Air Cleaner Minder (ACM): DOES NOT WORK

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Air Cleaner Minder (ACM): DOES NOT WORK

February 05, 2017, 03:14:56 pm

My Air Cleaner Minder (ACM) does not work, indicator always sits at ZERO, even though the air cleaner was so dirty on a trip that the rear of my coach and front of the towd were covered in tiny bits of soot.

I have seen many post where others have indicated that their ACM always reads ZERO, and I have never seen a reference to an ACM reading anything except ZERO.

I tested my ACM using a 6 foot length of clear tube bent in a "U" with water in it and determined that it was very accurate.

Note: that a standard manifold vacuum gauge will not work to test the functioning of the ACM because a manifold vacuum gauge is calibrated for inches of Mercury while the ACM is calibrated for inches of Water. ACM full scale of 24 inches of Water is 1.76 inches of Mercury.

I have concluded that the ZERO reading with our ACMs is caused by the way it is installed with a thin six foot long tube connecting the air cleaner case to the ACM which is mounted above the engine, or the small bleed hole in the sheet metal cap on the small end of the filter is too small. My reasoning is based on fluid dynamics causing the vacuum inside the air cleaner to pulsing

Does anyone have other knowledge or ideas about why the ACM on our coaches does not work, and what to modify to make it work?

Re: Air Cleaner Minder (ACM): DOES NOT WORK

Reply #1 – February 05, 2017, 04:22:27 pm

What about remounting the ACM on the filter housing to eliminate that possibility?

Re: Air Cleaner Minder (ACM): DOES NOT WORK

Reply #2 – February 05, 2017, 04:37:05 pm

Our ACM works great. I installed another in the stock location with the actual numbers on the side. In rainy weather, the restriction really goes up. You might want to try a more sensitive model.

Here are the number you don't want to go above for each of our engines:
Examples shown in Inches of Water (H20) and kiloPascals
Engine Diesel, Naturally Aspirated Diesel, Turbo Charged

Detroit Diesel 25" / 6.2 kPa 20"/5 kPa
Cummins 20" / 5 kPa 25"/6.2 kPa
Caterpillar 30" / 7.5 kPa 30"/7.5 kPa

Generic exact copies are available for less but here is Baldwin's gauge: Baldwin AFG38D Direct Mount Air Filter Restriction Gauge | eBay

Pierce

Re: Air Cleaner Minder (ACM): DOES NOT WORK

Reply #3 – February 05, 2017, 05:43:39 pm

Quote from: P. Wyatt Sabourin – February 05, 2017, 03:14:56 pm

I have concluded that the ZERO reading with our ACMs is caused by the way it is installed with a thin six foot long tube connecting the air cleaner case to the ACM which is mounted above the engine, or the small bleed hole in the sheet metal cap on the small end of the filter is too small. My reasoning is based on fluid dynamics causing the vacuum inside the air cleaner to pulsing

There is no flow through the line going to the monitor, so length and height won't matter.

Could be a bad seal, or that there really was not a restriction (just because it is dirty doesn't mean it's restrictive).

Re: Air Cleaner Minder (ACM): DOES NOT WORK

Reply #4 – February 05, 2017, 06:32:28 pm

Mine is mounted right on top of the air cleaner housing and still works--after 27-28 years (even tho I broke it off once and then repaired it with Shoe Goo--what else?)

Re: Air Cleaner Minder (ACM): DOES NOT WORK

Reply #5 – February 05, 2017, 06:37:06 pm

Have seen these indicators on industrial engines for years and have never seen one work as supposed to.Some of the filters were
ready to suck in the engine they were so dirty.My advice, eliminate it ,plug the hose and just check the air filter more often.

Re: Air Cleaner Minder (ACM): DOES NOT WORK

Reply #6 – February 05, 2017, 06:44:16 pm

it is best not to open up the air filter can just for a look see. That is another reason I made my deflector and never worry about the filter getting dirty for at least 3 yrs.
JohnH

Re: Air Cleaner Minder (ACM): DOES NOT WORK

Reply #7 – February 05, 2017, 06:49:08 pm

Best case would be to just change the filter at a certain interval.

Re: Air Cleaner Minder (ACM): DOES NOT WORK

Reply #8 – February 05, 2017, 07:10:37 pm

I have read that the filter actually works better after it has some " dirt " in it. Seems to gain from 95% to something like 98% efficiency. So depending on how picky you are,

Re: Air Cleaner Minder (ACM): DOES NOT WORK

Reply #9 – February 05, 2017, 07:33:38 pm

Quote from: Bob & Sue – February 05, 2017, 07:10:37 pm

I have read that the filter actually works better after it has some " dirt " in it. Seems to gain from 95% to something like 98% efficiency. So depending on how picky you are,

True that filtering efficiency increases as dirt accumulates, and it will filter out finer particles (filters are efficiency rated by the percentage of 3 micron particles they catch).

