exhaust manifold leak

What engine

His '95 Pace has a Ford 460 V8...

No, it has to be removed.

If Dutch is right about 460, Scott is 95% right that head has to come off. Common 460 problem. We had an 84 Class C with a 460 and warped manifolds. I was able to get every bolt out, but those were all intact bolts that I could bang on till the rust grip was released a little. A friend's 460 in a 93 Class C had broken bolts. Spent days, trying to remove, finally pulled the head. An automotive machine shop with a "belt sander" can re-surface heads and get them flat. A cylinder head machine can't do it.

With more than your low miles, I'd be justified in a Valve Job. Pull Heads, Recondition, New Guide Seals, etc. etc. A machine shop can get those stubs out. They'll be thankful you brought it to them before you broke a stud remover off in one, a drill bit in another, and so on.

You live in (well, near to... I've been to Culpeper...) a very populous area. There are professionals who go around removing broken fasteners. They use a metal disintegration device. Sounds like a Star Trek Disruptor Beam, and it's probably related to the plasma cutter bank robbers use in movies, but it vaporizes the fastener in place. You can drive the coach, so you might be able to get it to a shop that's equipped for the job. Call some hot rod or restoration shops. White Post (in White Post!) is an hour away. Another I know is Black Wolf in Woodbridge a little over an hour. I'm sure there are more, and you can also call machine shops and ask if they know of a service to help you.

Every once in awhile, somebody gets'er done at home. Goes in there, manifolds off, no more bolts broken, stubs out, done. Probably with new or re-surfaced manifolds, but done. The majority end up with something they can't drive. Classic Dirty Harry: "Do I feel lucky?"

If you have a 460 and the right side manifold is leaking, then it's an easy project. Jack up the coach and insert jack stands. From underneath remove the two bolts or nuts that hold the "Y" pipe to the manifold. With the coach jacked up, there is plenty of room to reach over the top of the tire and remove the manifold bolts. As previously mentioned, wack the heads of all the manifold bolts to shake the rust loose. Hit them really hard, you won't break any thing. No need to spray any thing out of a can. Take the necessary action to remove broken bolt. DO NOT use over the counter replacement bolts. Go to Ford for the replacement bolt, as it was designed for hot manifold service. Yes it will be pricey!
Take the manifold to an automotive machine shop and have it resurface, before installing. They can resurface the manifold by running it over a head resurfacing stone. Clean the head ports with a wet stone and mineral spirits. No gaskets used or needed.


Richard

I just did both of ours on our 460, the only thing i had to heat up to get off was the manifold to the cross-over pipe, everything else came off easy considering its a 1977. and did not need to jack it up at all, was enough room to slide under to remove the nuts for the cross over pipe. Ours also did have a gasket in there as well, and just dressed up the manifold face with the belt sander
view on right side without the dog house, the two front bolts you can get from under the hood, the other 6 from inside

On ours, a Class C, remember, the driver side rear bolts were still there, but the manifold was visibly warped away from the head, and the OEM gasket was burned through. I sprayed the bolts daily for over a week. When I went to remove them, I had a very solid S-K ratchet and the socket fit well. A little tweaking and rocking back and forth (loosen to tight and tight to loose) then they came out. I sprayed lubricant on the bolts and kept working them so they didn't seize. Manifold required a re-surface to get the port flanges clean AND true to each other and the head surfaces.
The remark about no need to spray the bolts is correct. When I got the bolts out on driver side, there was absolutely NO sign that the penetrant actually entered the thread area.
When I looked at the passenger side a couple years later, I saw that the 9/16" bolt heads were wasting down to a smaller size. Also noticed I could poke a long extension through the space where fender liner met frame. I put a 13MM socket on the extension, started it onto a head, and drove it on by hammering the extension. The bolts didn't just come out, they came out easily. That made me a fan of hammering. There's so much iron around those bolts, I doubt a homeowner torch will help.
This case is a Class A and I've never seen that engine access. The case is also broken bolts, much harder to access. We don't know if the coach has a lot of rust/corrosion. That's why I'm voicing caution.
There are tools to help with extraction, basically drill guides that get mounted over a broken bolt, held in place by a bolt in a usable hole. Guides help prevent drilling crooked and getting into the threads. Bad drilling is one problem. Breaking a drill, extractor, or tap in there is the other.

Use this with clean threads and fasteners and a simple ratchet and socket can remove exhaust bolts thirty years after being heated repeatedly to cherry red hot. A friend spent three days applying this stuff to every nut and bolt in his exhaust system in a 454 engine.

It isn't a gimmick it works. And nickel is far better than aluminum or copper anti sieze when high heat is involved.

i have in the past on other manifold jobs, when the bolts are really questionable, is to just take the cutting torch and blow the heads off, remove the manifold, then i can get into heat the stud that's left, and they remove easy, a lot easier than trying to get a broken bolt out of the head. had a dodge diesel years ago, i spent hours getting the first side off, what was 14mm heads, where now 12mm, between the spray and was a real pain, the second side i figured i would try something different, and just blew all the heads off, took less than and hour and the manifold was off and all the old bolts came out with heat and vise grips...