Felt Oil Filter Element

It is now documented to be an ongoing problem, not just a single freak failure. The felt oil filter element is continuing to have repeat failures.

This picture is an absolute mess, and the engine it came from is also an absolute mess. The oil filter in the picture, or what remains of it, was originally a felt filter. This is the type of filter you see illustrated in the Workshop Manual and the Service Parts List. It has been the old reliable filter for decades, preferred by some for the depth penetration filtering and dirt holding capability. In this case, for some entirely unknown reason, it not only failed but also ruined a nearly new engine. See October 14, 2011 report in article OF-100F

Click for larger image

The filter was a Moss 950-510 in the original filter cartridge. As you can see, it kind of melted down into a black sticky sludge which almost totally plugged up the oil pump pickup screen, and the engine is ruined.

On 12/10/2016, Tom Chapple in San Luis Obispo, California USA wrote:
"Recently I had an oil filter failure pretty much identical to that described in OF-100F. I tore the engine apart to find major fragments of metal, a spun center main bearing and otherwise bad news requiring a major re-build of an engine that was entirely rebuild just 13K miles ago. .... I am definitely staying away from felt filters in the future". See report in article OF-100F2

On 12/13/2016, Tom Chapple wrote:
"The above picture is the second filter that disintegrated for me. Upon pulling the filter, I found it 90% destroyed and 1/2 teaspoon of metal filings were sitting in the bottom of the oil filter canister. I installed a new felt oil filter, fresh oil and cautiously drove the car. After 75 miles of driving on the fresh oil & filter, I became alarmed by extremely low oil pressure. Upon tear-down the main and rod bearing were seriously eroded with evidence of metal filings passing through. In closing, for me, it’s no more felt filters".

"As a side-bar, I did purchase these filters through Moss Motors. I took the first of the two filters to Moss via the local British shop where I purchased it. I will soon take the second filter as well".

Now that it has happened again, there must be a reason, and it is predictable that it will happen again, unless someone figures out why it happens and fixes the problem. It may be something like a change of additives in modern motor oil where something new will make the felt material decompose. More likely it is a manufacturing fault of felt material with too low density, or maybe different type material used to make the felt, or insufficient mechanical retention of the felt in the filter element.

Until such time as someone can determine why this happens, and fix it, I can only recommend that no one should ever use a felt filter again.