Breather Filter Installation

Breather Filter Installation

Covers:

1990-1992 3.0L V-6 Engine

The Positive Crankcase Ventilation (PCV) system ventilates the air in the cylinder head to equalize the pressure built up in the engine crankcase. The fumes are vented into the intake system to be burned up along with the air and fuel mixture. Although this improves the car's emissions, this results in three problems. 1) The crankcase gases enter the engine along with the air and fuel, cutting down on the amount of fresh, clean air the cylinders receive. Although there's a very small amount, it's always better for fresh, clean air to enter the cylinders rather than engine gases. 2) The engine gases are hot, and will increase the temperature of the air in the intake manifold. Remember, for every 10° increase in intake air temperature, you'll lose about 1% of the engine's horsepower. 3) Worst of all, the fumes contain vaporized oil which coats your intake manifold. When the piston rings begin to wear, blow-by increases and will cause a back up, resulting in the fumes exiting out the fresh air breather tube... where air is normally suppose to enter. The oil in the blow-by fumes will be blown through the intake and coat everything from the breather tube inlet to the throttle body with an oily film. If you have a turbo, this will include the intercooler and turbo. As the oily film builds up, a substantial decrease in performance will occur, including engine problems such as low idling and stalling.

Many Probes with over 100,000 miles on them suffer from excessive blow-by. After cleaning out my GT's intake system of a coating of oil and soot, I looked for a solution to this problem, short of replacing the piston rings. Although a higher flowing PCV valve is usually recommended at this point, it's not a cure. The solution turned out to be reverting the engine to a PCV system from older cars. Older cars took in fresh air through breather tube filters. Removing the breather tube intake from the engine's intake system and placing a filter on the end instead meant that the oily gases would no longer be able enter into the engine's intake system. Repeating the procedure for the PCV valve end of the system would keep the gases from mixing with the fresh air entering the engine. Although a pretty good idea, I'm pretty sure this is breaking emission codes. It's very easy and costs about $10.

Parts Required

Two breather tube filters
Two 3/4" hose clamps
Electrical tape or large screw

Tools Required

Screwdriver

Procedure

Cut the breather tube (air box to front valve cover) at the half way point. Remove the tube coming from the air box.
Install the breather tube at the end of the tube coming from the front valve cover.
Install a 3/4" hose clamp at the neck of the tube to hold the breather filter in place.
Tightly cover the tube connector at the air box with electrical tape. For best results, thread a 12mm screw into the hole for a tight seal.

Filter Part Numbers

Purolator	B43160
AC Delco	FB106
Fram	CA6591
Motorcraft	FA-1047
Wix	46967

This is the original set up.

The cut hose with filter attached.

Results

It took a couple of days for the oil that built up since the intake cleaning to disappear. Since then, the idle has been much smoother. One month after installation, I check the filters. The inner part of the PCV filter had yellowed from the gases. The breather tube filter turned light tan from the oil film. It was nice to know that this crap was no longer entering my engine. I'll probably change the filters every two months (about $3).

After two months, the PCV side started browning from the oil. The breather side was pretty saturated with oil, but not enough to clog or to drip. I changed the original hoses with black ones. Looks better now. I replaced both filters, giving both sides the large, higher flowing filter type.