Glenn Torrens finds and fixes a mystery mechanical malady
Do you remember that car-parts place TV ad where ol’ mate is looking for a mystery rattle in his shiny red Holden Commodore SS? After pulling out half the interior and making a huge mess, he discovers the rattle to be from a pair of jangly earrings in the ashtray. Sure, this was a TV ad but you can almost imagine stuff like that happening in real life!
Well, in fact, it does. Years ago a mechanic mate told me the story of a maddening warranty task on a Holden Calais; there was a mystery noise when accelerating and braking – but only sometimes. Everything from the engine, gearbox and rear suspension arms’ and cross-member mounts to the wheel nuts to the strut tops to the seat rails to the brake pads and caliper bolts were investigated, checked, tightened, torqued and tweaked… all while the owner of this new Calais grew progressively more furious.
The cause? Eventually, a 50c coin was found rolling back and forth – but not always, due to a 50c coin’s flat bits – inside the car’s left rear door. Apparently the Calais owner’s kid, sitting in his booster seat, had poked the coin past the top edge of the door trim.
Even though most of my cars are not shiny and new, I like them to ‘work’. For example my farm-find 1979 Commodore; despite its rusty back-from-the-dead appearance and 395,000km, drives beautifully, thanks to fresh suspension and brakes, all-new window seals, tyres, etc. I went as far as re-gapping the doors and tweaking/bending the door frames, to minimise the whissysisshysshh of wind noise by clamping the door rubbers tighter against the bodyshell. Something as minor as a dead glovebox light annoys me… so a knock, clunk, doonk, sizzle or rattle from somewhere in any car drives me crazy!
Recently, I had a mystery noise in my 1989 Mitsubishi Pajero 4WD. As I’ve shared here in Unique Cars recently, my resurrected V6 Pajero challenged me with its fuel injection and a few other problems, but it was only after I began regularly driving my big boxy burgundy bush beast that I discovered a random annoying noise.
I could hear a ‘tenk’ noise on corners: It seemed to be coming from the front… Maybe it was a loose component in the steering? However, I couldn’t feel any clunks through the steering wheel, as I would expect. Sometimes the noise wasn’t there… and sometimes it seemed to be from the right footwell; sometimes the left and sometimes both.
Maybe it was loose body/chassis mounts? I re-torqued all the bolts; finding those in the rear corners to be quite loose. I gave everything in the front suspension a good squirt of grease…
The tenk noise remained…Damn.
Frustrated, I gave the Pajero a brisk drive around the block – including some dramatic swerves and drops over some gutters, like a stunt driver in a crappy 1970s car-chase movie – hoping to make the noise worse so its source became obvious. During this drive the tenk occurred just as I happened to be looking over my left shoulder. With my head skewed sideways the sound, this time, seemed to be coming from the rear seat area, not the front footwells.
Maybe the source of the sound was the rear? Weeks before, I’d replaced the rear trailing arm bushes. Something loose? Each rear suspension arm in these Pajeros has two bolts to the rear axle housing and by leaning on them – like, lying on the ground, gripping the chassis with both hands and pushing with both feet against a breaker bar leaning – I tightened those bolts another quarter-turn.
A quarter-turn… That’s all. Hooray! That tenk noise is gone. Just a little under-done on each of those big bolts’ torque was enough to cause the noise!