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During
a routine maintenance inspection, I noticed that the exhaust bellows on
my 3.0L four-cylinder stern drive felt hard to the touch and showed some
signs of wear. How difficult is it to install a new one? G.R.,
via e-mail
Not
very. I’ve supplied you with two diagrams to help you out. Even
if you decide to hire a mechanic, the descriptions that follow will help
you know what to expect. The top diagram is an exploded view of the manifold
and exhaust system, and the other is the bellows area itself.
The
first step is to loosen the upper clamps that attach the bellows to the
exhaust elbow as shown in the bottom figure. Grab the bellows on top and
move it back and forth, twisting it if necessary in preparation for removal.
Using the same diagram for reference, remove the fasteners attaching the
exhaust elbow to the manifold, and lift the elbow from the manifold and
studs. For good preventive maintenance, you should also replace the gaskets
and restrictor plate. While they might look okay, it’s not worth
taking the chance. (Have the new ones ready when you begin reassembly.)
Loosen
the lower clamps, and remove the bellows from the exhaust collector. You
should be able to free the bellows from the elbow without too much trouble.
If you encounter resistance, carefully use a flat-head screwdriver to
pry it free.
Next
check the exhaust flapper valve. Refer to the top figure for its location.
If it is stuck or damaged or has been improperly installed, you must replace
it. A faulty one can restrict exhaust flow, allowing water to back up
into the system and perhaps even into the engine.
Now
drive the pivot shaft (see top diagram) from the valve and bushings using
a small-diameter punch. Push the rubber bushings, from the exhaust pipe,
being careful not to drop them into the pipe. Apply Scotch Grip rubber
adhesive to the new bushings, and insert them into the bores of the exhaust
pipe. The flanged side of the bushings must face towards the inside of
the pipe.
Position
the new exhaust flapper valve in the pipe, with the long side of the valve
facing down. Insert the pin through one rubber bushing and valve flange,
and align the pin with the second bushing. Once you’ve done this,
push the pin through to the second rubber bushing. Test the valve to ensure
free movement. The pin ends should be flush with the exhaust pipe on both
sides.
You
are now ready to install the new bellows. To make it easier to place them
onto the exhaust pipe and elbow, lubricate the insides of the bellows
with soapy water and place it and the clamps on the exhaust collector.
Position the end of the bellows with one rib (the short end) downward
on the exhaust collector pipe. The end of the bellows with two ribs (the
long end) must be positioned toward the top.
Place
two clamps around the top of the bellows without tightening them, as they
must be loose to permit installation of the exhaust elbow. Coat both sides
of the new gaskets with sealer, and then position both gaskets and the
restrictor plate on the studs of the manifold.
Install
the exhaust elbow, and torque down the fasteners according to your engine
manufacturer’s recommendation. It should be around 12 to 14 ft./lb.,
but make sure you check. Take care that the bellows is on straight and
not twisted, then tighten the clamp screws. Start your engine, look for
leaks, and make sure the operating temperature is within acceptable limits.
While
most bellows last two years before showing signs of wear and tear, it’s
best to inspect them every few months.
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