Poor air intake design, Cat C15 discussion

[Newell1223]

The problem of poor air intake design is wide spread in the motorhome industry. Part of the problem I feel is based on the fact that the air intake system design is left to the MH manufacturer due to the custom nature of the engine fit into the engine compartment.

The video I produced discusses a series of problems which I discovered on my 2008 Newell Coach. These problems I believe are widespread and are responsible for many of the past threads on this site discussing air filter failures, Filter Minder operation and readings which show premature filter failure when the problem is actually based on a poorly designed system.

The video can be found on You Tube here:

https://www.youtube.com/watch?v=bLK-PPd5c0Y

Comments and discussions of your past experiences would be welcomed, and please remember the video is just part 1 of an ongoing project.

Thanks

[CountryB]

Your issue is not specific to Newell.
You should post this in the CAT section - so other Cat owners can benefit or contribute.

I have the C13 and have the same issue. My restriction gauge will show red after a full throttle application (under load).

I found during my research that the C15 installed in the Beaver Marquis had this issue too and Beaver upgraded to the larger cfm filter on later models.

So I swapped my Donaldson Ecolite P537448 (the 1200 cfm) filter to the Ecolite P537449 (1500 cfm). The length and openings are the same but the diameter is different. I bought new mounting straps and had to make some other mods to fit it in. On my Coach the air intake is on the Roadside near the top of Coach. That means the air pipe comes down and goes across the engine to enter on the Curbside. I'm think that piping is creating more restriction and the filter cfm is not as much to blame. I would like to rework this intake piping (from inlet to filter) but have not gotten past the "thinking about it" stage yet.

I do not have any performance complaints. I'm making 45+ pounds of boost under load. Fuel mileage is the same around 5.5 mpg.

I'l be watching your thread and maybe get some ideas from you. Good luck.

[windsorbill]

Newell1223 and Mike

I'm not so sure this only applies to Cat either. Our Windsor with the Cummins ISL, when new, was plumbed wrong with too small of filter and plumbing. I caught it early and Monaco paid to have it completely redone.

I just happen to run into another 06 windsor and we compared engine compartments. He still had the old (smaller) plumbing and air filter.

[Newell1223]

True, I posted this video in a general category because I have seen numerous design flaws in many RV from various companies. I think Diesel pushers tend to be worse as the intake systems are added by the RV maker and not like a Freight liner chassis where both intake and exhaust are designed and built by Freight Liner.

Sorry for focusing on just the Newell issues but it will at least give you the clues necessary to look at your own system.

[Ivylog]

Not only is the air hot from the engine area, it’s very dirty. No way would I not have fresh air from the outside. To use both ends you have to reduce down from 12+” to 7”.

[Ivylog]

When you cut the filter open, cut the left (straight inlet) off 6” from the end. This will give you the reducer to clamp on the other end for straight through.

[CountryB]

Originally Posted by windsorbill

Newell1223 and Mike

I'm not so sure this only applies to Cat either. Our Windsor with the Cummins ISL, when new, was plumbed wrong with too small of filter and plumbing. I caught it early and Monaco paid to have it completely redone.

I just happen to run into another 06 windsor and we compared engine compartments. He still had the old (smaller) plumbing and air filter.

I guess Monaco only fixed those Coaches where the owner brought the issue to their attention.

What was the major change? Piping size (how much of a size change) and/or rerouting?

[Jyrocharlie]

Gulfstream was bad too. Anytime your filter minder turns red with a new filter, that may be the Problem.

[windsorbill]

Originally Posted by CountryB

I guess Monaco only fixed those Coaches where the owner brought the issue to their attention.

What was the major change? Piping size (how much of a size change) and/or rerouting?

Mike,

Yea for sure Monaco only did the ones that owners complained about. I had no issues getting mine done, but I had to bring it to their attention. It's almost like they knew.

They sent me to a place that specialized on engine upgrades. Name is drawing a blank. They didn't re-route anything but upgraded the sizing. My intake is on the left rear corner of the coach. Quite high up. From there they ran a new 8" pipe down to the new 7" filter intake. Then a 7" from the filter to the engine. They had to fab some new brackets. As I recall, the guy told me they had 12 man hours + parts into it.

Originally I had a 6" line going into a 6" filter intake.

