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1999-2004 Mustang Catch Can Uses & Explanations

Written By: Chris Bowman

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Keep blow-by from entering your intake and damaging your Mustang's motor with one simple mod-a catch can. It's a cheap investment that can save the life of your motor.

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An oil catch can will filter out the oil that gets cycled through the PCV valve and back into your Mustang's intake. This can prevent serious engine damage over time if left untreated, especially on forced induction Mustangs.

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Facts About 1999-2004 Mustang Oil Catch Cans

  • Can prevent oil build up, caused by “blow-by” in the intake
  • Separates contaminated oil from the exhaust gases before being recycled back into the intake to be re-burned
  • Contaminated oil is safely stored in the catch until it is disposed of during an oil change​

A Sticking Mustang Throttle Body or Rough Idle

If your 1999-2004 Mustang is running rough or idling poorly, it could be caused by a buildup of gunk in the intake. This gunk is an oily by-product of “blow-by” which can cause your New Edge Mustang’s throttle body to stick open, creating a host of intake related problems. An easy and inexpensive way of preventing this nasty oily build up from happening is by installing an air/oil separator a.k.a. catch can. The image below is a prime example of what “blow-by” can do to a vehicle's throttle body.

Carbon Build-Up on a Mustang Throttle Body
Throttle Body Carbon Build-Up

What is Mustang Blow-By? – An Explanation

Blow-by, as mentioned above, is a combination of unburned fuel, exhaust gases, and oil that escapes from around the piston rings during the combustion process and enters the crankcase. This oily vapor is vented out of the crank case via a PCV (Positive Crankcase Ventilation) valve to be re-circulated back into the intake manifold. If these blow-by gases were not ventilated out of the crankcase, a number of issues could develop including a gasket leak (a blown gasket), contamination of your engine oil or even internal rust due to the moisture content.

PCV Valve Installed in a Mustang Intake Manifold
PCV Valve

Mustang Catch Cans – The Basics

Now you understand how important it is to remove blow-by gases from your engine, you might be thinking, “Why not just vent it all into the atmosphere and prevent it from gumming up my intake and solve both issues at the same time?” Well, that would be illegal and the Environmental Protection Agency (EPA) would want to have a word with you. Don’t worry - there is a safe, legal, and easy way to solve both problems at the same time: a catch can. A catch can or air/oil separator does what its name implies: it separates out the contaminated oil from the blow-by exhaust gases before being recycled back into the intake to be re-burned. This prevents the used oil from re-entering the system to gum up your engine. The captured oil is safely stored in the catch can until it can be properly disposed of during your next routine oil change. AmericanMuscle carries a wide selection of air/oil separators from JLT, Mishimoto, and Moroso for all 1999-2004 New Edge Mustangs, including the V6, GT, Bullitt, Mach 1, and SVT Cobra models. 

The diagram below illustrates the basics of how a catch can works. The purple arrow represents the air/oil blow-by mixture coming in from the crankcase. It enters the catch can where the oil is collected at the bottom. The air is forced through a media, which filters out additional contaminants, before exiting the catch can as cleaned air (green arrow) to be re-circulated back into the intake manifold.

Inside a Mustang Oil Catch Can

Should You Install A Mustang Catch Can? Yes, You Should.

An air/oil separator is an ideal upgrade for any model New Edge Mustang, including naturally aspirated V6 and V8 engines. However a catch can is an absolute must if your engine has been heavily modified, or if you’re running a forced induction setup like a turbo or supercharger because of excessive blow-by. Hopefully this article has shown you catch cans are a cheap and effective way to prevent oil sludge from building up in your engine’s intake - where it doesn't belong.

Fitment includes: 1999, 2000, 2001, 2002, 2003, 2004, GT, V6, Cobra, Mach1, Bullitt