It occurred to me that besides seeing black smoke from the tailpipe of the car, there is no way of gauging when the air filter is getting restricted in our cars(without actually pulling the cover off). A nifty thing to have is a restriction reminder. These are used on big trucks and buses and are factory installed on Ford Powerstroke diesels. As the air filter gets plugged, the slight vacuum that is created between the air filter and engine is read on a pop-up gauge mounted on the air filter housing.


Having a gauge makes it very convenient to check your air filter condition at a glance whenever you check your oil. There is a flat spot on the air filter snorkel that makes a great spot for mounting.



Basically, a hole is drilled in the filter housing (I used a uni-bit) and a steel 1/8" pipe-thread union is held in the hole with a welder's magnet or vise-grips. Mig-weld the union in place and paint to prevent rust. It goes without saying that if you are doing this work while the housing is installed on the car, take care to make sure the chips from drilling are caught and fire prevention is practiced! Install a 1/8" pipe-thread nipple in the union and screw on the filter-minder. Start to finish took me 25 minutes.



Finally, make sure all joints at the turbo u-pipe and air filter lid are good and air tight. If air can be sucked in around bad gaskets around the pipe or a leaking grommet at the oil separator, the indicator will be useless. These filter minders can be found at any truck dealer and cost around $25.