It has been raining a lot in the past week and the weather has turned miserable… The sky is always dark and it makes it harder to clearly see inside the coach, so I moved outside and decided to replace all filters and considering that the paint on the air filter drum was peeling off, a new coat of paint seemed the right thing to do…

Like most other coaches, this one is fitted with the dual filtration system, as you have two filter, one inside the other. The previous owner managed to write the date on the filters and they where replaced back in 2014. Personally if I had to write on the filter, I would put the mileage as the date doesn’t really help much.

Truthfully, both date and/or mileage don’t really help much at all in giving an indication of the state the filters are in. The only way I know to find out if your air filters need replacing, is if you know the weight of the filter when new. There are small variations between brands of filter but they really are negligible. I didn’t have a record of the weight for this particular size filter, so a new one had to be purchased.

The new filter came at 3.5 kg on the scale, while the old one came in at 4.9 kg. That’s approximately 1.4 kg of dirt trapped in the element. I need to point out that even with the best cleaning intentions, you will never get back to the weight the filter had on day one, but it normally tend to gradually increase as the filter mileage increase…

This mean that (based on the road conditions) and taking the filter weight above as an example, the first time you clean the filter you may get it down to 3.7-3.8 kg and the second time you may get to 4-4.1 and so forth. For personal experience, once the filter has reach 50% increase of its original weight, that in this case it would be around the 5.2-5.3 kg, it has reached replacement time, regardless of the purchased date and/or mileage. Air filters are not that expensive, but why bother to replace one if it doesn’t really need to…