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MG MGB Technical - New noises

This may be too general for anyone to venture an answer but I thought I'd try. I have 1980 B roadster (non OD). I pulled in the garage last night and, once at idle, noticed a pronounced noise I can only describe as a continuous "thwack...thwack....thwack" coming from the bottom end. Upon inspection it sounded more like it was behind the bottom end in the tranny. The noise is independant of engine speed with clutch all the way out (neutral). It goes away when I depress the clutch. Anyone willing to offer a guess as to what the cause might be. Thanks.
Brian

Brian,

not much to go on so i'll take a stab in the dark. first motion or input shaft has worn a needle bearing or you've chipped a tooth on it. when you depress the clutch, first motion stops moving i believe so maybe thats why the noise goes away?

i hope i'm wrong cause it would be big bucks and time to fix.

what happens when you put it in gear and go?
how many miles on the engine and gearbox?
this sounds like one for click and clack!!

good luck--Paul
Paul Hanley

Hard to tell without actually hearing the noise.

Jack up the car to give the undercarriage a
pre-flight inspection. Grab a handful of wrenches
and check for loose bolts.

Try looking for parts that might be able to tap into
each other, or rattle, from engine idle shake. ie:

- exhaust system-to-chassis or crossmembers;

- brake cable-to-chassis (especially at the
hold-down loop near the battery box frame;

- loosely hanging speedo cable (sometimes the
cable will rap against the inside of the tranny
tunnel, and just needs to be moved aside)

- loose parts (or road debris) at the clutch linkage
(grab the clutch throwout fork and check it for
excess looseness or play)

- loose shock link

- loose shifter (plastic shifter bushing missing?)

- loose fuel pump bracket

- check the engine and transmission mounts
(sometimes, the rubber blocks can separate from
the metal pads)

You get the idea.
Daniel Wong

This thread was discussed between 29/08/2003 and 30/08/2003

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.