Re: [ihc] Weird engine problem - calling the experts

[Colin M Rush <salmineo@xxxxxxxx>]

        I too am of the opinion that you may have a vacuum leak
somewhere.  Quick check:  take some starting fluid, and with the engine
running, squirt around the gaskets beneath the carb, under the manifold,
the distributor vacuum cannister, and the vacuum connections.  If the
engine speeds up, when you squirt a certain spot, you have found a leak. 
Slower check and repair:  pull the intake, knock out all of the welch
plugs, remove the EGR, chisel out the coke, and take it to a shop to have
it hot tanked, shotpeened, and magnafluxed.  Either you will find a crack
or your wont.  If it is not cracked, then install new welch plugs (with
just a touch of silicone around the edges before you flatten them out in
the hole), put on a good EGR valve, and then paint and reinstall. 
Chances are that work will fix any leaks you may have had, plus it will
have gotten rid of the rust and coke that were plugging the inside of it,
which should improve engine performance a little too.
        Before you do any of these checks though, disconnect the hose to
the brake booster at the manifold, and the one to the distributor too. 
If either the booster diaphragm or the vacuum advance cannister diaphragm
are bad, they will be bad vacuum leaks.  Be sure to plug or cap the
fittings, and then start and run or drive the vehicle.  If the engine
runs better after they are disconnected, then those are your culprits.

Date: Fri, 7 May 2004 17:16:07 -0700
From: "James Lidberg" <jameslidberg@domain.elided>
Subject: Re:  [ihc] Weird engine problem - calling the experts
No expert here, but ... Sounds like a vacuum leak. Has that been
measured?
 
I did my intake manifold a couple years ago. There are several expansion
plugs on the underside. They can leak.
 
The manifold can be cracked.
 
If the intake is EGR, it is possible to have a vacuum leak from the EGR
valve into the manifold, or way too much EGR 
also.
 
It is important to have the the EGR passage ways clear. I could not chip
out the carbon from the manifold, it was so 
hard I had to have it hot tanked to get it out.

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