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How to: Change your exhaust manifold on your 2008-2012 Chevrolet Malibu with the 2.4L Ecotec engine

***Make sure your vehicle is completely cooled off before even beginning to attempt this how-to. Exhaust manifolds get extremely hot and will stay hot for quite some time even after the car has been sitting. Almost best to do this after the car has sat overnight***


Time to complete: 2-3 hours, depending on the difficulty of removing nuts and bolts.

Difficulty: Moderately hard


Tools needed:
5 or 5.5mm socket
6 mm socket
10mm socket
13mm socket
15mm socket
13mm wrench
Short and long socket wrenches
Socket wrench extensions, several different sizes on hand would be good
Torque wrench
Flathead screwdriver
Muscles
Vice grips or an oxygen sensor socket
Penetrating oil for easier removing frozen bolts and nuts

Parts needed:
New exhaust manifold: GM #12643496 or Dorman exhaust manifold kit 674-937.
*GM Exhaust Manifold Gasket: GM #12622668
*GM Converter and pipe seal: GM #24505057

*=Parts you will need if you don't get them in a kit.

Other Part Numbers:
Catalytic Converter Stud - GM #11561403
Mount Brace Nut (secures manifold to catalytic converter) - GM #15032594
Stabilizer Bar Nut (secures manifold to engine) - GM #11516076
Exhaust Manifold Stud (studs in back of engine) - GM #11589054
Upstream Oxygen Sensor - GM #12617648
Downstream Oxygen Sensor - GM #12646200

Let's get started!

1. Make SURE your car has cooled off!

2. Make ABSOLUTELY sure your car has cooled off!!!!

3. I will not stress over numbers 1 and 2 anymore, but heed my final warning, make sure your car has cooled off before starting this project. The manifold can go upwards of 600F.

4. Remove the plastic engine cover for easier access. Once removed, with your 10mm socket, remove the three small bolts holding the heat shield on over the manifold. Remove and set aside.

5. With your vice grips or an oxygen sensor socket, remove the oxygen sensor at the back of the manifold. Place aside or unplug and remove from the vehicle.

6. Now, you will 10 nuts holding the exhaust manifold to the engine, and three holding it onto the catalytic converter. It’s really your choice on where you want to start. I will start on the catalytic converter.

7. You may want to spray the nuts liberally with penetrating oil and allow them to sit for a while, about 30-60 minutes, just to have an easier time to remove them. Do not get overzealous removing these nuts and studs, otherwise you could be in for a world of hurt later on!

8. Take your 15mm socket and at least an 8 inch extension and attach it to your long socket wrench. You’ll want the extra leverage to break these free. Don’t force them too hard though. If you feel it’s going too hard on them, spray them again and wait. You can also use a hammer to lightly tap on the end of your socket extension to help loosen it up. Make sure to remove your socket wrench off of the extension first though.

9. Once you loosen up all three bolts, go ahead and remove the three studs as well. This will make it so you won’t have to lower part of your exhaust system to remove the manifold. Because studs go up from the bottom and front, it’ll be nearly impossible to remove or reinstall without either removing the three studs or dropping the converter. This is where you’ll use your 6mm socket on the end of the studs. Carefully turn them to loosen them up and remove. Set aside.

10. Start working on the engine side. In the diagram below, I have the locations of all the nuts you’ll have to remove. Some are a huge pain in the rear to get to, but I will try and offer advice on some of them. Make sure to continue referencing this diagram as I will refer to the numbers on it. Check below this post to find diagram attached.

11. This is where you’ll use your 13mm socket. The correct way to remove this is from the outside and work your way to the middle. So I’d recommend removing the nuts in this order. 5, 10, 1, 6, 4, 9, 2, 7, 3, 8.

12. If any of the bolts came out with the nut, that’s okay. Spray it down well with penetrating oil and let it sit for a bit, then you can use your vice grips to get a good grip on the bolt and then just wrench off the nut.

13. 7 and 9 are especially complicated to remove, so this is where I’d recommend using your 13mm wrench and feed it between cylinders 1 and 2 and 3 and 4 respectively. I had a very rough time with cylinders 3 and 4’s nut because of the fuel lines being in the vicinity so you can’t really hammer away at it.

14. Once you remove all nuts and set them aside, remove the manifold by sliding it back towards the cabin of the car and remove.

15. Remove the old manifold gasket as well, it should just peel off and out.

16. Now is where the fun begins. You may want to grab a Coke or possible a glass of milk if that’s your sort of thing and have a small break.

17. If any of the engine bolts came out, once you have the nuts off them, just place them back into the hole they came out of and screw them in and once they are no longer able to be moved with your fingers, take your 5 or 5.5mm socket and screw them in tight.

