a guess.

who knows when I pull it maybe nothing is wrong and someone dropped a piece of metal into the intake at one point.. but I highly doubt it since its perfectly wrapped around the intake valve. Most people would probably be really upset if this happened to them. alot of shops just pull and replace these motors for like 1k installed around here, there are almost always 3-4 2uz's on craigslist around these parts for $600-700 if you shop around.

I actually enjoy pulling and replacing a cylinder head as long as I am not rushed to do so, done it on the 2jz so I have a pretty good idea what I am doing. I would have yanked the engine and replaced with used, but then who knows if it will happen again, and its more costly that way.

tz693

Keep up you work! I really enjoy reading your post on repair.
Good work!

chiph9

I'm curious about the ragged edge on that ring (assuming for now that it's the valve seat).

I'm thinking it may be one of:
1. It was machined improperly
2. Valve lift was too tight (or cam wore) so that valve head would hit it hard
3. Something else

But you (we) won't know for sure until you get in there. Is there a local shop you can take the head to?

Chip H.

Ali SC3

iTrader: (10)

Thanks Tz693, will do just taking it a little slower than usual since motor is still in the vehicle.

Chip, I was wondering about that as well, I hope I can figure it out once I get the head off.
There is a good machine shop around here that works on tons of toyota heads, they do all the landcruisers and I even took a spare 2jzge cylinder head there they did a great job. they can do custom valve work but they are pricey. I will likely just pick up a better condition used head and drop it off for them to clean up. I don't want a repair job that can fail again.

this is the Inline 6 cylinder head they did (2jzge) a clean up that had a blown headgasket, they hot tanke cleaned it, decked it flat, tore down the valves/springs and reassembled with 24 new valve seals. No valve damage so original valves went back in.

Ali SC3

iTrader: (10)

this page has some interesting picture of comparison between the older and newer 2uzfe cylinder heads if you scroll there are lots of pics.
on this one the actual valves cracked up, but this was on LP gas conversion that wont happen on our pump gas.
http://s143.photobucket.com/user/ste..._8669.jpg.html

also has a pic of the valve seat, it sort of does look like there is a ring that can break off there, and that one does have a crack in it.

SC3coupe

iTrader: (4)

Toyota got a lot better with the metal ever since the 90s, they started making high revving engines (4AGE 20V for example), it is unusual to think the head of 2000 era would be "weak" , so we should not think there early = weak, since we are not talking about 1981 vs 1989 here, and on a very low rev V8.

I am thinking it crunched something early in life and cause a fracture that gave out now. How many miles on this one?

Anyway.. that's the starter in the middle of the head..? with all the space under the truck they cannot put it there instead? I guess keeps the river water out.

chiph9

Yes, that's the starter. Nice in that it's protected from the elements. Bad in that when it does go out, it's far more expensive to replace because of the extra labor to get to it.

Notice that Ali SC3 doesn't have the manifold air injector pump (which is also in the valley). He must have put a bypass kit in.

Chip H.

dicer

The aluminum head material is what is cracked. The seats are pressed in usually with a real tight interference fit and that also add the extra stress on the casting as well as heat. Yeah they didn't do their home work on that design too well. The cracks allow the seat to come out easy especially when it warms up.

Ali SC3

iTrader: (10)

Yeah there is something off there, maybe it heated up too much once, or something forieng stressed it at some point like you said. I thought maybe it moved some when I took the timing belt off, but the manual says valve damage can occur when removing the camshaft in the wrong position but not the timing belt unless you crank it over or something which was never done, the valve is not bent.

The head has a lot of miles for sure around 260k on it unless it was replaced at some point. it should go 500k at least this is pretty weaksauce for toyota heads if you ask me, they usually last forever if you don't overheat them, about the worst is usually replacing valve stem seals and checking clearances, hardly are out of spec with the design they use.

I don't have the air injection cause its a 2004 2003-2004 non vvti don't have the smog crap, I love it.

yeah I am guessing I will see a similar stress crack when I remove it, hopefully I'll have time later this week.

Ali SC3

iTrader: (10)

Well I pulled the cams and started removing the valve caps and shims one at a time very carefully... and I think I figured out why this head self destructed.

all the valve caps are supposed to have shims under them obviously (the thing they change when doing a valve adjustment), and well I pulled the 16 caps on the passenger side and guess which one had no shim under the cap at all.... it was intake valve number 8, the one that broke the valve seat.

