wet engine air filter

[Melorene]

opened the left outside rear door covering the radiator to get to the engines air filter to check and clean it and found it very wet with some water laying under it in the container..I noticed that the air scoup on the sidejust behind the bedroom slide that feeds air to the engine has the cups facing the front, I guess to get a lot of air to the engine via the air filter but it can also collect rain water and get the filter wet..should the air scoup be facing to the rear or is it normal for the filter to get wet? thanks, Mel

[EngineerMike]

Mel- the filter should be able to get wet & dry out repeatedly. driving the the driving rain the intake will be full of road spray pretty much regardless of what you do, so the filter will get misted. Shouldn't be a problem.

[Melorene]

Thanks Mike. I thought by being that wet it would block the air flow..guess I need to check to see if their is a drain hole in the filter container for the water to leak out of. Had it in front of the fire place all night to dry out.. thanks again. Mel

[Old Scout]

You didnt mention the model year of your coach but on my 03 there is a moisture drain valve mid-way between the air inlet and the filter canister. Valve is one-way and automatically collects and drains any moisture that is drawn in the inlet but doesnt let air in.

[Melorene]

My MH is a 2008 34 with just 2 slides on the driver side..how do you access the valve? Take off the chrome scoup on the outside? thanks for the reply, Mel

[jerry davis]

There is no valve. The water drain consist of a 2 inch diameter 4 inch long pipe positioned on the bottom of the large air intake pipe that goes from the intake to the air filter. On the bottom of the catch pipe is a rubber piece that allows water to drain out while keeping water from coming in. Nothing to turn on or off or on.

[Melorene]

So, Jerry, you say the 2" pipe is mounted to the bottom of the large cylinder that the filter is in and drains out the water which could collect under the filter which also means that the filter could get wet but the water should drain out the 2" pipe! I did not see such a pipe when I had the filter out but will check again..

[jerry davis]

The drain pipe is located on the intake line half way between the filter housing and the air intake that is on the outside of the coach.

[spike45]

Originally Posted by EngineerMike

Mel- the filter should be able to get wet & dry out repeatedly. driving the the driving rain the intake will be full of road spray pretty much regardless of what you do, so the filter will get misted. Shouldn't be a problem.

You could not be more wrong. As a service engineer for a filter company, wetting air filter media accomplished the undesired outcome of washing the accumulated dust from the media fibers into the engine. Air filters are not like liquid filters. Air filters work best in dry environments and rely on accumulations of dust to increase the removal efficiency. Repeated wetting is like cleaning the filter repeatedly. Air cleaners remove 99.9xx% of the dust when the initial 'dust cake' builds up in the first 25 hours after an installation (25 hours of highway miles, not idling). After the initial efficiency phase where they typically are at 99.300%. Wetting prevents the shift to the high efficiency range. You may not think this is significant but look at it like this. For every 100 ounces of dust the intake sees, a new filter removes 99.3 ounces. When the filter shifts to the H.E. phase, it removes 99.9 ounces. An engine the size of a Cummins ISL, CAT C9, C12 would be dusted with as little as 5 ounces of ingested dust. Eventually, that dust amount will be ingested through excessive filter replacement, filter cleaning and reuse and filter 'washing' by ingestion of rain water.

[RJay]

Originally Posted by spike45

You could not be more wrong. As a service engineer for a filter company, wetting air filter media accomplished the undesired outcome of washing the accumulated dust from the media fibers into the engine. Air filters are not like liquid filters. Air filters work best in dry environments and rely on accumulations of dust to increase the removal efficiency. Repeated wetting is like cleaning the filter repeatedly. Air cleaners remove 99.9xx% of the dust when the initial 'dust cake' builds up in the first 25 hours after an installation (25 hours of highway miles, not idling). After the initial efficiency phase where they typically are at 99.300%. Wetting prevents the shift to the high efficiency range. You may not think this is significant but look at it like this. For every 100 ounces of dust the intake sees, a new filter removes 99.3 ounces. When the filter shifts to the H.E. phase, it removes 99.9 ounces. An engine the size of a Cummins ISL, CAT C9, C12 would be dusted with as little as 5 ounces of ingested dust. Eventually, that dust amount will be ingested through excessive filter replacement, filter cleaning and reuse and filter 'washing' by ingestion of rain water.

Hi Gary,
Good post. I recently changed my air filter because it was the original and I was concerned that due to age the filter element would begin to deteriorate and the engine would start to ingest filter particles. I only have about 8800 miles on the engine and the air filter indicator showed I had a ways to go before it red lined. Is the deterioration of the filter element due to age a problem and is the air filter gauge an accurate indicator of when to change the filter regardless of age? Based on what your saying a dirty air filter at the time it's normally removed is the most efficient for removing dirt but it's change because it effects the air/fuel mixture?

[spike45]

Originally Posted by RJay

Hi Gary,
Good post. I recently changed my air filter because it was the original and I was concerned that due to age the filter element would begin to deteriorate and the engine would start to ingest filter particles. I only have about 8800 miles on the engine and the air filter indicator showed I had a ways to go before it red lined. Is the deterioration of the filter element due to age a problem and is the air filter gauge an accurate indicator of when to change the filter regardless of age? Based on what your saying a dirty air filter at the time it's normally removed is the most efficient for removing dirt but it's change because it effects the air/fuel mixture?

Shelf life of Fleetguard air filters (before sale) is 5 years. There is no reason to think that in use it is any different. Only ingestion of water does it become a possible issue then to a limited degree as to filter integrity. Restriction indicators are the only way to measure filter life used. Most graduated gauges that have the locking feature where you can see the degree of restriction have a red zone at 25 inches water. If you change at the 20 - 22 inch range you are good to go. Changing at anything sooner allows for more ingested dust per the reasons I stated in my first post above. Even if you changed your filter at 25 inches or more, until restriction is above 30 inches does it affect the MAP sensor and force a change to the fuel delivery by the ECM.

