puttin the motor back together

[Kennyfvholla]

The tighten sequence is called "Angle Controlled Tightening" which is designed to reliably torque bolts. Not all torque wrenches read the same, nor do they properly allow axial de-straining required to achieve consistent preload. The majority of ACT procedures are designed to bring the bolts very close to yield. In most cases, ACT processes provide less than 5% variation to yield. A slight over-torque makes the bolt no longer usable.

 

If you are the first person to take apart the engine, they are probably safe to use again (assuming they were properly installed). If you aren't the first, or aren't sure, then don't reuse them. If the previous mechanic went just a little too far, the bolts are no longer usable.

 

Best practice is to replace the head bolts every time.

 

 

This is a good point. Thinking about this more, if you don't know the history of the bolts you should replace them. I remember when my engine was overheating and a few mechanic people I know (who aren't exactly the brightest people in the world) a while back, told me to just pull my valve covers and cams off and then torque the heads down even farther and that should help seal up the gasket leak... Being someone with common sense when it comes to cars, I did not do this. Your post just made me wonder how many mechanics and do-it-yourself-ers may have done this to any given Subaru out there in the past. That would definitely render the bolts unusable, as they would be stretched.

 

Hence the following quote.

 

 

yeah i know there reusable and even if they arnt just torque em down alil more and they will stretch a lil tighter. now they can only tighten so far but most motors arnt taken apart enough to match the life of the bolts. ive rebuilt a 79 T bird motor 3 times and the specs on torquing the bolts were 85 ftlbs then 100 ft lbs then 115 ft lbs to a max of 130 ft lbs then get new bolts. this i told by a mech at the dealer.

 

Besides that, a Ford engine from the 70's is completely different than a Subaru engine from the 90's.

[severedevil]

i figured, and because i didnt know the history of the motor i did replace them. i DID replace them. now with the car running Like A Boss today i took it to adv and 3 codes are commin up, cam pos sensor(still wtf) and 2 idle air control sensor codes. now i messed with the Idle Air Sensor and when i touch it theres a loud ringing and it idles rough, then when i let go in abt 2secs it smooths back out. but it still idles at 1200rpms in N and P and 700 in D and R(but rough in D and R, Smooth in N and P). i think the sensor is ok but the pigtails bad.... right? also i rev it to 2k while in N and it drops to 500 stutters and revs to 1200 and idles there...

[bmx045]

Cam sensor eh? Maybe your dumbass friend knocked that out of commission too

[severedevil]

well it runs like a boss so i doubt theres anything wrong with the cam sensor.

[overspool]

is the cam sensor code current or pending? it'll tell you when you pull it with the obd2 scanner.

[johnegg]

Also, applying a little bit of fresh engine oil to the bolt before threading it in is a good practice.

 

this is not just good practice, it is spec. the threads and the washer at the top should all have a coat of new motor oil.

 

i have read the subaru FSM and i am in the do not replace camp. no where does it say to replace the head bolts. it does state in BOLD letters to replace the head gasket, but it never says to replace the bolts. but you should each do what you are comfortable with.

 

in my opinion it is nuts to use anything except subaru head gaskets and of course you do not have to replace the bolts. but there are lots of folks who use after market head gaskets and new head bolts.

 

i would spend my money on the subaru gasket and re-use the bolts. i believe you will have fewer ''repeat failures''.

 

just my opinion.

[overspool]

I wasn't sure if it was subaru spec. I just know that all the Toyota engines I've reassembled have called for it. Thanks for verifying!