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Advice on MGA 3rd gear noise mystery

To: <>
Subject: Advice on MGA 3rd gear noise mystery
From: "SCC" <>
Date: Mon, 4 Jun 2001 11:26:10 -0700
Driving home from a Chicagoland MG club tech session yesterday (thanks,
guys!  very informative), I noticed third gear was making a sound, as

* Frequency of sound is proportional to engine speed while under throttle.
Throttle off, sound diminishes greatly.
* No trace of sound in any other gear (including reverse)
* Sounds like fanblade (metal) contacting rubber or plastic, but it isn't
(fanblade is clear)
* Could also be described as a vibration or warble as if a shaft is
* Similar to a high frequency version of thumping one would hear with warn
suspension bushings, for example.
* Sound is difficult to locate, but is definitely not from the rear of the
car.  Driver or forward.

1962 MGA 1600 Mk. II

I was about to yank the engine and transmission, but then someone who knows
a lot more about MG's than I (which would be most people, actually) said it
could just be a worn universal joint.  I would have thought that would
affect more than just 3rd gear.  But I thought I'd better ask the list (of
experts) for opinions on where to look for the problem before I cover my
garage in my poor LBC's innerds.

The only thing that's been done to the car recently, none of which I can
think would be remotely connected, is Petronix ignition, fan shroud
installation, 165 degree thermostat, and lube for the steering rack.  I
checked all fluids, and everything is in order (no fluid older than, say,
300 miles).  30 weight Castrol GTX in the transmission, 20w50 Castrol GTX in
the engine.  Yesterday was unseasonably cold for Chicago, and the car was
cruising at 160 degrees (lowest it's ever been since I've owned it --
usually hovers at 180), but seemed to be running fine at the lower
temperature in general.

The only other issue the car has (and has had since I got her) is an
occasional backfire when cruising at 60+ mph, and a tendency to stall
occasionally when decelerating from cruising speed under engine braking
until she's really warmed up.

Any help would be GREATLY appreciated!


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