Any tips for changing the right side exhaust manifold on an LT1?

I have an exhaust leak from somewhere near the outlet flange. The studs are nearly rotted away underneath and the flange itself is heavily corroded to the point where I don't think new studs are an option -- not enough of the flange casting left, what's there will just snap off when torque is applied. So a new manifold is on order.

While I'm sure it will be awkward, hopefully I can get the manifold bolts out of the head. (I changed the gasket on the other side a year ago, and they all wound out). Looks like maybe the alternator has to come out.

The real joker in the deck looks to be the EGR tube. Darn near impossible to remove from what I can see. Searching for an answer, I found a post on the Impala SS forum that suggests removing the tube at the intake manifold end and leaving it attached to the exhaust manifold while lifting that out. Will that work on a Roadmaster? Another suggests bending the tranny dipstick tube to the firewall and removing the bolt retaining the tube to the manifold instead.

Any insights or other tips?

No need to replace the manifold unless it's cracked. The cat to manifold nuts will come off with heat. Even if you snap them off, you can put new studs in the manifold. The bolts to the head: air impact them all. From up top, down below, through the wheel wheel, the gap between the inner fender and the frame. With a bunch of extensions and wobblers. If they break, they would have broken anyways. The good ones will spin right out. If one breaks, you can look at it on the break, it won't be shiny on the break if it was already snapped. EGR: get the cat out, you'll have space to get up there and get the bolt.

jayoldschool wrote:

The cat to manifold nuts will come off with heat.  Even if you snap them off, you can put new studs in the manifold.  

The nuts are little round blobs of rust surrounding the needles that remain of the studs. The manifold has to come out to drill out those studs, assuming the whisker thin remains of the cast iron flange surrounding the studs doesn't snap off in the process. For $100 I can buy a brand new manifold complete with all the studs, nuts and gaskets shipped to my door from Rock Auto, so it's just not worth my time to try and save the old one.

I'll try dropping the cat to access the EGR tube. Do you know if the alternator or anything else has to come out before removing the manifold?

If the manifold is not leaking or cracked, and there are no missing bolts, I wouldn't remove it. The studs screw in. I live in the same weather as you, I know what those blobs of nuts will look like. They will come off with a torch and an impact. Drop the starter for easy access on the inside one. Then, just change out the studs. With the torch help. Don't be afraid to take this one to a shop, exhaust guys do this stuff all day long.

If you're determined to do the complete manifold: take off the alternator, too.

I threaded the driver's side cat and manifold out through the bottom of the car.  I think you can do the same with the passenger side, but remove the spark plugs and be careful of the coolant temp sensor in the passenger side head when you do the passenger side.  Yes to the alternator coming out if you remove the manifold.

And so far I've been able to blast out all of the manifold bolts through the wheel well gap with an impact gun.

I've tried drilling out broken studs and I have no talent for keeping the drill centered. So I'm using a welder to weld nuts onto the studs and then back them out that way. The welding action also zaps and vaporizes any corrosion in the threads and helps loosen the stubs as well.

UPDATE:

I finally found some time to get back to this, hoping you guys were right and I could just change the studs. But trying to get access to the bolts through the wheelwell, I found it's not the gasketed joint that's leaking -- there's a hole corroded right through the side of the manifold just above the joint. So the manifold will definitely have to be changed. Yuck.

It's times like this that I wish I had a nice warm, dry shop to work in. This may just have to wait until spring now.

Update on this - you *might* be able to thread the passenger side manifold and cat out the bottom together if you've got the car at least three feet off the ground. Otherwise you'll have separate them. Given age and corrosion, most will break. Take them to a muffler shop or welding shop and heat will get them out. Dorman 03133 has 6 new studs and nuts specifically for this, and most parts stores stock them.