240 engine area rattle finally fixed

When I bought the 240 it had a 2000-2100 RPM rattle. I mentioned it
here about two years ago and a solution was mentioned, but i never got
around to it, just living with it. I finally had a few spare moments
and remembered about the rattle (sort of like the old joke about the
roof don't leak when it isn't raining). Sure enough, the suggestions
were right.

the rattle is from the header pipe between the manifold and the
resonator(?) in front of the catalytic converter. That pipe is double
walled, but there is nothing between the two layers of pipe. As years
go by, the heat/cooling cycles causes the inner and outer pipe to
separate just a bit, and they get harmonic vibrations in certain RPM
ranges. My solution was to use self-tapping sheet metal screws. I used
4- two in each pipe- one about 8" from the manifold and one about 8"
from the resonator. I ran the full screw all the way in to cut the
threads, then cut four off real short so they would protrude as little
as possible into the exhaust flow.

That did it! Took it for a test ride this AM, and what a relief! it's
like driving a different car!

If I had a spot welder I would have just drilled a small hole and
stick welded them together.

 

My mom's 245 did the same thing and I used the same solution. Every once in
a while the screws would still manage to loosen up and it would rattle again
so eventually I just cut off the heat shield. That was about 4 years ago
with no ill effect, time will tell I suppose. That car was my introduction
to Volvos, bought new in '86 she's still driving it, 275K and the motor has
never been opened and runs great, despite years of neglect and abuse before
I was old enough to know how to work on it. If they made a 240 body out of
stainless the car would last 100 years.

 

An even better solution would be to drill the appropriate sized
holes, then use screws that are just long enough to reach the inner pipe
- and file their ends flat. I think that eventually you will have an
exhaust leak there...

 

no kidding? acura integras had a similar problem a few years back.
sheesh.

 

This is the perfect solution! I also had a rattle from a loose shield located right after (toward the back) of the one I fixed. Did the same thing with the self tapping screws.
So nice to hear my quite car again!!! Thanks Randy!!!!