18. Install the new gasket. It’s impossible to screw up as it’ll only go on one way.

19. Don’t forget to remove the donut ring gasket from the catalytic converter. Use a flathead screwdriver to remove. Place new gasket in its spot.

20. Bring in the new manifold and place onto the studs and slide it back onto the engine.

21. Installation is pretty much reverse. As with the tightening process, start from inwards and work your way outwards. So I’d do it in this sequence. 3, 8, 4, 9, 2, 7, 5, 10, 1, 6. Torque specs are 124in-lbs.

22. Reinsert studs to catalytic converter and tighten as far as they’ll go.

23. Reinstall nuts onto studs. Torque specs are 22ft-lbs or 264in-lbs.

24. Check to see if your oxygen sensor is damaged or looks bad. Replace if needed. Otherwise reinstall and tighten somewhat tight.

25. Put the heat shield back on with the 3 bolts.

26. You’re done! Start the car and drive it. Some smoke is normal, so don’t be alarmed

Topic Pinned due to many 7th generation Malibus being a 2.4L and all having this all too common problem.
 

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Thanks for the post. Even though I do not own an ecotec thanks for the post. I am going to start taking pictures the next time I do some front end work because the lack of knowledge on the 7th Gens are astonishing. I may even make a few tuning guides for the different motors and transmissions I just need to work on a few other vehicles first before I get to my cousins ecotec.
 

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Discussion Starter #3
The Ecotec is actually a very easy engine to work on. It's not as big as the high feature 3.6 so there's a bit more room to work with. Properly managed and taken care of, it can have power very similar to the pre-high value engines like the 3100 and 3400 V6s. Since changing my exhaust manifold, I feel as though I have a lot more power and also better fuel economy.

Anyway, you're welcome for the post! I like to be of service wherever I can. I know what it's like not to have a lot of money to spend on car repairs and if I can help others fix their own vehicles and save a bunch in the long run, it's worth it to me. I don't want anything in return, it's just my way of helping pay it forward. I really hope any of my how-to guides can help you out and if you ever run into something that you're able to do and isn't a how-to on here, feel free to post it for others to see and benefit from! I would sort of like this section to be a Wiki of 7th Gen Malibus. :)
 

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Can #16 be substituted with a beer and not a soda or milk?
 
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Discussion Starter #5
Can #16 be substituted with a beer and not a soda or milk?
That's a pretty tough call, but as long as you don't go cross-eyed from too much beer, then I suppose it could be arranged! :D
 

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Can the exhaust manifold affect how the transmission is running?? My daughter bought 2010 Malibu sorry all i Know is it's 4 cyl came with exhaust manifold, the part, she drove to mechanics said it was running really hard like in wrong gear. She went to back it in all of the sudden no reverse. Mechanic says new transmission.
 

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Can the exhaust manifold affect how the transmission is running?? My daughter bought 2010 Malibu sorry all i Know is it's 4 cyl came with exhaust manifold, the part, she drove to mechanics said it was running really hard like in wrong gear. She went to back it in all of the sudden no reverse. Mechanic says new transmission.
No reverse?! Not the exhaust mani. Might even just be low on fluid. I would top it up first, but these cars are known to have tranny issues in some cases. Top off first. Drain and fill if it helped. Worst case, then yes, swap tranny. Never rebuild. Like putting an expensive bandaid on a dam...
 

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How to: Change your exhaust manifold on your 2008-2012 Chevrolet Malibu with the 2.4L Ecotec engine

Make sure your vehicle is completely cooled off before even beginning to attempt this how-to. Exhaust manifolds get extremely hot and will stay hot for quite some time even after the car has been sitting. Almost best to do this after the car has sat overnight


Time to complete: 2-3 hours, depending on the difficulty of removing nuts and bolts.

Difficulty: Moderately hard

Tools needed:

5 or 5.5mm socket
6 mm socket
10mm socket
13mm socket
15mm socket
13mm wrench
Short and long socket wrenches
Socket wrench extensions, several different sizes on hand would be good
Torque wrench
Flathead screwdriver
Muscles
Vice grips or an oxygen sensor socket
Penetrating oil for easier removing frozen bolts and nuts

Parts needed:
New exhaust manifold: GM #12643496 or Dorman exhaust manifold kit 674-937.
*GM Exhaust Manifold Gasket: GM #12622668
*GM Converter and pipe seal: GM #24505057

*=Parts you will need if you don't get them in a kit.

Other Part Numbers:
Catalytic Converter Stud - GM #11561403
Mount Brace Nut (secures manifold to catalytic converter) - GM #15032594
Stabilizer Bar Nut (secures manifold to engine) - GM #11516076
Exhaust Manifold Stud (studs in back of engine) - GM #11589054
Upstream Oxygen Sensor - GM #12617648
Downstream Oxygen Sensor - GM #12646200

Let's get started!

