air filter dirty/clean indicator

[Bob &]

We bought a used 2002 34ft Alpine coach last April. We have put on about 6000 miles since.
The air filter dirty/clean indicator has shown
clean for the entire time. I decided to make a
quick check as precautionary measure and what to my surprise the filter almost clogged with
dust and dirt. Started doing some checking, I
pulled the small hose from the neck of the intake canister under the coach (just follow the
hose) to the brass fitting. I sucked on the
hose and the guage worked fine. So I took a
piece of hose and connected it to the brass
fitting and blew on it and guess what? The
brass fitting was NOT drilled out so there was
not any way the indicator could possibly work.
I got my drill index out and got the right size
bit and drilled thru the brass fitting from in-
side the canister using an angle drill. Cleaned
all shavings out and reconnected everything and
carefully reinstalled the dirty filter and the
indicator read dirty. Of course I replaced the
sir filter immediatly. Learned later that some
engines have been blown due to excessively dirty
filters, maybe the little brass fitting without
a hole was the culprit not letting you know when
the filter was dirty. Would be interested if anyone else has found this a problem.


a

[Bob &]

We bought a used 2002 34ft Alpine coach last April. We have put on about 6000 miles since.
The air filter dirty/clean indicator has shown
clean for the entire time. I decided to make a
quick check as precautionary measure and what to my surprise the filter almost clogged with
dust and dirt. Started doing some checking, I
pulled the small hose from the neck of the intake canister under the coach (just follow the
hose) to the brass fitting. I sucked on the
hose and the guage worked fine. So I took a
piece of hose and connected it to the brass
fitting and blew on it and guess what? The
brass fitting was NOT drilled out so there was
not any way the indicator could possibly work.
I got my drill index out and got the right size
bit and drilled thru the brass fitting from in-
side the canister using an angle drill. Cleaned
all shavings out and reconnected everything and
carefully reinstalled the dirty filter and the
indicator read dirty. Of course I replaced the
sir filter immediatly. Learned later that some
engines have been blown due to excessively dirty
filters, maybe the little brass fitting without
a hole was the culprit not letting you know when
the filter was dirty. Would be interested if anyone else has found this a problem.


a

["007"]

Welcome Bob & to irv2 and the Alpine Forum.
Thanks for a informative first post I bet you will get everyone looking.
Enjoy all the forums on irv2 no restrictions and post often.
If you want to be a ALPINE FORUM MEMBER just let us know.
ENJOY you new MH many safe and happy miles.

[RV Wizard]

Bob &, welcome to iRV2.com. Thanks for letting everyone know about the problem with the closed fitting for the filter monitor. I am sure you will enjoy this website and forum. We hope you will be an active participant. GOod luck and stay safe.

[Cruzer]

Welcome to IRV2, Bob. That's good information. As a side note, now that you have a fresh filter it's a good time to check what the reading is. Most systems have some sort of restriction built into the system and will read a few inches right off the bat. The air filters are designed to be replaced when this restriction increases by 15 PSI. On my coach my baseline restriction is 6 PSI, which means that I need to replace the filter at 21 PSI (6 + 15). Every system is different so now's a good time to note that initial reading.

[Gary Arnold]

I also have a 2002 coach and have never had the air filter restriction indicator show any thing but clean ( but living in the northwest we rarely have very much dust, just lots of rain). I have changed the filter 2 times.

After reading your findings I decided to look into the brass fitting on my filter canister. What I found was, this brass fitting has a small filter pressed in to the body consisting of a disk of compressed, extremely small brass balls. I have seen this same type of filter used on furnace oil injectors, gas tank pickups on water craft and snowmobiles. I believe the purpose of this filter is to protect the motor from small particles in the event the hose to the filter gauge is not installed or accidentally removed.
I was able to blow through the fitting but did encounter some restriction caused by the filter.

[Old Scout]

I second the motion--appreciate the explanation of a secondary filter to block dirt from entering if the hose were ever dislodged but dont think my restricter gauge is getting any vaccum thru the hose connect. Guess the best answer is to replace the main filter every couple years and call it good.

[Bigsky]

With the engine running, manually restrict the air flow to the engine with your hands over the air intake. It is not necessary to cut off the air completely to make the indicator jump up if it is working.

Al

[Bob &]

Thanks to everyone for their replies about the
air filter indicator. All replies are of help.
I had to learn the hard way, but at least the
my filter wasn't completely clogged causing the
engine to overheat and cause who knows what kind
of damage. thanks again folks.
Bob & Carole