ROAD AND WORKSHOP by HANDYMAN
Page 55
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The G.V.9 Faulty Exhaust Systems
WHILST in no way directly contribu
ting to an unsafe vehicle, other than as a fire risk, a faulty silencer or piping will readily: attract.the attention of a vehicle examiner and whether suffering from loose joints, broken flex, split silencer body, or ragged tail pipe, he can quite rightly add this to his list of defects as an item indicating neglect and requiringattention.
Nearly all road vehicle exhaust systems give a good first life, and only after part repairs are Made at some future failure does the system then begin to he troublesome. A common mistake on the part of the repairer is a too-ready use of flexible exhaust piping.. Often this is fitted between engine and silencer, in quite long lengths; to replace normal exhaust tubing simply because it offers a fast and easy repair. Yet all too Often this form' :ff repair is short lived, unless a little thought is given.
In a few weeks only, much of this so-called flex pipe becomes solid and immovable, and where the silencer is firmly secured to the chassis and the engine free to swing, the flex pipe is quickly broken. Quite often also. stays or brackets that are designed to permit some radial freedom • to a silencer are unwittingly bolted solid, the swing and kick of • a diesel speedily fracturing the piping between.
Front-mounted silencers can be troublesome because of this, repeatedly failing. and on one engine with a fair amount of
oscillation, the only cure has been to drop brackets from the-engine 'itself to carry the silencer. In the main; however. the 'manufacturer makes fair 'provision for .engine movement, and when .repairing. it is wise to stickCo his approach to the problem.
Quite often, in fitting flex pipe to a silencer stub or fall pipe, the welding torch is used with too good effect. The thin walled flex is "killed ", or its packing destroyed, and in no time at all is broken and. loose. There is also a risk in welding close to the end of a straightthroughsilencer, in that the slag or glass wool packing will tire, and this can burn away almost 'unnoticed--that is, until the engine is started and the silencer as such is then found to be useless.
'Pipes leaking between manifold and silencer are dangerous as well as disturbing. and in certain instances have been known to cause overheating and damage, and even a vehicle fire. From the noise angle, the M.o.T. examiner will be much more inclined to have a closer look at the vehicle approaching with a roar than at the one which approaches with the subdued note of a tight and cared for exhaust system.