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Discussion Starter · #1 · (Edited)
About a year ago I installed an MWR Stage 3 shortblock (2ZZ) in my car, which included ARP head studs. Shortly after installing the engine, I started having overheating issues. This would occur only after prolonged full throttle pulls on the highway. During normal driving, I noticed the coolant level go down several times, but at the time I attributed it to air working its way out of the cooling system. My efforts to diagnose this problem are detailed in this thread:

http://www.newcelica.org/forums/showthread.php?t=226372

Just recently, I pulled the cams on my engine and retorqued the cylinder head. I found that every stud broke loose at 50 ft-lb. I ended up re-torquing the head in stages: 50, 60 and finally 70 ft-lb. Since then, my cooling issues have been solved. Over about 1000 miles, I have had no drop-off in coolant level. It turns out that as MWR suspected, my cylinder head had lifted, allowing exhaust gases into the collant passages, which built a big air bubble, stopped coolant flow and overheated the engine.

Apparently, other people who are very experienced with engine building have encountered identical head lifting issues with ARP head studs. The following is taken from NoShoes, a very experienced member of the MR2 Owners Club who has built numerous 3S-GTE engines and has a reputation similar to Boosted2.0 on this site. I've changed the head bolt pattern picture to the one for the 1ZZ/2ZZ. I've also added a few of my own steps that pertain only to the 1ZZ/2ZZ and the fact that you need to remove the cams to do this job:

I've noticed over the years that MR2 enthusiasts do not take the time to retorque their ARP studs after engine break-in.

During the break-in period, the engine heat cycles, there are many vibrations that move things around, and other things that move the studs in the block. You have to re-torque the studs after this period, mainly to make sure the studs are seated in the block properly. If you do not, the head will eventually lift, and you'll get combustion gasses into the coolant system, overheating the car.

Here's what you do to keep this from happening:

1) Remove the valve cover.

2) Clean the cam chain and sprockets with a rag and a bit of solvent to remove oil. Take a bit of nail polish and mark the chain and sprocket on both cams.

3) Remove the accessory drive belt.

4) Remove the tensioner shock piston that goes between a stud on the cylinder head and the main tensioner arm.

5) Remove the cam chain tensioner from the front cover on the firewall side of the front engine cover.

6) Remove all the cam caps and both camshafts.

7) Refer to the factory torque sequence (starting in the middle and working your way out in a criss-cross pattern just like you torque your wheels down), and work on one stud at a time. This torque sequence is shown below.



8) Break loose the first stud using a breaker bar.

9) Remove the nut completely. (A magnetic pick up toll works wonders!)

10) Use an allen key socket (A handheld tool just doesn't cut it here.) to bottom out the stud in the block.



11) Make sure the nut is cleaned, and liberally apply ARP moly lube (not oil, not multi purpose grease, but ARP moly lube) to the nut.

12) Torque the nut down to 65 ftlbs. (Not 70, not 75, but 65ftlbs)

13) Move to the next stud/nut combo in the torque sequence.

14) Repeat steps 7-12 in the correct torque sequence until you have done them all.

15) Reinstall camshafts. Line up painted marks you made in Step 2. Refer to the procedure below.



16) Reinstall cam chain tensioner. Refer to the procedure below.



17 ) Reinall tensioner piston, accessory drive belt and valve cover. Valve cover torque 8 ft-lb.
 

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do you need to retorque if ur using stock studs?
 

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Discussion Starter · #8 ·
Smaay said:
I torqued my head to 75 right off the bad. never had any issues. i torqued the Supra head to 90.
Some people may not ever have problems. After all my problems, I'd say that I would retorque the studs after initial engine run. The couple hours work is worth not worrying about dealing with what I did. FWIW, ARP says right in their FAQ that you need to retorque the studs after initial engine run.

I noticed also that you torqued to 75 ft-lb. The instructions on the studs are pretty adament that you not exceed the recommentation of 50 ft-lb, which I did not. When I re-torqued, I went to 70 since the initial job didn't hold.
 

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Discussion Starter · #11 ·
youngxlos said:
glad i didnt get the ARP studs for my build. great info
MWR threw them in for free after massive delays with my block. In hindsight, I wish they wouldn't have :thumbdown

For the power I'm making, I frankly can't see what is wrong with the factory bolts? :confused:
 

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Jesse IL said:
youngxlos said:
glad i didnt get the ARP studs for my build. great info
MWR threw them in for free after massive delays with my block. In hindsight, I wish they wouldn't have :thumbdown

For the power I'm making, I frankly can't see what is wrong with the factory bolts? :confused:
That's what I'm going to use. What's your car putting down, Jesse?
 

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Discussion Starter · #13 ·
jlitman said:
What's your car putting down, Jesse?
No idea right now. Its on a very conservative map right now while I was trying to solve the overheating issue, plus its only running around 7 psi, which is way low considering my pistons. My boost controller is broken, thanks to some fvcking bastrad on this website that sold me a broken one. I'll be buying a new one soon.
 

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Sorry you had so much trouble with ARP. they have been nothing but fantastic for me. in ARP defence, they are reuseable, and cost much less that OEM bolts.
 

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Jesse IL said:
jlitman said:
What's your car putting down, Jesse?
No idea right now. Its on a very conservative map right now while I was trying to solve the overheating issue, plus its only running around 7 psi, which is way low considering my pistons. My boost controller is broken, thanks to some fvcking bastrad on this website that sold me a broken one. I'll be buying a new one soon.
Ugh -- that sucks. Glad everything else is sussed out.

Smaay said:
Sorry you had so much trouble with ARP. they have been nothing but fantastic for me. in ARP defence, they are reuseable, and cost much less that OEM bolts.
They're cheaper? I didn't know that -- I thought I was saving money going with OEM... huh, go figure :confused:
 

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Smaay said:
Sorry you had so much trouble with ARP. they have been nothing but fantastic for me. in ARP defence, they are reuseable, and cost much less that OEM bolts.
APR head studs are excellent .... i hope he sorts out his problems
 

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Discussion Starter · #18 ·
westrock said:
This only applies to the head studs? Not the connecting rod or main caps?
ARP only recommends re-torquing with the head studs, due to the extreme heat at the block/head interface and the tendency of the head gasket to further compress after running the engine the first time.
Smaay said:
Sorry you had so much trouble with ARP. they have been nothing but fantastic for me. in ARP defence, they are reuseable, and cost much less that OEM bolts.
I'm not saying that they aren't good products, its just that I never realized you were supposed to re-torque them. The package does not mention that. I only found that on their website. The factory bolts are at most $20 more for a set and are reusable as well (read the service manual). The thing is, I've never heard of a problem with the factory boolts, so I have a have a hard time seeing the ARP studs as a true upgrade. Kind of falls into that "if it ain't broke, don't fix it" category.
 

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Jesse IL, one thing I did notice you haven't meantened is "thread lock" compound at all. Like for example fly wheel bolts, I use blue thread lock to lock and seal the bolt a bit more, due to the heat friction also vibration. Perhaps the ARP studs need thread lock also to help retainment. ARP studs are alot stronger than stock bolts so should fair up more and last longer. I would advise using thread lock.
 
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