Getting logo off vehicle can be tricky

Dear Mike: The dealer from whom I purchased my 2005 Ford Explorer attached a chromed advertising logo on the rear of my vehicle. I’d like to remove it, but it’s attached very firmly with double-sided tape.

Is there a way to remove it without causing damage to the paint?

— J.M., Colorado City, Colo.

A: There are several products I’ve used. Whichever you choose, work somewhere warm, but out of the sun.

Goo Gone will eventually soften the tape, but it might take a few hours. Lacquer thinner will work faster, but it evaporates rapidly; you’ll need to keep the tape wetted for at least 10 minutes.

The best product I’ve used for this is 3M Woodgrain & Stripe Remover. You’ll find it at an auto parts store or paint store that caters to the automotive body shop or detailing business. This aerosol product will soften the tape fast.

The factory enamel on your truck shouldn’t be affected by any of these solvents, but I would keep these products away from rubber gaskets and plastic bumpers. Once the solvent works, you should be able to peel the logo off by hand. Try helping it along by sliding an old credit card underneath to slice the tape. Clean up the tape residue with more solvent or a 3M Stripe Off Wheel.

But if I were you, I’d just take it down to the dealer and make them take their advertising off my car.

Dear Mike: My father has a 2003 VW Passat with the W8 engine, and he uses 89 octane fuel instead of the 91 recommended. He says the knock sensor will adjust the engine timing to prevent knocking and engine damage. I contend that even if the driver doesn’t hear pinging, that doesn’t mean that it’s not occurring, and can lead to engine damage.

Can this lower-octane fuel damage his engine?

— F. W., Leonardtown, Md.

A: Your father will not damage his engine running any gasoline he can get in the United States, which might be as low as 87 in some areas. The knock sensors — many engines have more than one because they are bolted to the head, not the block — will sense the rapidly building pressure waves caused by gasoline igniting prematurely inside the combustion chamber. The engine-management computer will retard this spark and prevent this condition.

The system is good enough at this to preclude any damage. The downside is that fuel economy will suffer from the retarded timing, making his bargain low-grade fuel less of a bargain.

Dear Mike: I’ve built a lot of engines over the years, but they’ve all been in antique cars. I was helping a friend assemble an engine for his foreign car, and he had the wackiest technique for torquing the head bolts. I swore he was going to break them clean off.

Are head bolts that much stronger today?

—T.R., Chicago, Ill.

A: Traditionally, head bolts were torqued in stages up to their final value. Then you ran the car for a while and torqued the bolts again. The object was to get all the bolts tight enough to make the head gasket seal.

Times have changed. Modern engines have aluminum heads and sometimes aluminum blocks. Head gaskets are asked to do more because of the higher rate of expansion of aluminum compared to iron. This means more consistent clamping force is required.

Many new-technology engines use a “stretch” bolt. It’s tightened to the point at which it deforms plastically — it stretches and won’t return to its original length after it’s removed. Thus, the amount of stretch has to be controlled very carefully.

Conventional torquing is too inconsistent because much of the torque you apply goes into overcoming friction in the threads and against the washer under the bolt head. The smallest irregularity or burr in this area raises the friction — and that bolt will be a little looser than the others.

The answer is a technique called torque-plus-angle. Torque all the fasteners in a couple of stages to a relatively low value, far lower than the point at which friction is an issue. Then, one at a time, turn the fasteners in one smooth stage to a greater angle, generally between 60 degrees and 120 degrees. You can get a torque wrench with a protractor built in or an inexpensive adapter for your existing torque wrench.

Incidentally, every time I use this method it scares me silly because I’m sure the bolt is going to snap and shoot out of the hole — but it never does.