1. Make SURE your car has cooled off!

2. Make ABSOLUTELY sure your car has cooled off!!!!

3. I will not stress over numbers 1 and 2 anymore, but heed my final warning, make sure your car has cooled off before starting this project. The manifold can go upwards of 600F.

4. Remove the plastic engine cover for easier access. Once removed, with your 10mm socket, remove the three small bolts holding the heat shield on over the manifold. Remove and set aside.

5. With your vice grips or an oxygen sensor socket, remove the oxygen sensor at the back of the manifold. Place aside or unplug and remove from the vehicle.

6. Now, you will 10 nuts holding the exhaust manifold to the engine, and three holding it onto the catalytic converter. It’s really your choice on where you want to start. I will start on the catalytic converter.

7. You may want to spray the nuts liberally with penetrating oil and allow them to sit for a while, about 30-60 minutes, just to have an easier time to remove them. Do not get overzealous removing these nuts and studs, otherwise you could be in for a world of hurt later on!

8. Take your 15mm socket and at least an 8 inch extension and attach it to your long socket wrench. You’ll want the extra leverage to break these free. Don’t force them too hard though. If you feel it’s going too hard on them, spray them again and wait. You can also use a hammer to lightly tap on the end of your socket extension to help loosen it up. Make sure to remove your socket wrench off of the extension first though.

9. Once you loosen up all three bolts, go ahead and remove the three studs as well. This will make it so you won’t have to lower part of your exhaust system to remove the manifold. Because studs go up from the bottom and front, it’ll be nearly impossible to remove or reinstall without either removing the three studs or dropping the converter. This is where you’ll use your 6mm socket on the end of the studs. Carefully turn them to loosen them up and remove. Set aside.

10. Start working on the engine side. In the diagram below, I have the locations of all the nuts you’ll have to remove. Some are a huge pain in the rear to get to, but I will try and offer advice on some of them. Make sure to continue referencing this diagram as I will refer to the numbers on it. Check below this post to find diagram attached.

11. This is where you’ll use your 13mm socket. The correct way to remove this is from the outside and work your way to the middle. So I’d recommend removing the nuts in this order. 5, 10, 1, 6, 4, 9, 2, 7, 3, 8.

12. If any of the bolts came out with the nut, that’s okay. Spray it down well with penetrating oil and let it sit for a bit, then you can use your vice grips to get a good grip on the bolt and then just wrench off the nut.

13. 7 and 9 are especially complicated to remove, so this is where I’d recommend using your 13mm wrench and feed it between cylinders 1 and 2 and 3 and 4 respectively. I had a very rough time with cylinders 3 and 4’s nut because of the fuel lines being in the vicinity so you can’t really hammer away at it.

14. Once you remove all nuts and set them aside, remove the manifold by sliding it back towards the cabin of the car and remove.

15. Remove the old manifold gasket as well, it should just peel off and out.

16. Now is where the fun begins. You may want to grab a Coke or possible a glass of milk if that’s your sort of thing and have a small break.

17. If any of the engine bolts came out, once you have the nuts off them, just place them back into the hole they came out of and screw them in and once they are no longer able to be moved with your fingers, take your 5 or 5.5mm socket and screw them in tight.

18. Install the new gasket. It’s impossible to screw up as it’ll only go on one way.

19. Don’t forget to remove the donut ring gasket from the catalytic converter. Use a flathead screwdriver to remove. Place new gasket in its spot.

20. Bring in the new manifold and place onto the studs and slide it back onto the engine.

21. Installation is pretty much reverse. As with the tightening process, start from inwards and work your way outwards. So I’d do it in this sequence. 3, 8, 4, 9, 2, 7, 5, 10, 1, 6. Torque specs are 124in-lbs.

22. Reinsert studs to catalytic converter and tighten as far as they’ll go.

23. Reinstall nuts onto studs. Torque specs are 22ft-lbs or 264in-lbs.

24. Check to see if your oxygen sensor is damaged or looks bad. Replace if needed. Otherwise reinstall and tighten somewhat tight.

25. Put the heat shield back on with the 3 bolts.

26. You’re done! Start the car and drive it. Some smoke is normal, so don’t be alarmed

Topic Pinned due to many 7th generation Malibus being a 2.4L and all having this all too common problem.





My 2008 front catalytic converter is bad. Was there a recall for this? I only have 98,000 miles on the vehicle. I am a college student and I won't be able to replace this. Please help!
 

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2011 Malibu LTZ 3.6L V6 Red Jewel Tintcoat
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The emissions warranty is expired for that 2008. If you want, you can call a local dealer with your VIN to confirm.
 

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I managed to get my old manifold off, the new ring and gasket on, but I can't for the life of me get the new manifold to line up with the bolts. Am I doing something wrong or is there a trick I'm missing?
 

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Manifold bolts onto the engine first, pipe goes on last if I understand you correctly.
 
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