[RJay]

Gary,
You bring up another good point. If the five year shelf life is reached and the restriction indicator still shows well below the 20-22 inch vacuum range it seems that the filter should be changed. I would think that if a visual inspection of the filter reveals signs of deterioration the damage has been done.

[spike45]

Originally Posted by RJay

Gary,
You bring up another good point. If the five year shelf life is reached and the restriction indicator still shows well below the 20-22 inch vacuum range it seems that the filter should be changed. I would think that if a visual inspection of the filter reveals signs of deterioration the damage has been done.

Product shelf life statements by manufacturers primarily is used to limit unlimited liability else they could get warranty claims for filters that are years old. If you were to buy a nearly 5 year old air filter and run it, I would not expect anything unusual to happen. Filters just do not fall apart with age. Getting wet with rain or snow repeatedly does eventually cause the media fibers to swell thus making the air filter less capable of rated air flow and dust capacity. In your case, if you are not at the change restriction, don't do anything. Just keep checking the Filter Minder restriction gauge.

[spike45]

Engine O&M Guides do not list air filter service interval information because that is not something that is predictable like lube oil, fuel or coolant filter service intervals. Air filters will accumulate dust at varying rates due to ambient conditions depending on terrain, location, traffic, and weather. Because of these varying and complex interaction conditions, air filter service you should be doing is NOT inspecting the filter element to SEE if it is plugged. The most reliable and safe method for determining air filter condition and remaining life is to use a restriction gauge such as the Filter Minder(tm) by Engineered Products of Waterloo, Iowa. This product is now the most commonly used indicator in the engine business, LD, MD, and HD diesel (some gasoline).

How does a Filter Minder Air Filter Service Indicator work?

Restriction indicators are able to measure the small pressure differences between the ambient air pressure and the air pressure on the clean side of the air filter. Most engine manufacturers list the upper limit of air filter life as being 25 inches water, about 1 PSI difference in air pressure. Engine ECM controls measure manifold absolute pressure and adjust fuel rates accordingly. It would appear that most MH operations do not achieve sufficient run time and miles to bring on air filter plugging. If you check your restriction indicator, you may see little movement and conclude that it does not work. This is a common but unfortunate outcome even for large on-highway truck fleet operators who commonly put on 125,000 plus miles per year. For them, with their miles, they frequently change the air filter yearly, whether it is needed or not. For them, that works as they generally keep their units for 4 -5 years then trade them off.

For the MH operator a yearly air filter change is much less desirable as the miles involved are few. Air filters will pass dust when first installed. Usually, it will be during the first 25 hours of normal operation. New air filters are usually 99.3% efficient but after the initial 25 hours the efficiency goes up to 99.8%+ and remains for the duration until the 25 inch restriction limit is achieved. Fewer changes will equate to less dust ingested due to filter service. Any ingested dust is cumulative. Eventually, with enough changes the accumulated dust will reach 4 - 5 ounces, enough to cause cylinder bore and ring wear on a midrange size engine like a Cummins C, ISC, ISL, Caterpillar C9, C12 and comparable engines from International and Detroit.

While it is undesirable to get an air filter wet, the effects are usually short lived. Wetting the air filter will cause the indicator to rise, sometimes to the point of achieving the maximum restriction. It is an easy matter to check the restriction and reset it. Do not change the air filter because of that instance. If it rises to a high restriction level quickly again. Service the element at that time and reset the indicator.

What I am recommending you do for a PM interval for the air cleaner system is to determine that restriction indicator is functioning correctly. If it fails to lock up showing maxium achieved restriction the indicator does you no good. Then you may be forced to change the air filter if you have such doubts.

To test a restriction such as the Filter Minder(tm), operate the engine a low idle speed. Cover the air inlet such that you are inducing an artificial restriction simulating plugging conditions on the air filter. As restriction rises, you should see the indicator rise to some level and hold in that position when you remove the restriction. Shut the engine off. Push the yellow rubber button on the bottom of the Filter Minder(tm). It should drop down to the lowest level. If it does not, the sensing line or small brass fitting is plugged. The small brass fitting on this device has a porous bronze filter. Sometimes they become plugged with dust. There is also a very small orifice hole in the bronze filter fitting. It has been known to plug. If the gauge does not reset, remove it and the brass fitting to clean the fittings. Blow them out with compressed air and use of some solvent or even water. When you re-install the gauge, be careful not to see how strong you are. The Filter Miner(tm) now is made with a straight thread and o-ring seal. It can be hand tightened easily. If you have the earlier style, it has tapered pipe thread. It was easily possible to over-tighten that gauge and crack the housing.

What if the gauge does not lock up during the restriction test? In that instance the gauge is faulty. Replace it.

For some there may be the original restriction gauge from Donaldson. It has a red flag indicator with no means of showing advancing restriction. I would recommend replacing that gauge with the one listed above.

That is all there is to PM interval based air filter maintenance. You should periodically check the rubber boots and band clamps. The rubber boots and elbows on the clean side of the air filter must remain pliable for the band clamps to be able to seal. Due to heat and time, the rubber will take what is called a 'compression set' and become hard. Removal of those boots and connectors and re-installing may not result in the same level of air tight seal that you need to prevent dust ingestion. This is especially important if your air cleaner is a Far Ecolite or any replaceable housing air filter. Tightening the clamp may make the clamp tight but the boot hose does not clamp onto the air housing.