I never miss your column I have a problem with...

Dear Car Talk

Dear Car Talk | Jan 01, 1994

Dear Tom and Ray:

I never miss your column! I have a problem with my '72 Eldorado Cadillac. It starts up on the coldest days, but when I take it for a drive, and then turn off the motor to go shopping, it won't start when I come back. It sounds as if I have a bad battery. Then after about half an hour, it starts right up. What could cause this? The battery is new.

TOM: You never miss our column, huh? That's one of our problems, Ann. Whenever our column doesn't appear, no one misses it!

RAY: Anyway, you may not know this, but hot engines can actually be HARDER to start than cold engines under certain circumstances.

TOM: For example, a bad starter could be responsible. As you may remember from your high school physics class (I didn't remember, but my brother told me), electrical resistance increases as temperature increases. So if the starter (which is an electric motor) is going bad, and is drawing too much current, it won't turn over as easily when the engine is hot.

RAY: So if it IS drawing too much current, a new starter may help. But on the other hand, the starter may be drawing too much current to compensate for some other hard-starting problem.

TOM: And the problem you're most likely to have with an old, carbureted gas-hog like this is excessive carbon build-up on the pistons. When gasoline burns--especially when it's not burned completely--carbon (or soot) is produced. And over the years, that carbon accumulates on the pistons and increases the engine's compression ratio. That makes the car harder to start, especially when it's hot.

RAY: There are several ways to reduce the carbon. The best--and of course, most expensive way--is to have the engine taken apart and "de-carbonized." But before you resort to that, you might want to try one of the gasoline additives available for this purpose. Two that have sometimes worked for us are BG Industries "44K," and Chevron "Techron."

TOM: The other thing that contributes to carbon build up is frequent, short trips. So the other thing you can do is try taking this car on a good, hard drive every so often. Take it out on the highway once a week, and run it at 55 mph for at least an hour, if you can stand it.

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