Drive it forever : You’ve got yourself a leak

Dear Mike: I have a 1995 Ford Taurus with a 3.0-liter engine. The engine pulses at idle. It seems to almost stall, then goes back to normal. This happens every few seconds. While I’m using the gas or driving, it doesn’t happen, but when I slow down for stop signs the lights will dim, come back up, dim, come back up, and so on. What is going on?

A: This is almost certainly the result of a vacuum leak or a leak in the duct between the mass airflow sensor and the throttle body.

Start by carefully inspecting for leaks on all the ducting and vacuum hoses you can get to. Listen for a hissing noise. A piece of garden hose used as a stethoscope helps pinpoint the hiss, and keeps stuff like your necktie or fingers out of the fan or belt.

If you can’t pinpoint any leaks, spray a short burst of carb cleaner near any suspected leaks. If you spray near a leak, the idle will change for a few seconds as the cleaner is sucked into the intake and burned. Don’t set yourself or your car on fire while doing this.

Dear Mike: I have a 2001 Ford Escape with 66,000 miles on it. Just recently the driver-side power window began to squeak — sounds like fingernails scratching a chalkboard. It first began just when I rolled the window up when it was wet. Now it squeaks when rolling it up or down, wet or dry, in hot or cold weather.

I’ve tried cleaning some of the weather stripping, using a cloth wrapped around a credit card to brush out any debris. But that hasn’t worked. Is there anything I can do to stop this annoying scratching/squeaking sound?

A: Try silicone spray on the gaskets and in the channels where the window goes up and down.

Dear Mike: In 2006 I purchased a 1994 Ford Ranger with a 2.3-liter engine. As a precaution I changed the timing belt along with associated items, including a new thermostat. The engine started running very cool, with the temp needle never getting further than the first hash mark. I replaced the thermostat with a genuine Ford part, but the problem still exists.

What have I done wrong or overlooked?

A: I’d start by using my infrared thermometer or a scan tool to verify the actual temperature in the cooling system. It should be near 200 degrees after a decent warmup. If you’re not seeing this, time to replace that new thermostat with one that actually works — or at least check it.

Dear Mike: I recently purchased a ‘57 Porsche Speedster replica that was built in 1998. It has a 2007cc air-cooled Type 1 VW motor with dual 42 millimeter two-barrel Delorto carbs.

After I drive the car, and park it in the garage, there is always a strong gasoline smell. There are no leaks that I can see. After a few days the smell subsides and eventually completely goes away. Do you have any idea what might be causing the smell? It has been quite some time since I have driven a car with a carburetor.

I thought that perhaps the gasoline left in the float chambers of the carbs might be evaporating, as I believe they are vented to the atmosphere. Is there anything that could be done to eliminate the smell if this is the case? Has this been a problem with the old carburetor-equipped engines?

A: I remember carburetors …

Your aftermarket carbs probably use a foam air cleaner instead of a plenum style with a paper filter element. This foam filter won’t trap any of the fuel vapors from the float bowl vents. Heat from the engine is hastening the evaporation of fuel from the float bowls. This is exacerbated by the higher vapor pressure and aromatic smell of today’s reformulated gasoline.

My only suggestion is to use an electric fuel pump, turn it off a block or so away, and run the carbs dry before parking.