What's the right way to clean a dirty engine?

Dear Car Talk

Dear Car Talk | Jun 01, 2009

Dear Tom and Ray:

I have a 1984 Nissan pickup with only 64,000 miles. It runs great, but the engine is so dirty that I am embarrassed to have it worked on. How should an engine be cleaned? Is steam cleaning appropriate? Thanks.

-- Roy

RAY: Well, you're very considerate, Roy. Most people don't give a second thought to forcing their mechanic to fight through sludge and dirt and garbage just to get his work done.

TOM: And that's just the passenger compartment.

RAY: You can certainly steam-clean your engine. Usually, a really filthy, disgusting engine is a sign of an oil leak or three. When oil leaks out, all kinds of dirt and junk stick to it, and the engine becomes bathed in a thick layer of grime.

TOM: So by steam-cleaning the engine, you not only send a signal to your mechanic that you care about your car (and therefore, so should he), but you also make it easier for him to FIND any leaks. When the engine has been cleaned recently, it's a lot easier to see where those leaks are coming from.

RAY: So, go to a car wash or auto-detailing place that offers steam cleaning. It's not something you want to do in your driveway, because the stuff you wash off is toxic, and you don't want it going down the drain and into your local waterways -- or creating your neighborhood's first Superfund site. Find a place that has a grease trap, so they can dispose of the runoff properly.

TOM: And bring a good book, just in case some important electrical component gets steamed under high pressure by accident and prevents the car from starting until it dries out. It happens.

RAY: And then drive around with a clean engine for a week or so before having your car serviced. Your mechanic probably will be able to tell you exactly where the oil leaks (the ones that made such a mess in the first place) are coming from. And he'll have to spend less time at the sink before eating his lunch. Everybody will be happy, Roy.

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