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Pro Tip! Check Inside Your Oil Filter!

This article was originally posted at Motoiq:


One of the most important things to do when maintaining an engine used in competition or any sort of hard-driving is to constantly monitor its condition and do preemptive service or maintenance when required. Besides the compression and leak down tests that ascertain the condition of the engines valve and ring seal we often take a look inside the oil filter to search for any remnants of bearing material or other debris.  This is done by cutting the used oil filter open using a special tool and inspecting its insides.  Several companies make oil filter cutters but one shown here that we use is made by Longacre Racing Products. 

Longacre makes a lot of race-specific chassis and other tools that can make your life a lot easier. 

We got our oil filter cutter from Pegasus Auto RacingPegasus is our go-to place for race car specialty parts and tools.  They have fast service and everything is usually in stock.

For competition cars, we usually inspect the oil filters insides at every service interval and it is not a bad idea to do this even in your streetcar.  We inspect the inside of the filter for sure if the car had been run hard, overheated, low on oil or if there has been some sort of issue with oil pressure.  The filter is a depository for debris created inside your engine which makes having a good look at the insides of them when you change your oil or experience some hard use is always a good idea.


We use a filter cutting tool made by Longacre Racing Products.  It makes filter cutting easy enough so you have no excuse not to do it.  The tool has two ball bearings that act like rollers and a cutting wheel that works like a can opener or pipe cutter that is attached to a handle/ cutting wheel depth adjuster.


You simply rest the cutter on top of the old filter like this, adjusting the cutting wheel depth and spinning it around adjusting the cutting wheel deeper and deeper as you spin the cutter around.  It works just like using a plumbers pipe cutter.   The Longacre tool quickly cuts through the filter body in seconds.  The cutter is perfect for this job as it does not make any metal shavings while cutting that might confuse you like a saw or cut off wheel would.


The top of the filter comes right off!  Yes, we recommend doing this over a drain pan because the filter will be full of oil.  It’s a good idea to pour the oil into a clean drain pain where you can first inspect the oil for metallic shavings. A sheen of tiny metallic particles that give the oil in the filter a look of mother of pearl is normal.  These particles are so small that you can’t really see them, they just give the oil a pearly look.  They are mostly small bits of iron and aluminum that come from the pistons, rings and cylinder walls that get worn off in normal use.  A brand new engine will have a lot of this mother of pearl looking oil as it comes from the rings seating and the valvetrain burnishing in.

What you are looking for as bad bits are bigger flakes of metal, shavings or things that look like filings.  These are debris that are probably coming off your engines reciprocating assembly, like bearings, thrust bearing, crank journals and even the rods in a case of a spun bearing.  These sorts of debris are not a good sign.


With the cap cut off the top of the filter, its guts come right out. Here are the internal parts of the filter that need inspecting for metal particles. The filter element, the case, and the stamped sheet metal leaf spring for the anti-drain back valve are all parts that can get covered with easy to see metal fragments.


Here is a close up of the oil filter element.  Inspect the pleats of the element carefully. What you are looking for are shavings which are very bad, these using come from dying thrust bearings or if you spun a bearing and its pieces of bearing material, the steel bearing backing and your block or rods.  Usually, this is accompanied by a big drop in oil pressure and loud knocking noises coming from your engine’s bottom end. Usually, most of the shavings are magnetic.  Sometimes shavings also come from the valvetrain and are from the cam and cam followers. This is usually accompanied by ticking or knocking noises coming from the top of the engine.

The other thing you are looking for is flat flakes shaped metallic particles. These are usually not magnetic. These are coming from the engines bearings and are not a good sign either.


The end of the oil filter case is where a lot of metal debris accumulate.  The oil flow stagnates in this area and a lot of the metal in the oil ends up deposited here, usually, most of the metal debris are found here, often more than what ends up on the filter element. I usually pour this small amount of oil onto a clean paper towel and inspect it for metallic debris then inspect and wipe out the case with a clean towel looking for any metal or other material on the towel.  I also usually look at the anti-drain back valve spring that sits in the bottom of the case to see if there is any material on it as well.

If you see these sorts of particles in the filter, it is probably a good idea to tear down your motor and find their source as there presence means that something bad has happened or is in the process of happening and if the motor is torn down and repaired now, a catastrophic and much more expensive failure can be avoided.

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