On my 1988 Southwind the driver side is leaking and wont pass inspection. I have a 1989 P30 factory service manual but it pretty much just says to remove spark plugs, remove exhaust pipe, remove manifold bolts and plug shields, remove manifold. I'm sure it's more involved than that.

Given the age of your vehicle, every nut, bolt and screw will be rusted tight. Get lots of penetrating oil, a top quality set of drill bits, and stud and bolt extractors. You will undoubtedly run into broken bolts and fasteners when you try to loosen them. Also get a good supply of top grade nuts, bolts, and studs for replacement.

Bandaides. Plenty of bandaides for the knuckle-buster bolts.

Should it be hot or cold when removing the bolts?

The best advice I can give you is don't just replace the gasket, replace the exhaust manifolds with headers. If you look very carefully the stock manifolds are probably cracked anyways. The old 454's and 460's run hot anyways and tend to crack and burn spark plug wires also. I would also replace the ign wires with Hi temp 10.4 MM wires like the Taylor Extreme wires while you are at it. Your engine will run a lot cooler and the fan clutch will come on lest often, not to mention increasing your HP between 60 and 80 HP. If you plan to do the job yourself soak the bolts every day for a week with Kroil oil and tap each bolt head each day to set up a capillary action to get the oil into the threads. If the bolts won't come out or break off, I would let a garage do it.

Get a hold of Ivan at Pine Hollow Automotive in PA !(P.S. I agree, the manifolds are likely cracked.)

Any advice for replacing exhaust manifold gasket in a 454?

Bird_Freak
Explorer II
May 16, 2020
After restoring old cars for 35 years the best penetrating spray I found is Kroil.
Several shady folks here I would never buy anything from. I just hope they get treated the same on their next purchase.
atikovi
Explorer
May 16, 2020
Turns out those are the wrong gaskets. This manifold has round ports and those gaskets are oval. Looks like I need a Fel Pro 1412 or Mahle 95100SG. Any idea what heat riser gasket it would take? The distance between bolts is 3 9/32" and the hole diameter is 2 9/16" but I came up empty.
okhmbldr
Explorer
May 16, 2020
Great job! I think the composite gaskets would work just fine.
atikovi
Explorer
May 15, 2020
Got it off today in less than an hour.

Didn't bother using any fluid as it's mounted with bolts and no way to reach the threads behind the manifold. Bolts came out without any issue. Which gasket should I use? This metal GM gasket for about $20?

Or these composite style aftermarket for half that for a pair?
Executive45
Explorer III
May 15, 2020
atikovi wrote:
Brian in Michigan wrote:
Are you sure its a blown gasket and not a cracked manifold?

At this point does it matter? Either way it has to come off.

Well, yes, it does matter. If the manifold is cracked, replacing the gasket won't fix your problem. :h
Krusty
Nomad II
May 14, 2020
I would definitely be tempted to go over it with a stethoscope and figure exactly where the noise is coming from before I took it apart.
atikovi
Explorer
May 14, 2020
Brian in Michigan wrote:
Are you sure its a blown gasket and not a cracked manifold?

At this point does it matter? Either way it has to come off.
BrianinMichigan
Explorer
May 14, 2020
I changed mine over to headers about 10 years ago. Used my acetylene torches and got each bolt red hot then let it cool for a minute. Each bolt came right out. Are you sure its a blown gasket and not a cracked manifold?
mike_brez
Explorer
May 14, 2020
The best penetrating oil I ever used is a homemade 50/50 transmission fluid and acetone.
Executive45
Explorer III
May 14, 2020
K Charles wrote:
atikovi wrote:
K Charles wrote:
your selling it. Get it hot, mix up some furnace cement, or buy some pre mixed, and but it on the leak. Let it dry before starting.

For a blown gasket?

It will stop the leak.

IMHO, Do it RIGHT or Don't do it at all. Passing along a known problem to an unsuspecting buyer is wrong on many levels. Also, given the age of the coach, whoever buys it will most likely be someone who can least afford to fix it. If you do band aid it, morally you should let that be known to the buyer.

As to changing out the gasket, yes, it's that easy. Spraying PB Blaster or penetrating oil every day for a week is solid advice. I'd spray, wait a day and try to remove them. If they don't budge, repeat. Cold or hot won't matter except for you comfort level. I'd work on it cold. You might get lucky and the bolts will spin right out. Go slow and don't try to force them or they may break. After spraying a quick rap with a hammer may help in working the penetrating oil into the bolt threads....good luck....Dennis