PS Magazine - TB 43-PS-582
PS, The Preventative Maintenance Monthly
ISSUE 582
MAY 2001
MAY 01
PS 582
MAY 01
8
M
ost of you probably figure an exhaust leak at the flex pipes is a fact of life
for M915-M920 and M915A1 trucks.
That's because every truck you've ever worked on has had an exhaust leak
at the flex pipes at one time or another.
But it doesn't have to be that way. The problems are known—and so are
the solutions:
Problem 1
The flex pipes don't fit over or inside the exhaust pipes. They butt up against them,
held in place by couplers. When the flex pipe and exhaust pipe separate, you get
leaks at the couplers. Tightening
the couplers won't help. All that
does is make the leak worse.
Solution
Make sure the exhaust pipe and
flex pipe are in good condition.
Look for cracks, distortion or
burning at the edges. Make sure
the pipes fit against each other
evenly. If there's damage or they
don't fit, replace them. Always
use a new coupler when you put
things back together.
Problem 2
Are you exhausted tryint go keep flex pipes from leaking? You may notice when you
check out the pipes that the diameter of the flex pipe is larger than the diameter of
the exhaust pipe. This messes up the fit between the pipes, and the coupler won't
seal the joint.
Solution
If the flex pipe is too big, you can fabricate a metal shim to use until you get the
right-size pipe.
Make the shim from any
1
∕
16
-in
thick metal that's easily bent. Cut
and form the shim as shown.
Wrap the shim around the end of
the exhaust pipe and butt the flex
pipe up to the shim. Secure the
pipes with new couplers.
Since the couplers are sensitive to
too much tightening, torque them to
45 lb-ft and no more. Eyeball Para
4-35 in TM 9-2320-273-20 for the
full picture.
Cracks, distortions or
signs of burning?
Exhaust Flex Pipes
Living with
M915-Series, M915A1 Trucks.
..
Fabricate
shim using
this design
Diameter
to fit
exhaust
pipe
PS 582
9
1
1
∕
2- in
1
∕
2
1
∕
2
1
∕
2
Are
you
exhausted
trying to keep flex
pipes from leaking?
Exhaust Flex Pipes
Living with
582. 08-09 (C)
4/4/01
10:07 PM
Page 1
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