Exhaust manifold removal pro tips?

YungICY · Dec 30, 2015

Hey guys, I'm doing some exhaust repairs on my 91 Expo which involve removing the y pipe. Things were going way too smoothly for my liking so I went ahead and snapped off one bolt in each of the manifolds. Angelo, does anyone have any pro tips for removing the manifolds? The driver side doesn't look too bad to get to but the passenger side is tight since she's got AC shit tucked in there.

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YungICY · Dec 30, 2015

Possible change of plans. Are those manifolds cast iron?

Also, I should probably mention this is a 4.0 ohv.

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cdxhizors · Dec 31, 2015

I believe they are cast iron. I've heated the bolts and let them cool before and they come out. Any snapped ones I usually weld a large nut to the end of.. The heat from welding it usually frees the stud enough to come out.

enjr44 · Dec 31, 2015

Most folks don't try to fix it by removing the manifolds, you are just going to break more bolts off in the heads. They didn't make them to take apart after a few years.

A lot of folks just drill all the way through the manifold and use a nut and bolt. There is also a clamp type thingy you can buy with mixed reviews (some say they are great, some not so great). Like this http://www.amazon.com/Truck-Broken-Rusted-Exhaust-Diameter/dp/B00E4TMK60

YungICY · Dec 31, 2015

cdxhizors said:
I believe they are cast iron. I've heated the bolts and let them cool before and they come out. Any snapped ones I usually weld a large nut to the end of.. The heat from welding it usually frees the stud enough to come out.

Yeah that's what I changed the game plan to.

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YungICY · Dec 31, 2015

enjr44 said:
Most folks don't try to fix it by removing the manifolds, you are just going to break more bolts off in the heads. They didn't make them to take apart after a few years.

A lot of folks just drill all the way through the manifold and use a nut and bolt. There is also a clamp type thingy you can buy with mixed reviews (some say they are great, some not so great). Like this http://www.amazon.com/Truck-Broken-Rusted-Exhaust-Diameter/dp/B00E4TMK60

Yeah I put a wrench in there and quickly decided they aren't coming off. One I can weld a nut on and probably pull it out but the other side snapped flush with the manifold so I'm thinking about welding a stud onto the manifold.

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alwaysFlOoReD · Dec 31, 2015

On an f150 with the 4.2 I drilled and tapped with helicoil for new studs. Was a pain and had to weld two long bits together to reach the manifold from underneath, but did it.

YungICY · Dec 31, 2015

Tools is where I'm limited. I have all the tools to easily do it on a bench but under the truck I'm gonna have to be a little creative. The one stud has to come out and the easiest route on the other might be the bandaids linked above or maybe just welding a bolt on there.

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alwaysFlOoReD · Dec 31, 2015

You will have problems with welding to cast iron. Brazing will work if the manifolds don't get too hot under engine load, but the metal will have to be CLEAN! I think drilling thru and bolting may be the ticket. And once drilled helicoil isn't much more work. The clamp idea is one I haven't tried but is worth a look.

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YungICY · Dec 31, 2015

I'm gonna have to see if I can finagle my drill up in there. Ideally the best fix would be to run a new bolt and nut on each hole in case it ever has to come off again. Then on the off chance that another bolt snaps it can still be pulled with ease.

Now one last question. In the midst of learning new cuss words, I cut the wires for the o2 sensor. It's a 4 wire, black, grey and two whites. Does anyone know if the white ones have to be wired back the way they were or will they be okay if they're backwards.

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alwaysFlOoReD · Dec 31, 2015

I'm not 100% but I believe the white are grounds. It shouldn't matter.

Exhaust manifold removal pro tips?

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