But it costs more to pump air thru them.

Re: Air Cleaner Minder (ACM): DOES NOT WORK

Reply #10 – February 06, 2017, 01:50:32 am

Quote from: P. Wyatt Sabourin – February 05, 2017, 03:14:56 pm

I tested my ACM using a 6 foot length of clear tube bent in a "U" with water in it and determined that it was very accurate.

Wyatt what was your reading with an homemade manometer which is very accurate, but I assume this was at near engine idle with no load. I have never disassemble an ACM but I would suspect it has a jacking assembly that doesn't return the indicator until reset otherwise it would have little value. Tubing size and length have very little effect on fluid dynamics as there is essentially no flow and and therefore no loss. Replace sensor/indicator only if its like a tell tail tach that indicates peak pressure loss. Air filters are a dynamic animal that vary wildly based on flow and therefore hp and economy.

Re: Air Cleaner Minder (ACM): DOES NOT WORK

Reply #11 – February 06, 2017, 07:49:42 am

Have a Dwyer electronic manometer, very accurate will try it at idle and take some readings.

Re: Air Cleaner Minder (ACM): DOES NOT WORK

Reply #12 – February 06, 2017, 09:02:52 am

Those engine specs are at WOT. Our gauges are tell tale with the reset button at the bottom. If you never run at max boost and full throttle, you likely won't move the gauge. You should make full throttle runs occasionally to test the filter minder. Bits of soot on the towed car would relate to exhaust products, not intake filtration.

Re: Air Cleaner Minder (ACM): DOES NOT WORK

Reply #13 – February 06, 2017, 09:36:10 am

Cummins will tell you to replace the air filter based on the filter minder. As the restriction increases the marker in the minder goes up. It should stay at the highest level it has achieved until it gets reset or if it is leaking. The Cummins shop I go to recommends not checking your air filter by opening it up too look at it.

The difference between the best air filter and the worst is about $30. Make sure you are using one with a metal mesh inside and out.

Wyatt, if your air cleaner is really bad and you have opened it up clean the air filter canister very well and replaced the filter and fix the filter minder. If your air filter fails you suck in dirt, the engine gets "dusted", blowby goes way up, you will get black oily spots on the back of your coach and toad and you will need major engine repairs.

Re: Air Cleaner Minder (ACM): DOES NOT WORK

Reply #14 – February 06, 2017, 10:12:23 am

Working with large stationary engines we had to check the air cleaners every month, some of the reasoning was that was the
easiest way to check turbo play.From what I have read here if you know for sure your indicator works good then go by it, if not
sure then either fix the indicator or check the filter or just replace it at a predetermined point.

I realize what has been said about not checking because of "dirt",but most of these coaches have a separator to catch dirt.If you
actually have a layer of sand/dust around the seal then you are not replacing it often enough.When you disassemble it have a
shop vac going to get the loose stuff.

Re: Air Cleaner Minder (ACM): DOES NOT WORK

Reply #15 – February 06, 2017, 10:21:27 am

You should also check the intake plumbing between the air cleaner and the turbo to make sure a clamp has not come off or something come adrift. Several engines have been dusted this way. Some have used a gas or spray parts cleaner at potential leak spots to see if the RPM changes.

Pierce

Re: Air Cleaner Minder (ACM): DOES NOT WORK

Reply #16 – February 06, 2017, 10:23:13 am

Air filters should be replaced based on EITHER:

Filter restriction/minder reading

OR

AGE. Filters are made of paper/cellulose and resin. They degrade with age. Replace at 3 years, irrespective of filter minder reading. And, if they get wet, they degrade very quickly.

Never remove a filter and bang it to remove dirt or use compressed air to blow it out. Way to easy to crack a pleat and allow dirt straight into the engine. This causes "dusting" and lots of CB's.

Re: Air Cleaner Minder (ACM): DOES NOT WORK

Reply #17 – February 06, 2017, 11:19:14 am

Based on recommendations from Pittsburg power who build racing Diesel engines I switched air filters to a Donaldson Blue Tec.

Woven material. Better filtering. More flow. Better HP.

Re: Air Cleaner Minder (ACM): DOES NOT WORK

Reply #18 – February 06, 2017, 11:47:35 am

Is this what we're talking about?

