1uz head gasket install

[spf_lexus]

Just after reaching 200,000 miles I supercharged my engine and about 1,000 later my head gaskets went... and it was at sustained high rpm. I slowed down to notice the leak was temporarily sealed, just to leak again once I revved high.

I am down to my head studs and exhaust manifolds and am about to try something different about taking off the scary-to-mess-with headers.



I plan on unbolting my cats at the header flange and pull the head w/ header as one piece. I cant find anyone who has tried this but from the look of it there's plenty of room.

 

[XR8tt]

Hope your hands are clean? Now you've come inside on P/C lol..
Yea I guess whatever is the easier..
Your going to mill heads and fit some MLS / Cometic head gaskets??
Get thicker if you can... If head bolts are TTY you MUST replace them !!

 

[spf_lexus]

I have a set of cometic MLS gaskes and ARP head studs as well as cam seals coming from Lextreme. I will most likely end up re-surfacing my heads too but I guess its not quite necessary? Oh well better safe than sorry, dont want to do this twice! My entire garage floor is littered w/ parts and labeled bags of bolts.... want to do this right since its my first time cracking into a 1uz.



Hey XR8TT- I have standard comp coming and didnt feel it was completely necesary yet, until I replace my pistons and seals later on i'm not going any higher than 7-9psi.... (for now).


Yeah these stock headers are a mess and even the stock cat bolts wont cooperate. the top 3rd bolt for the cat (one thats unreachable w/o 2 long extensions) is rounded so I am cutting the driver side cat up high at the flange and will mark and re-weld for install. Frankenstein maneuver but it works.

 

[RedPhoenix]

damn that sucks. is that all you broke though?

 

[spf_lexus]

Well who knows but im fairly confident my driver side gasket is bad, just took off the passenger and it looked ok. I had oil dripping from driver side anyway. I plan on replacing virtually every gasket I can. Basically im leaving the block mounted and pretty much everything bolted to the block needs to come off.... very time consuming process, 2 solid days so far just to get the heads off. I want to take my time and learn as i go (I have never tore an engine apart in my life) but its been sorta fun going.:lmao:

 

[spf_lexus]

The driver side came out after unbolting the header..... to do that I needed the head to already be unbolted and movable. I zip tyed the head inward as far as i could and then I had access to the last bolt. Getting the heads resurfaced and guides swapped out also. Anyone feel i should replace the spark plug tubes?


Here's a list of the replaced parts coming, if you see some major ones I dont have its probobly because i have already done it.

MLS head gaskets
ARP head studs
waterbridge gaskets
upper/lower plenum gaskets
camshaft gaskets
header gaskets
cat gaskets
motor mounts
valve guide seals


Anything out of the ordinary I should take a closer look at? I was thinking spark plug tubes, I saw some oil collected in the bottoms of 2 or 3.





Also, does anyone know what the ARP head studs should be torqued to? Can I get away with a little more torque? I hear its around 55lb but can't verify. anyone know what a good torque for a FI engine should be?

 

[stevechumo]

...Anything out of the ordinary I should take a closer look at? I was thinking spark plug tubes, I saw some oil collected in the bottoms of 2 or 3.

You should have them replaced. I have most of the gaskets replaced before I plan on boosting.

...Also, does anyone know what the ARP head studs should be torqued to? Can I get away with a little more torque? I hear its around 55lb but can't verify. anyone know what a good torque for a FI engine should be?

I think the ARP head studs should be torqued as usual. My repair manual says the 1st torque is 29 ft/lb, next is 90 degree turn. If you have time, adjusting valve clearance will be great. I'm thinking about doing this, too.

 

[spf_lexus]

29lb? Im using cometic MLS gaskets, they only require one torque. I wonder what would be the problem w/ torquing to 60+ lb?

 

[stevechumo]

29lb? Im using cometic MLS gaskets, they only require one torque. I wonder what would be the problem w/ torquing to 60+ lb?

The reason to have 2 steps of torque is to make sure the head face is evenly torqued. The final torque (90 degree) will make sure keeping the head down for good. I'm sure you know the sequence when removing and reinstalling the head. If you just torque 1 time, I'm very positive the head won't seat evenly against the block. This will have a chance for the head to be warped and leaked. The 2 steps sequence is just not for the 1UZ, it's applied on all cars from what I know. The 29 ft/lb and 90 degree torque is what I took out directly from the SC400 repair manual.

 

[spf_lexus]

Do i have to drive it for a certain distance and then tear down and torque again? Or do I just torque to 29 and then torque to max after? This is my 1st time and a quad cam probably int the best to learn on but i have no choice. I just got my valve guide seals swapped and ALL the rubber was deteriorated and that explained my slow oil consumption. and am taking the heads to a machine shop for a re-surface + shim adjustment tomorrow morning.


Steve can you tell me more about the 2 step method? i was planing on "star" pattern the head to 29 evenly and then re torque to max after the 29 has been evenly seated. I have read extensivly that OEM gaskets require a re torque after xxx numer of miles. MLS states only 1 torque required.

 

[stevechumo]

You got it, my friend. It's the star pattern or the "X" pattern. The heads need to be torqued from the center out and crossing over to the other side. The pattern will become the wider X everytime you cross over to the other side. I'd trust the factory recomendation on torqueing the heads back, because it makes more sense. The first 2 heads (left & right) are for removal and the bottom 2 heads (left & right) are for installation.

 

[XR8tt]

The reason 90* is used ? If thread is a little tighter on one more than another. You'll get uneven torque settings.. If you use oil on some and and non on others. There's close to 1/4 turn difference...
Much much easier on torque wrench also.. I use a 1 metre bare over breaker bar.. Ya have to get a little cunning as you get older !!!

 

[Lextreme II]

Check ARP recommendation for 10 mm studs. Its on the package. ARP give two torque specs. One with ARP moly grease and one with conversional oil.

 

[stevechumo]

I don't know the recommended tq if it's 60 ft/lb like you mentioned or not. But if that's the case. You may torque to 30 ft/lb for the 1st time for all of the head studs, then 60 ft/lb to finallize it. This is to make sure the torque is applied evenly to the whole surface.

 

[spf_lexus]

gotcha! thanks Steve. Looks like this 1uz engine is getting a complete overhaul minus the block.

Just replaced my valve guide seals and took my heads to a machinist to get them resurfaced and he said I had 40% pressure loss, thats quite a bit. I am getting them a valve job along w/ the seals. Also I just got my motor mounts replaced and guess what? they were both split in half! The engine was "resting" on the mounts. I also have these gaskets to replace wheni get them back:

valve cover gaskets
spark plug gaskets
cam gaskets
header gaskets
plenum gaskets
water bridge gaskets
cat gaskets

Basically my whole garage looks like a chop shop, stuff everywhere.

 

[stevechumo]

You're welcome, buddy. Yep. It's a complete overhaul. I'll do the same to mine. I'm not sure how the machinist know it's 40% loss. :aargh4: Is it a good guess? Did he put the head on a flow bench and test it out? But resurfacing it is a good idea anyway. I'll just get the gauge to measure mine. If it's bad, then I may take it to the machinist. If not, I'll keep it that way, which I hope.