Guy ĎGuidoí Allen

Right, thatís it. From here on, any time I allow anyone to work on complex machinery owned by muggins, Iím going to frisk them for their rattle guns (the correct term is air impact wrench) and remove the offending items until further notice.

I blame pit row race TV broadcasts for their popularity. In an endurance event with the fly-on-the-wall coverage weíve all come to expect, you see a flock of serious folk descending on the car and removing and replacing all its wheels in under 30 seconds (with that wonderful staccato machine-gun-like sound, then standing back with their hands (and tools) held high as the hero of the moment bolts away for another few laps of driving way too fast. Itís a sexy image.

Reluctantly, Iíve come to the conclusion thatís their only (the tools that is) place in life.

Before we get too far into this, Iíll hasten to add that I know and treasure many mechanics. Generally, they understand Ė usually through a combination of instinct and experience Ė things that I can only barely comprehend. No matter how hard I try.

Yes, Iíve rebuilt, restored and even tuned stuff with success. Sometimes.

But, deep down, I know Iím always a nanometre away from spectacular failure and that someone whoís really good at it will do the job faster, easier and better.

And thatís why I get cranky when some wally cocks up the most basic thing with the wrong tool. What got me on to this was I recently decided to treat the Mighty Kingswood to an oil change, just before a long trip.

Itís simplicity personified. Buy oil and a filter from an auto store. Slide a cat litter tray (a few bucks from a discount shop) under the sump and undo the drain plug. With a warmed-up engine it shouldnít take more than a few minutes to drain the oil. Clean and replace the plug, move the cat litter tray to under the oil filter, drop same, wipe a smear of oil on the seal of the new one and wind it in. Job done Ė almost. Just remember to refill and run the engine, and double-check the readings.

All up, itís a 30-minute job (at my pace) that costs sweet FA. Or should be.

In this case it went pineapple-shaped when the drain bolt came out too easily.

Ever the optimist, I hoped it just hadnít been tensioned properly.

No. In fact the thread in the sump was half-stripped and, while I kind of got it all back together, now I have to find an oversized bolt and ream out a new thread. So much for my easy little 30-minute oil-change job.

The only way you could strip a thread like this without noticing it is with a rattle gun. Iím sure it was done with the best of intentions, but that doesnít help.

Itís by no means the worst example Iíve experienced. Another was with an alloy head on a twin overhead cam engine, where literally every cam retainer bolt thread had been stripped because the dingbat working on it got lazy and used the dreaded rattle gun. That cost a bomb to fix.

From the point of view of an enthusiast amateur mechanic, itís a huge breach of trust. If I wanted to screw the engine, I could have done it very successfully myself. Why am I paying you to do it?

I know there are plenty of professional wrenches out there who take pride in what they do, and use the rattle gun on wheel nuts and not much else. For them anything that requires a modicum of delicacy is done by hand, sometimes with the aid of a torque wrench. Which is as it should be.

Funny thing is I own a rattle gun Ė one of those cheap deals you get when you finally go mad and buy an air-compressor for the shed. Itís still in the packet it came in and I reckon thatís where it should stayÖ