Dear Tom and Ray:
I own an '86 Mitsubishi pickup with a 2.0-liter engine. My problem is a white, milky fluid that gets into my air filter via the valve cover. Once the air filter gets covered in this gunk, the carburetor starts to spit and sputter. Five mechanics have pulled it apart and can't find anything. Any ideas? -- Jack
TOM: I've got one, and you're not going to like it, Jack. It sounds like you've got WBB: Wicked-Bad Blowby.
RAY: That gunk in your air filter is coming from the crankcase. And it shouldn't be there. Crankcase vapors (which form this gunk) are supposed to be purged by the crankcase ventilation system.
TOM: So the first possibility is that your crankcase ventilation system isn't working (you should be so lucky). If your PCV valve is plugged up or if the hose is constricted or collapsed, that could account for the excess vapors reaching your air filter.
RAY: But more likely, there's simply too much vapor in the crankcase for the ventilation system to handle. When that happens, then the vapor can back up and contaminate your air filter, making it hard for the carburetor to get enough air (which is why the engine is sputtering and coughing).
TOM: And why do you have all those extra fumes in your crankcase? That's the WBB. "Blowby" is combustion gases that have "blown" past the rings and into the crankcase, where they don't belong. And while a little bit of blowby is normal and is easily handled by the crankcase ventilation system, when the blowby gets "wicked bad," it can cause all kinds of problems.
RAY: And the solution? This is the part you're really not going to like, Jack. If it's not a PCV valve or PCV hose problem, the solution is a ring job, a.k.a. an engine rebuild.
TOM: Have someone start by checking your crankcase ventilation system to be sure it's working. And hope to your lucky stars that it's not. Because if it is, I see major engine work in your future, Jack.
Dear Tom and Ray:
Over the years, I have enjoyed reading your column every week and have learned a few things from you about cars. As an old shade-tree mechanic, however, I also saw you make a mistake awhile back. "Larry" wanted to know why today's cars are faster, even though cars of the 1960s (like his '68 AMC Javelin) had more horsepower. Your answer had to do with the car's power-to-weight ratio. But that's only partially correct. In 1972, all cars' horsepower ratings, previously reported as "indicated" (or some other meaningless measure), were changed to "net." "Net horsepower" is the true horsepower the engine delivers in the vehicle -- the actual amount of power delivered to the engine's flywheel, transmission or driven wheels, accounting for horsepower losses due to friction and the addition of accessories. As a result of this change to "net horsepower" ratings, the horsepower listed for the 1968 Javelin is inaccurately inflated by today's standards. In other words, those cars didn't have as much horsepower as we thought they did in the '60s. Hope you'll pass this correction along to your readers. -- Victor
RAY: You just did, Victor. Thanks.
TOM: You mean my 1952 MGTD doesn't REALLY have a whopping 53 horsepower?
Dear Tom and Ray:
I have a hypothetical question about the brakes in a car. If someone was to drive a 1991 Olds Delta 88 Royale with the parking brake on for about 10 or 12 miles before noticing that it was on, would that also affect the front brakes of the car? In other words, would the front brakes fail, too, even through the parking brakes are part of the rear brakes on this car? Also, I don't understand how the vehicle -- hypothetically speaking -- can even go 55 mph down an expressway with the parking brake on. Could you answer these questions for me? -- Kevin
RAY: Kevin, you knucklehead! These aren't hypothetical questions. We know you left the parking brake on, drove halfway to your out-of-town poker game and lost your brakes as you were stopping to pick up the cigars, right?
TOM: Hey, it's nothing to be ashamed of, Kevin. We've all done boneheaded things in our lives. Look at me. I agreed to do this newspaper column with my brother!
RAY: Here's what happened, Kevin. When you left your parking brake on, you created a tremendous amount of friction in the rear wheels. And that friction produced heat. The heat, in turn, boiled the brake fluid, which made you lose at least half of your brakes, and with them, a significant amount of your braking power.
TOM: And on some cars (those with dual-diagonal braking systems), the brake fluid at each rear wheel is shared with one of the front wheels. So if your car has dual-diagonal brakes (I don't have one handy today to look at), the boiling brake fluid in the rear could have caused the front brakes to fail, too.
RAY: And the reason you can drive at 55 mph with the parking brake on is that either your brakes are pretty worn out or you didn't have the parking brake fully engaged. If the brakes were new and you had applied the parking brake forcefully, you would have had a hard time backing out of your driveway.
TOM: At this point, you should have the rear brakes inspected, because you may have toasted them. Have your mechanic check for heat cracks in the linings, and if he sees cracking, have new linings installed. And while he's there, have him adjust everything, and make sure the parking brake is working so well that you can never make this mistake again ... hypothetically speaking, of course.
- Got a question about cars? Write to Click and Clack in care of the Journal-World, 609 N.H., Lawrence 66044, or e-mail them by visiting the Car Talk section of cars.com on the World Wide Web.
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