Tuesday, March 10, 2009

My automobile's cooling system and its plastic parts

I've learned a lot about my car's cooling system over the past couple of weeks. There's nothing like the prospect of a melted engine to focus the mind. Typically, I would be content to leave it to the mechanic, but the cooling system has many moving parts, and I'm the one who sees firsthand all the symptoms when driving it in various situations.

At the very least, anyone in my position would have to take careful note of which circumstances triggered certain events. Such diagnostic tips can help the mechanic narrow things down so that he won't charge you as much for diagnosing the problem. Ideally, we'd also prefer that he fix everything that's wrong with a component as vital as the cooling system.

I've had to watch the reading on the temperature sensor, for one. The key is to never let the needle hit the red zone at the top of the temperature gauge. If it does, your engine's head gasket and other crucial parts are in critical danger of melting, distorting, or breaking. The repairs for those problems are much more expensive than those to the cooling system.

When I went to the mechanic this morning, I took in various observations that would help him narrow down the problem and know where to look. I noticed that the fans were going full speed because of the higher running temperature, so I told him that the fans were extremely loud after a short drive. From various sources online, I made sure to observe any difference between city driving and high speed freeway driving, but there was none, so this meant there was one less option to consider.

With the cooling system in my car, things have been failing left and right in a sort of chain reaction as the increased running temperature of the car's engine puts a lot of parts under extra stress. Whatever parts failed and needed replacing were just worn out and should have been replaced long ago. Rubber rings had become as hard as plastic. One plastic pipe had become so brittle from age that it broke off; I had to re-fasten the hose clamp just to keep the engine running cool enough to drive to the mechanic. Metal parts such as the thermostat housing and the water pump showed signs of corrosion; in the case of the thermostat, it wouldn't open to let coolant flow as it should.

The mechanic told me some interesting tidbits while we were ruminating aloud on the absurdity of car makers — including Daimler and BMW — using so many plastic parts all over the cooling system. According to him, the move towards plastic parts is justified by lower cost of materials and making the car lighter so the engine doesn't have to pull as much weight. One thing he observed was the increasing failure rate of newer cars — and he said it wasn't unusual for people with new cars still under warranty to come to his shop with worn out plastic parts.

Suffice it to say, that made me very hesitant about paying a premium for a newer model Mercedes-Benz or a BMW. If I end up buying a new car soon, it may well be a Hyundai, a Honda, or a Toyota. If everyone's using plastic parts, I may as well pay less.

In any case, I'm surprised that my old car has lasted this long, considering the long distances I drive on a regular basis. It's a 1996 Mercedes-Benz C220. I've been very fortunate to have the car running within its prescribed temperature limits, despite all the hand-wringing and pulling over to the side of the road, fraught with worry.

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