Sounds of the MG: Zizzes, Clunks, Rattles & Ticks

October 6, 2022 | John Twist | Noises, Test Drive

By John Twist

The familiar sounds of the MG — a throaty exhaust, the whine of the engine, the sounds of rushing air — make MG driving its best! Strange and unusual noises may be simply annoying, but they also might be warnings signs of impending failures. A thorough test drive will elicit any unusual noises – now all you have to do is translate!

Find a quiet street or country lane. Sitting still, clutch released, rev the engine from idle to 4500 rpms and then back down to idle. Drive in all four gears, throughout the rpm range. Try maximum accelerations, decelerations, and stops. Coast with the engine off (don’t lock that column!!). At 30 mph in second gear, rapidly knock the throttle to the floor and release, repetitively, causing the MG to jerk fore and aft, forcefully. At 60 mph listen as you accelerate decelerate and continue at “no load.” Turn tight corners. This is a TEST DRIVE – so TEST the MGB to the limit of its mechanical condition and your ability to drive.

GEARBOX NOISES

“SWISHING” from the gear lever, noticeable at idle is a normal sound, but it is offensive. Repair this by fitting an original gearknob; by pushing silicone gasket goo into the knob before screwing it onto the gear lever; or working with the gear lever.

“SCREETCH” when depressing the clutch, engine cold, is caused by a damaged pilot or spigot bushing. This is not damaging, but offensive. Repair this by removing the engine and/or gearbox to replace the spigot bush.

“TICK – TICK – TICK” in reverse is caused by chipped teeth on the reverse gear or laygear. This is very expensive to repair, as the gearbox must be removed from the car!

DASHBOARD NOISES

“BUZZES” are caused by loose expanses of metal or loose lines. These are often very difficult to find! Repair these by locating the offending sheet metal or metal line which is vibrating.

“CLICK” from the glovebox after the engine is shut off – the proper operation of the anti run-on valve.

“SQUEAK” from the steering wheel when turning – the column covers are fouling the wheel, especially 1977-80.

REAR END NOISES

“CLUNK” at any speed, when travelling over bumps is caused by loose or faulty rear shocks. Repair this by simply tightening the shocks to the frame member.

“CLUNK” at any speed, between acceleration and deceleration is cause by worn wire wheels or hubs. Diagnose this by jacking up the rear axle, having your associate depress the brake pedal, then examining the rotation of the rear wheels. If the splines are perfect, then the rear wheels will not rotate. Severely worn hubs and splines will evidence themselves by up to a two-inch rotational freeplay!

“CLUNK” at any speed, between acceleration and deceleration is caused by worn or missing differential and pinion shims (see “Eliminating Rear Axle Clunk”).

“CLUCK” when travelling over a bump is caused by a loose shock link at the rear leaf spring. Repair this by replacing the shock link (requires removing the rear shock and bottom axle plate as an assembly).

“WOW WOW WOW” at higher speeds, either during acceleration, deceleration or free float is caused by faulty backlash or a loose pinion in the differential assembly. Repair this by tightening the nut on the pinion – or by replacing the differential.

“CLACK” between acceleration and deceleration, 1977 MGB and newer is cause by a loose rear anti-sway bar. Repair this by tightening the bolts on either side of the sway bar to body.

“TICKING” rapid ticking, right side – Fuel pump. Perforated fuel lines – or you are simply “out of gas!” The factory pump is very quiet. Some aftermarket pumps rattle incessantly!

“CLUNK” often accompanied with a ring, between acceleration and deceleration is caused by a faulty U Joint. Repair this by removing the drive shaft and changing the U joint (see “The Fastest U Joint in the World”).

FRONT END NOISES

“CLUNK” at the end of braking is caused by worn washers or a worn distance tube on the bottom of the kingpin. Repair this by replacing the bottom distance tube and washers (and sometime the bolt).

“WHISTLE” at high speeds for the 1980 MGB is caused by the reliefs in the headlamp trim ring. If this truly drives you nuts, change the headlamp rings to the earlier model.

“SQUEAL” upon braking is caused by glazed brake rotors. Repair this by “deglazing” the rotors.

CORNER NOISES

“THUMPING VIBRATION” is caused by a faulty shock or a grossly out-of-balance wheel. Repair this by replacing the shock or balancing the wheel.

“WOP WOP WOP” can be caused by a flat tire, or flat spot on the tire. Inspect further by jacking up each corner, then spinning the tire while feeling the tread. Flat spots are easily recognizable.

“CLICKITY CLICKITY” from the RO-style wheels at slow speeds is cause by loose hubcaps. Repair this by spreading the “fingers” on the hubcap and refitting it.

ENGINE NOISES

“ZIZZES” at higher rpm at rest or at speed, dual carburettor MGB is caused by a cracked heatshield. Repair this by removing the carbs and either welding or replacing the heatshield.

“TICK” at idle which follows engine rpm but disappears above idle is cause by piston slap (worn pistons or bores). Repair this by honing/boring the engine and fitting new rings/pistons.

“TICK” throughout the rpm range, at rest or at speed is cause by excessive valve lash or by worn cam follows or camshaft. Further diagnose this problem by removing the valve cover and starting up the engine. Then place a 0.010” feeler between each rocker and valve stem – the ticky noise will cease when the feeler is inserted.

“RATTLE” upon acceleration is caused by over-advanced timing or faulty rod bearings (oil pressure below 50 psi at speed, accompanied by this rattle during acceleration, is a good indicator of faulty rod bearings). Repair by retarding the timing or by changing the crank and rod bearings.

“RATTLE” upon deceleration only is caused by worn or loose gudgeon pins (wrist pins on the pistons). Repair this by fitting new pistons.

“SCREAM” (like a stuck pig) in model year 1977 or later is caused by a frozen bearing in one of the cooling fans. Repair this by opening and oiling the faulty bearing – or by replacing the fan motor.

“SCREAM” accompanied by the ignition light illuminating, at speed, for model year1968 or later, is caused by an alternator freeze-up. Repair by rebuilding or replacing the alternator.

“GROWL” (like gravel in a tin can) is caused by faulty bearings in the water pump. Repair this by replacing the water pump. Confirm the source by removing the fan belt and starting the engine. If the noise is no longer evident, then the source must be the alternator or water pump!

“WHISTLE” at idle or deceleration but disappearing on accelerating is caused by a vacuum leak between the carbs and cylinder head. Further diagnose by spraying carburettor cleaner between the carb and spacers, spacers and heatshield, heatshield and manifold, manifold and head – if there is a vacuum leak, then the carb cleaner will change the idle speed.

“POPPING” from exhaust during deceleration is caused by incomplete combustion exacerbated by holes in the exhaust or a faulty gulp valve. Repair this by leaning out the mixture, repairing the exhaust, or working with the smog system.

EXHAUST NOISES

“JINGLES or ZIZZES” at rest or at speed are caused by loose clamps or brackets. Exhaust noises will evidence themselves at speed or at rest if the engine is at the same RPM.

GENERAL NOISES

“TINKLY RATTLE” is caused by loose glass in the outside rear view mirror. Repair this by removing the plastic surround, then fitting a sponge or foam to load the glass.

“RATTLES” can be caused by loose chrome bumper overriders, loose grille, loose headrests, or seatbelts. Grab and shake each component of the car – the loose one(s) will be obvious.

“NEE-NEW NEE-NEW” is a police siren or emergency vehicle. Pull over to get out of their way.

“Oh Noooooooo!” is the MG owner’s panicking wail when they’re handed the repair estimate.