Re: Air Cleaner Minder (ACM): DOES NOT WORK

Reply #19 – February 06, 2017, 11:52:36 am

Yes, Mike, that is your air filter minder.

Once a year it is a good idea to test it-- remove the vacuum line at the intake end. Suck on it. It should peg max restriction and hold that reading until you push the button on the bottom of the filter minder to reset it to zero. Put the vacuum line back in the intake.

But remember, the air filter minder reading is NOT the "end all/be all".

A broken pleat or poor end seal will allow plenty of air in, so no restriction will show on the air filter minder. But, you would "dust" the engine.

Re: Air Cleaner Minder (ACM): DOES NOT WORK

Reply #20 – February 06, 2017, 03:52:34 pm

Travelling' Man: and Nitehawk:
I am considering moving the ACM to the end of the air filter housing to see it works there.

Pierce:
So your OEM ACM indicator bar never moved, but the new one does!

Krush:
While I agree that there is no continuous air flow through the tube from the minder to the air filter, molecules of air must travel down/from the tube into the air filter case so that the vacuum reaches the monitor. With a pulsing vacuum, I wonder if it is possible that a standing wave (based on fluid dynamics theory) is preventing the vacuum from reaching the monitor.
I wonder this because many postings report no movement of the ACM indicator.

John44:
You said "Some of the filters were ready to suck in the engine they were so dirty"
That is what mine looked like when there was soot on motorhome and towd.
I would be interested in any difference detected by your electronic manometer between the air filter cover and the ACM end of the tube.

Old phart phred:
I was not clear enough in my explanation of the testing I did. It was done on my work bench without the engine running. The vacuum was provided by a horse type hypodermic needle connected to a tee in the tube, such that the ACM and the water manometer saw the same vacuum. I also left the vacuum on all night so know the monitor is not leaking

amos.harrison:
The soot I experienced was from going over the Siskiyou on I5 so lots of WOT. The indicator on the ACM was still at zero. This occurred 2.5 years ago and the new air filter at that time was just replaced last month. I have not experienced soot again. The air filter replaced last month was dirty but did not have the layer of sand the previous one had (from a dust storm in Palm Springs).

Re: Air Cleaner Minder (ACM): DOES NOT WORK

Reply #21 – February 06, 2017, 06:13:59 pm

Wyatt,

Yes, guess the OEM was stuck. I bought one exactly like the one posted but for about a quarter the price. Ebay won't let me go back that far to see where it came from. Found one for about $18 but mine has threads. Amazon.com: WIX Filters - 24801 Heavy Duty Air Filter Service Gauge, Pack of...

I spent about forty five minutes blowing out the old filter but it still pinned the new gauge. The coach runs much better now that a new one is installed. Two cycles use a huge amount of air so the filter has to be in good shape. To get an accurate reading, you have to max the RPM and boost like accererating up a freeway on ramp. . Filter is huge and $65 was the least expensive I found. It's a WIX

Ours is mounted in the engine compartment with the tiny tube. No friction loss here as the zero restriction to maximum gauge travel is only about an inch at most.

Pierce

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Re: Air Cleaner Minder (ACM): DOES NOT WORK

Reply #22 – February 06, 2017, 06:21:30 pm

On a mechanical diesel, soot on the back indicates too much diesel (low numerical air fuel ratio). Altitude also makes it worse. Too much diesel also raises EGTs, possibly to a critical level. On my old bus, I would back off the throttle when I noticed smoke in the mirror.

Pierce

Re: Air Cleaner Minder (ACM): DOES NOT WORK

Reply #23 – February 06, 2017, 08:22:49 pm

Wyatt, as I understand it the filter minder just indicates the maximum difference in pressure from on side of the filter to the other. The more clogged up it gets the higher the reading. If it is working right it never goes down until reset, only up over time as the filter gets more clogged and harder to suck air through.

My ISM11 had the cheapest filter possible (from the PO) with no interior screen. It got wet and much of it got sucked right into the engine and through every other part along the way. It required a major rebuild in the range of $25K. Cummins convinced my insurance company that because it was water damage it was covered under comprehensive. Thank you Cummins. They had seen this before. So a cheap filter costs big time in the long run. $30 more to get the best possible filter.

If you are not sure get the filter changed and the filter minder working. Like Brett says, mine is on a three to four year cycle no matter what the minder says but not less without extraordinary circumstances. Every time it rains I check the duckbill to make sure it is dry. Cummins said that the filters actually get better after a while so changing them once a year on a MH driven mostly on the highway was not doing it any favors.

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