Drive it forever: Unresolved brake caliper issue

Dear Mike: When I took the brake pads from the front caliper, I noticed that the mark left by the caliper piston edges on the pad shim was two-thirds of a circle and the other third of the circle just faded away. It appears that when the brake pedal is depressed, the piston pressure doesn’t catch the whole of the brake shim, perhaps because the brake pad or the caliper assembly is not parallel anymore.

What could cause this behavior? What should I do in order to put it right? Shouldn’t I bother about it?

A: The leading edge of the brake pad gets a better bite on the disc than the trailing edge, so some evidence of tapered wear and differential pressure against the piston is normal. I’d check the state of the sliding pins or keyways for free movement, lubricate them properly with high-temp grease, button it up and not worry about it.

Dear Mike: I have a Rover 216 SLI. In the past three weeks the car has stopped as though it were running out of petrol. The first time it started again straight away, but a week later it ground slowly to a halt and restarted five minutes later. I went to a garage and they replaced the fuel filter, which was apparently full of gunk but the mechanic was not sure what it was.

I thought the problem was fixed, but two days later the car did it again. The car did not start for 15 minutes so I had to leave it overnight. It started again the next morning. I blasted it along the dual carriageway in case there was dirt stuck somewhere, but it ran out of water. I topped it up and it has been using water quite quickly, approximately half a liter a day. White smoke has been coming out a bit more than usual.

I have put some fuel injection cleaner in the petrol. It was OK for a couple of short journeys but the light came on again on my way home today.

A: Using water plus spewing white smoke equals a blown head gasket.

Dear Mike: Can you please advise what 442 means? I thought it meant that a car had a 400-horsepower engine, with four-barrel and dual exhaust.

A: The legend is that 4-4-2 (as in Oldsmobile 4-4-2) stands for four-barrel carburetor, four-speed transmission and dual exhaust.

Dear Mike: I have an ‘87 Mercury Grand Marquis with a 5-liter engine. The oxygen sensors need to be changed but they are badly seized in the exhaust manifolds. Is there any trick or tool to remove these old oxygen sensors? — P.E.

A: No secret. They do make special sockets to fit better, with a cutout for the leads. After you have one, or at least a socket that fits well after you’ve cut off the leads from the old sensor, it’s simply a matter of cranking in enough torque.

Dear Mike: I have a 2000 Buick Regal, silver in color, with a light gray leather interior. In some lighting conditions, a reflection of the top of the dashboard appears on the windshield, interfering with forward visibility. What can I do to dull the top of the dash or minimize this reflection? Thanks.

— B.S., Media, Pa.

A: You don’t need to make the surface duller - you need to make it darker. Velcro a piece of dark cloth to the dash. I know it’s tacky, but you can remove it when the conditions permit. Dashboards should be a dark color.

Dear Mike: I was changing my oil and put in a bottle of Lucas Oil Treatment but forgot to replace the oil, and then drove about a mile before the truck stopped - the engine had seized. I’ve put some tranny fluid in. It’s a four-cylinder Chevy S10 1988.

Would you please give me some advice on anything else that may work? I saw something on your Web site about warm brake fluid. Thank you, I will not live this one down!

A: Lemme get this straight: You ran the engine without any oil until it seized solid. And you want to know what kind of solvent will free it up.

Sigh. Your crankshaft has welded itself to the rod bearing shells. The rod shells are now turning inside the big ends of the rods instead of sliding over the crank journal. You’ll need to remove the crankshaft and have it reground to a standard undersize. The rods will need to be replaced. The pistons probably have big scuff marks on the skirts, so the cylinder bores will have to be bored oversize and new pistons fitted. And I’m not even going to go into the damage to the cylinder head.

My suggestion: Buy a used engine and install it in your truck.