Any advice for replacing exhaust manifold gasket in a 454?

[atikovi]

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.

[Bird_Freak]

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]

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]

Great job! I think the composite gaskets would work just fine.

[atikovi]

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]

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]

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]

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]

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]

The best penetrating oil I ever used is a homemade 50/50 transmission fluid and acetone.

[Executive45]

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

[okhmbldr]

Those look like stainless steel headers to me. Blow up the photo. It has several places with welds and the tubing doesn't look cast at all. Spray and soak then give them a twist. And don't try to patch with mixed up junk.

[atikovi]

Gjac wrote:
They are cast iron.

I've never seen cast iron formed into tubular shapes like these, especially with that accordion section in the middle like that.

[opnspaces]

Agreed with daily spraying them for at least a week with a penetrating oil. Even if you are going to have a shop do it you might prevent a few broken bolts and the subsequent increase in labor rate.

[Gjac]

atikovi wrote:

Gjac wrote:
If you look very carefully the stock manifolds are probably cracked anyways.

I thought they were stainless steel?

. They are cast iron. The newer headers may be SS depending on make. Banks is SS. Thorleys carbon steel and ceramic coated.