Right to get this clear, I am not talking about the Intake Plenum Manifold, but the intake manifold that the plenum bolts onto which holds the injectors.

On this intake manifold (made of VERY crappy aluminium) there are 2 studs (one at each end) and 3 threaded holes which attach the plenum to the intake manifold.

Some pathetic ham fisted mechanic did the nuts on the 2 studs and the 3 bolts up sooo tight that they pulled the thread out of the holes and ripped a stud out. They are only supposed to be done up to 18Nm!!!

I have replaced all the threaded holes and one of the studs (the 2nd stud was the only one not harmed) with helicoil inserts and new bolts using 2D (length = 2 times the thread diameter) inserts for better strength. It seems to be working fine and is much stronger than the factory setup.

BUT.... I can get a brand new intake manifold for $75 (Mitsi charges $323). The intention would be to replace the whole lot (2 existing studs and 2 threaded holes) with studs loctited into the aluminium which would be a LOT stronger than the factory design.

Question is... is it worth it? I a not exactly wadding through cash and the helicoils are working, I am just nervous about another mechanic doing gym classes on a socket with a 10 foot bar again...

i wouldn't bother.. it should hold up fine..

buy the sounds of things your not 'illiterate' when it comes to the world of cars.. so you would be saving $$$ buy doing the basics yourself yeh?

Unless the lfange is warped and needs the extra torque to pull down to seal ( major issue!)
i wouldn't bother, by using the heli's with twice the thread bite you'll be fine.

you seem to have done abetter job than most mechanics by the sounds of it.


personally i would get the other manifold and port the life outtait before fitting.... hahahaha

then do the upgrade on the studs next time it needs to come off.

personally i would get the other manifold and port the life outtait before fitting.... hahahaha

then do the upgrade on the studs next time it needs to come off.

LOL I had the same thought :P

I had a look at the stock one and it doesn't look too bad. Could do with a polish, but I don't think porting would do much at all!

You took your Baby to a "Professional"??? Let there be a lesson to all of us...
Enuff of preaching. If u reckon the bolts and helicoils hold ok then it's good. But if u feel uncertain a bit about warping or sealing, use black heat silicon, thin layer, to ensure good air seal and u should be ok.
Just remember not to lean on the manifold/plenum when working at the donk... :)
Happy Friday, time for third bourbon coke!

Mate, Helicoils are great, while you are at it, block the surface of the manifld where the top section bolts on and same with the top section as they do pull down where they bolt up if over tightened.

Studs are not used in the factory because the studs tend to corrode inside the alloy and when you go to get the top section it can then be jammed up.