are a number of times when one may wish to remove the muffler from a
Lamborghini. Almost any major engine repair for
example will require the muffler to be removed. Fortunately this is
relatively easy to do in most of the cars. I will illustrate it here
with a Diablo. I will also outline how to go about repairing the
muffler box if one of the catalyst attachment bolts gets broken.
This is common on older (often rusted) cars.
First a few obvious points. Make sure the car
engine is cold. It often helps to put reagents that loosen rusted
nuts on them as few hours beforehand. The nuts used to attach the
catalyst to the muffler box reach high temperatures. They are often
difficult to open in older cars and can snap off (see below).
The muffler box itself is quite heavy. Since you have to bend over
the car to get it out. Watch your back and/or get a friend to help
lift it out.
The whole process is really quite simple. I will
illustrate most of the steps with pictures. First remove the
rear section (and wing) of the car. This exposes the silver heat
shield that covers the hot muffler box (fig 2). Next get under
the car and open the two bolts on the two C-clamps that attach the
catalysts to the engine (fig 3). Remove the 3 nuts on the
bolts that attach each catalyst to the muffler box (fig 4). Take care with
these nuts they can break easily. Figure 5 shows the two
catalyst units removed. Note you can actually get the muffler box
out without removing these two catalysts. However the whole unit is
quite heavy and difficult to get out. Next remove the two
nuts on the side of the muffler box that attaches it to the frame of
the car (fig 6). Next remove the rear mounts of the muffler box.
There is no need to open the large bolt containing the spring.
Just open the 4 attachment screws as shown in figure 7. Finally
remove the two c-clamps under the muffler box that hold the tail
pipe in place (fig 8). Then lift the muffler box out of the
car taking care not to scratch anything. Figures 9 - 11 show
the removed muffler box, catalysts and tail pipe.
While you have the tailpipe out, you may wish to
spray it with (black) high temperature paint as shown in figure 11.
You might also wish to brush the rust off the various c-clamps and
spray them as well. This prevents them form rusting in the future.
What if you shear off a nut.
- Even with the best care one can shear off a muffler box bolt when
they are old or rusted. This happened to one of mine as shown
in figure 12. Fortunately this is easy to repair. First cut
the broken bolt down to the surface of the box (fig 13). Then drill
out the old nut as shown in fig 14. Use a drill bit one size smaller
than the bolt. Then with a treading die (available in most
hardware stores) re-do the treads as shown in figure 15.
Remember Lamborghini cars use metric measurements. You need a 8 mm
tread in this case. Figure 16 shows the new treaded box.
Screw in a new bolt with a nut attached as sown in fig 17. Then cut
the extra treads above the nut as shown in figure 18. Then
screw off the nut. (You attach the nut first so you reform the
start of the tread as you screw the nut off).
- Reattaching the muffler
- Reattaching the muffler is simply a reversal of all of the above. Place the
muffler box back into the car. Start first by attaching the two
catalyst units through the c-clamps to the engine. Then attach the
catalyst units (3 nuts each) to the muffler box. Them tighten down
the two side nuts that hold it to the frame of the car.
There is one trick in attaching the rear muffler box spring mounts.
Use a "Vice grips" to press the attachment bracket to the frame of
the car so you can then screw in the 4 small nuts (fig 7).
It is important to start with the c-clamps at the engine, then
catalyst then box mounts. If you d it in any other order things may
not line up properly. It is difficult for one person to attach the
tailpipe by holding it in place and at the same time attaching the
c-clamps. A trick I found helpful is to string the tailpipe up with
a cord as shown in figure 21 and then maneuver it into position with
Start the engine up in a well, ventilated area and check all joints
are tight. If there is a leak, you will hear it or feel the
exhaust blowing against the back surface of your hand. Try
tightening nuts further and/or open a joint and put one of the many
muffler sealing pasts on a joint. If you are careful you
should not have broken the gasket that seals the catalyst units to
the muffler box. If you did pick two up at any muffler bringing
yours with you. Replace the heat shield and rear section of
the car and you are done.