New to the forum. Have exhaust manifold question

[fidget071577]

Does anyone know if there is a specific tightening sequence for the exhaust manifold for a 2018 model Mirage G4 and if there is what the tightening sequence is?

[7milesout]

Fidget - Until someone comes with an actual sequence spec'd by the factory (engineers), I will tell you the sequence I would use, not having access to factory info. My background is in automotive engineering, and I have worked on these specific kind of issues in automotive and my current engineering segment.

I would work from inside out. Meaning, start on the center exhaust port. I don't know, but I'm assuming there are 2 fasteners per port. On on the left or left-ish, and one on the right or right-ish of each port.

From looking at the exhaust manifold, let's number the fasteners from left (passenger) to right (driver) side. 1, 2, 3, 4, 5, and 6.

The tightening sequence would be something like this: 3, 5, 2, 4, 6, and 1. Do that to finger tight. Repeat the pattern to about half-torque spec. Then repeat it again to torque spec.

All this may vary if the number of fasteners are other than 6. In any event, do it in a similar way as I mentioned (from inside to outer) and I think you'll be fine.

[fidget071577]

Fidget - Until someone comes with an actual sequence spec'd by the factory (engineers), I will tell you the sequence I would use, not having access to factory info. My background is in automotive engineering, and I have worked on these specific kind of issues in automotive and my current engineering segment.

I would work from inside out. Meaning, start on the center exhaust port. I don't know, but I'm assuming there are 2 fasteners per port. On on the left or left-ish, and one on the right or right-ish of each port.

From looking at the exhaust manifold, let's number the fasteners from left (passenger) to right (driver) side. 1, 2, 3, 4, 5, and 6.

The tightening sequence would be something like this: 3, 5, 2, 4, 6, and 1. Do that to finger tight. Repeat the pattern to about half-torque spec. Then repeat it again to torque spec.

All this may vary if the number of fasteners are other than 6. In any event, do it in a similar way as I mentioned (from inside to outer) and I think you'll be fine.

I actually tried this because I have been a mechanic for 20 years, it still leaked. I ended up actually somewhat mimicking the sequence for the Lancer EVO. There are only 3 bolts and 2 nuts. The sequence that I used was 5,1,4,2,3 using the same numbering that you used in your example. It no longer leaks. The sequence would be in simpler terms drivers side bolt, passenger side bolt, drivers side nut, passenger side nut, center bolt. Kinda backwards from everything 20 years experience has taught me but if it works it works

[7milesout]

I actually tried this because I have been a mechanic for 20 years, it still leaked. I ended up actually somewhat mimicking the sequence for the Lancer EVO. There are only 3 bolts and 2 nuts. The sequence that I used was 5,1,4,2,3 using the same numbering that you used in your example. It no longer leaks. The sequence would be in simpler terms drivers side bolt, passenger side bolt, drivers side nut, passenger side nut, center bolt. Kinda backwards from everything 20 years experience has taught me but if it works it works

I agree. The concern I would have with that is I think it may *tend* to build stresses in the more center sections of the exhaust manifold. But, it could also NOT build up stresses depending the quality of the exhaust manifold. In any event, not leaking is more important anyway. So, I'm in agreement with what you did.

[fidget071577]

For anyone else who may run into this issue I would highly recommend that you change the exhaust pipe flange gasket (that's the one with the springs on the bolts) at the same time. I tried to reuse the flange gasket and now have to get back under the car to change it because the exhaust is now leaking from the flange gasket

[7milesout]

Cani Lupine had an exhaust leak at his manifold and it was throwing a P2096 code (if I remember). Has a good thread going about it.

[Basic]

Can I ask what happened to cause the manifold to need to be off?

[fidget071577]

Can I ask what happened to cause the manifold to need to be off?

My manifold gasket was still the one that came on the car from the factory and it started leaking. When I removed the old gasket it was torched and definitely needed replaced.

[Fummins]

Fun. I’ve been putting off replacing the manifold(front cat) on a 2017 with 248k miles. I like to do things twice so I’ll reuse the old gasket if it doesn’t tear apart

[fidget071577]

Can I ask what happened to cause the manifold to need to be off?

Fun. I’ve been putting off replacing the manifold(front cat) on a 2017 with 248k miles. I like to do things twice so I’ll reuse the old gasket if it doesn’t tear apart

It shouldn't tear apart because it is a metal gasket but mine was burnt in several places and somewhat warped so I had to replace it. Just make sure that it isn't torched and you should be fine