Paul Brand: How to use a block heater

  • Article by: PAUL BRAND
  • Updated: January 2, 2005 - 10:00 PM

This story was published Jan. 10, 2004.

QOn last Sunday's radio show, you mentioned block heaters. It got me to thinking about using mine since the cold weather is here and this is the first winter I've had to park outside. Since I've never used the factory-installed block heater, can I start using it now? Or will it send sediment and crud through the cooling system or cause any other problems? Also, if you recommend starting to use it now, how long can I leave it plugged in, several hours? Overnight?

AFunny that you mention block heaters: I asked my oldest boy if his '93 Chevy K5 Blazer had a block heater that he could plug in last Sunday night. He said no, and added that his battery was 'giving up the ghost' and probably would not start the truck Monday morning. He was right, and had to borrow the family Tahoe to get to work.

Don't hesitate to plug in the block heater on your truck. The fact that it hasn't been used isn't an issue. Most 'block' heaters consist of small electrical heating elements mounted into a replacement 'frost plug' installed on the engine block. The heating element reaches into the cooling jacket surrounding the cylinders so that it is directly immersed in the coolant full-time, whether the unit is ever plugged in or not. So, since you've kept up with routine cooling system service, there should be no significant sediment in the system anyway.

Unless temperatures drop to 30 or 40 below zero, set up an outlet timer to turn on the block heater two to four hours before you need to start the vehicle. That's enough time to warm the coolant sufficiently to assist the engine in cranking and starting. By the way, a key benefit of warming the coolant is to warm the cylinder walls to reduce the percentage of incoming fuel that condenses on the cold metal and contributes to non-start/flooded engines.

QI own a '99 Cadillac DeVille with 4.6-liter V8; the car has 36,000 miles on it. Over the past 20 months, the 'service engine' light has come on several times. Each time, the dealer has quickly diagnosed the problem as a fouled No. 3 spark plug. A replacement plug sent me on my way. Last January, the light came on again and the dealer again diagnosed the problem as a fouled No. 3 spark plug. They determined the spark plug and injector were the cause. The plug was replaced and the injector cleaned. My question is what are the chances of this happening again? The car is now out of warranty.

AActually, it is probably still covered by the federally mandated five-year/80,000-mile emissions warranty. And it seems quite logical that a fouled spark plug causing a misfire would lead to an emissions failure, which is confirmed by the 'service engine' light.

What would cause repeated fouling of a specific spark plug? Logically, the powertrain computer should deliver equal pulse widths to each injector, which in turn should deliver equal amounts of fuel. For just one spark plug to foul, the injector is delivering too much fuel because of shorted windings or some other failure, or the injector is delivering a very poor spray pattern because of deposits, or the cylinder itself is developing poor compression and thus inefficiently burning the fuel, or the ignition system is allowing that spark plug to misfire to the point of fouling.

The dealer has addressed the problem by replacing the spark plug and cleaning all the injectors. This is a logical approach to resolving the issue, but may or may not be the ultimate solution. Since the problem is well documented during the original manufacturers warranty, plus the five-year coverage of the emissions warranty, I really don't see this being a question of warranty coverage or not.

If the problem recurs, the dealer should do a cylinder balance test and/or compression test to determine if there is a mechanical issue with that cylinder. If not, the dealer should focus on the injector itself, and confirm proper operation of the ignition system/coil for that spark plug.

QI have a '97 Mazda Protege with 1.5-iter engine. I have been breaking alternator belts left and right lately, and can't seem to see what is causing them to fail. The normal tension ( 1/2 inch of deflection or so) is too tight, and the belt squeals like a banshee and breaks within a short time, depending on how far my son drives the car that day.

AWhy is the 'normal' tension too tight? Mazda calls for less than 1/2 inch of deflection on the A/C belt and about 1/4 inch of deflection on the alternator belt with 22 pounds of pressure applied mid-span. Perhaps the squealing, which may be leading to overheating and rapid failure, is caused by inadequate belt tension. Also, belt alignment is critical. Visually check to make sure all the pulleys driven by that belt operate in the same vertical plane. Use a straightedge or ruler to confirm this if you're not sure. A bent mounting bracket or a pulley with serious run-out could cause rapid belt failure.

Finally, if everything looks good, perhaps one of the belt-driven components is generating excessive drag from a bad bearing, causing the belt to slip and fail.

To submit a question, write to Paul Brand, Star Tribune, 425 Portland Av. S., Minneapolis, MN 55488. Please explain the problem in as much detail as possible and please include your daytime phone number in case I need more information. Because of the volume of mail received, it isn't always possible to send a personal reply.

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