C 12 505 fuel efficiency

[Robert Mielenz]

We are considering a newer coach, Am interested in the fuel MPG for this engine. We would appreciate any input from  C 12  505 HP engine owners. