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Rear Exhaust Manifold R&R

FriboRage

FriboRage

New member
So I’m pretty sure I’ve got a cracked rear manifold, and I’m working on a replacement. I’m in the process of a LIM gasket, so I’m thinking about doing it now.

I know a lot of people on here like to drop the subframe a few inches and take it out the bottom, but I’m working in a stall with a pit, and I have nothing to support the motor with, so that’s not an option for me. I’d rather not go that path anyway...

Im wondering how difficult it’ll be to do from the top while I have the blower and rear valve cover off, the dog bones out, and the motor strapped forward.

I’m not that worried about the LIM gasket, it’s just this exhaust manifold I’m stressing over.
 


you dont support the engine at all. just lower the frame some. dont go more then 2-3 inches or you'll tear the steering shaft apart.
 
Just remove the dog bones and the downpipe bolts. Take a ratchet strap and pull the motor forward. You'll have plenty of room then to pull it out the top.
 
Sounds like everyone said it.. with all that stuff out of the way.. should be easy enough. I'd triple check visually looking for carbon tracking. With the downpipe gasket right there.. it's a likely candidate.
 
Alright, got it out and new one in from the top... plenty of space.

On the torque specs, I wanna make sure.

The torque thread here says 22-24ft-lbs, a lot of other sources say like 3 different specs? Like manifold bolt - 22ft-lbs, manifold stud (inner) - 22ft-lbs, then manifold stud (outer) - 89in-lbs?

That’s a big difference, and in my car there’s only 1 nut on the manifold, the right-most fastener is a nut where the stud stays in the head. All the rest of them came out as nuts affixed to a stud.

So what meaning does inner/outer have if the outermost one was a nut? Does that get 22ftlbs or 89inlbs? 89inlbs sounds like really low torque for this..
 
Just make them tight...they're big enough bolts that the 25ft/lbs will be fine. Start in the middle and work your way out then double check the middle when done. When all else fails, use the German torque spec "gutentite."
 


Okay, if 20-something is good enough I’ll do that. On one hand, I’m just scared of snapping one off, but I also don’t want to start it up and hear a tick cause that’s the main reason I’m doing this, it was leaking.

I’ve gotten this far without any major mishaps so I feel like I’m overdue for something lol.
 
Both end ports should have the stud on the outside hole of the port, all the otherss are bolts, or bolts with threaded studs.
 
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Alright rear manifold is in and torqued, working on connecting the egr tube to the new power log. It hasn’t been the easiest fit.

I shaved some stuff down and it fits and ton better than it did in the beginning. There’s still a little bit of a gap, but I’m questioning if it’ll seal or not cause there’s a lip between the tube and flange that looks like it’s own seal.

Imgur: The magic of the Internet

Think that gap will make an exhaust leak? Even with that lip clamped tight between the flanges?
 
it might. supposed to be a gasket in there too iirc.

the tubes are flex able, you can try to manipulate it some to fit more square.
 
So how much cranking should it take if I had everything apart down to replacing the lifters and rear exhaust manifold. Fuel rail drained and everything.

It stumbles like it’s attempting to start but it’s been cranking forever
 


id take the plugs out and crank the hell out of it. like for 15 seconds ten times, then plugs back in and try to fire it up. lifters need to pump up with oil still i bet.
 
Okay, got it started. Running pretty good.

If that egr pipe I linked at the rear manifold were leaking, it would sound like an exhaust leak, right? Like a ticking or roaring...?
 
Well I have an air sucking noise that I swear was coming from back there.

Gunna check it out again tomorrow but I can’t imagine what it would be unless the intake side of the egr valve is cracked, but that’s closer to the top. This definitely sounds like something behind down by the exhaust.

I wiggled around the line going to the map and the brake booster but the sound didn’t change.

LTFT on my aeroforce was -14, but it always ran in the negatives... I think the Overkill tune is just rich... if I had a vac leak loud enough to hear like that, wouldn’t I have positive ltft’s?
 


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