My gauge would peg out at 25" every time I put a good load on it even with a new filter, not necessarily throttle WAO.

The only reason I caught it was I ordered a new air filter about 6 months after we got the coach. (still in the 1 year warranty period) I just used the filter number that was in the owners manual, and of course, it didn't fit.

[FormerBoater]

Originally Posted by Ivylog

Not only is the air hot from the engine area, it’s very dirty. No way would I not have fresh air from the outside. To use both ends you have to reduce down from 12+” to 7”.

I am always amazed at how much dust/sand is picked up by the rig and ends up deposited on the engine.



I cannot imagine feeding that hot/dirty air into the air filter without creating major problems.


"Dusting" an engine is a real thing and not a cheap date to remedy....usually will require an in-frame rebuild.

[Newell1223]

Hi DaveS,

Thanks for the comments. Here are some additional thoughts.

Dusting an engine refers to allowing unfiltered air into the engine. While it looks horrible inside the engine compartment the air is actually not that bad. Especially on paved roads. The accumulation of dust inside my lower compartments is just about as bad and I clean them on a regular basis. The general environment of the engine compartment is based on the huge volume of air coming through the radiator hence the bigger concern with increased air temps.

Caterpillar engines are used much more in construction and mining operations than on highways and the filters do a fine job cleaning the air to an acceptable level. That's why I quoted the dust intake tolerance given by Cat. I estimate I'm 1/10th the maximum dust entrainment level.

I am already laying out the hardware to pick up the fresh air from a clean outside position. The bigger concern is picking up air that is warmer than absolutely necessary. I spend allot of time in AZ, NM, FL and all points in between. The surface temperature of Blacktop is 160 F in AZ in the summer. Concrete is about 150 F. the new Newell's have the fresh air intake on the roof of the coach which I think is the best place to pick up air as its furthest from the heat and dirt of the road.

The general opinion in the industry is that cleaner air is always better hence a pre-filter would be a great addition, they can reduce dust and water intake by 80% but it's not workable if it brings my vacuum back to an unacceptable level. As for Temperature, that too must be addressed and will be before the summer heat returns. I'm eyeing a parallel routing next to the generator exhaust of the intake onto the roof. The other option is utilizing the large space on the passenger side of the engine. The big problem is the size of the air cleaner necessary. I'm afraid that none of the Eco type filters will be big enough so I will need to build a custom canister to take 2 cylindrical filters in series. This will require a different fresh air intake routing, so its no use constructing that until I get a final reading of a single Eco filter and calculate just how bad the whole system is.

I just ran across this company, Transducers Direct, (webpage address below) and they may have a Bluetooth vacuum sensor that will give me constant readings during operation. I'll let everyone know if it works out.

https://www.transducersdirect.com/pr...ess-solutions/

[FormerBoater]

Our vintage Eagle has the fresh air intake on the roof under the spoiler.


Piping feeds to a square box before the air filter to catch any rain/water prior to the piping into the filter itself. Duckbill valve at the bottom of the box to drain any water accumulation.




This seems to be a good design as we have traveled through many a Florida downpour with no water ingestion issues.


I think you are on the right track!



Much smaller displacement engine than your C15 (8.3 liter Cummins), but the filter minder does not move at all for the first 10,000 miles of service.



Very interesting/informative discussion!

[CountryB]

Originally Posted by Newell1223

I just ran across this company, Transducers Direct, (webpage address below) and they may have a Bluetooth vacuum sensor that will give me constant readings during operation. I'll let everyone know if it works out.

https://www.transducersdirect.com/pr...ess-solutions/

Filter Minder also has a remote restriction gauge (and several type of vacuum and pressure gauges) Filter Minder® Sensor LED Display Reads Sensor Output Voltage

[Fiesta48]

My DP is a 2015 Fleetwood Discovery 380hp 32k lbs. gets 8.8 mph including gen time and pulling a Accord. I've rattled my brain trying to improve the intake tract. I have modified every vehicle I have owned since 1985. Many.
To date I have added an air scoop which only improved throttle response not MPG. But then my vacuum never goes below 11" water. It did go lower before adding the scoop.
I do not ingest water (drain holes) and hardly any dirt.
After seeing the OP video I'm now thinking I'm fortunate to have bought the RV I did.