This really explains alot and now I am more at ease its not a design flaw or common problem, what must have happened is some mechanic pulled the head or cams at some point, and did not realize they dropped/lost the shim on the last cylinder back by the firewall as normally they stick to the bottom of the cap and they go off and right back on. they dont always stick on the bottom though like the number 2 exhaust one came off while I was doing it but I was paying atention and didn't loose it, its not rocket science you know.

the lack of having the shim there means that the valve was closing very harshly basically pounding the valve seat every time it closed, which explains the tapping noise I was hearing and why the valve seat looks like it broke off.

I will confirm with some more pics once I pull the head, waiting on some help to lift it out of there with the exhaust manifold still attached it is a little bulky and seems more like a 2 person job.

I am wondering why they needed to go and remove the cams in the first place, cause thats the only way you can loose a shim under the valve cap, but the car has lots of miles and this could have been done at any time. I know for replacing the exhaust manfiolds the book says to remove the cylinder head, so maybe it has the exhaust replaced a long time ago and that is when the mechanic lost the shim. pretty crappy detail to overlook when putting an engine back together if you ask me but I expected it to be something silly like that.

I picked up a spare cylinder head off a 2003 tundra that is in great shape, so I will be taking it to the machine shop on monday (closed on weekend) and dropping it off there with the cams from my bad cylinder head, so they can install the cams and measure the valve clearances on the replacement head and order the missing shim and any different size ones they need etc.. at this point I dont want o deal with valve adjustments, they are pretty reasonable so I will leave it in their hands and get the valves stem seals replaced so this head will be good for another 200k miles at least.

SC3coupe

iTrader: (4)

That's good you found the root cause to be human error. I searched for 2UZ with this problem on the net but found pretty much nothing on this issue. Tapping noise should be gone. After a new headgasket and valve stems seals you should be good to go to 400k miles or so with the stock block?

Ali SC3

iTrader: (10)

Yeah I am glad I found it as well, I keep searching for missing or lose shim under bucket, and I cannot find 1 other example online where someone forgot to put the shim in, must have been a pretty forgetful mechanic I couldn't imagine making that mistake on someones engine. This probably works well with the "just replace the engine" mentality more and more independent shops seem to have these days.

Yeah already got the headgasket kit with some new headstuds, will clean it all up and slap the refurb'd cylinder head on with new valve stem seals (I always do this whenever I pull a head, valve stem seals with proper oil changes seem to last alright to 200-300k on a toyota cylinder head then you get oil smoke out the exhaust on startups, and eventually leads to it smoking all the time), probably pull the cams on the other side and check all the shims are in place there for peace of mind.

I have no doubt these engine would do 500k easily and I certainly expect it to, they are iron bock motors after all (all landcruiser motors have iron blocks cause they are superior in every way except weight), so that is only breaking them in to me.
my dry compression test showed 180 psi in 6 cylinders, 160 psi on one cylinder on the bad side, and of course no compression in the one with the bad valve but I have a feeling after I get it back together it will be 180 on those last 2 as well, the 160 would have probably gone to 180 also with some oil in it but that was not the one I was worrying about so I didn't bother. as far as my tests go this motor has no internal wear on the important stuff. cam caps look perfect there as there is no scoring etc...

as you said it looks like it was human error. not a mileage or condition thing. I push my '03 all the time been hauling stuff through the mountains and its got 245k on it, idles like butter. my father's v8 4runner had like 60k on it when I used to drive that around and honestly they feel identical power wise and smoothness wise. I am a believer in the 2uz again.. lol, just not a believer in mechanics who loose valve shims, they probably didn't even realize it was a shim under bucket design I bet they just thought it was the newer shimless bucket style found on the prius etc.. they look the same from the top.

95% of the time the shim sticks tot he bottom of the bucket, but that other 5% of the time you have to notice the shim fell out or is missing before you start bolting the cams back in. its funny this stuff always happens to me, I try not to let anyone touch my cars for this exact sort of reason.

Ali SC3

iTrader: (10)

Well I broke my hand so that is the end of this thread....
J/K, well I did break my hand unrelated to working on cars, but will continue with the project when It heals.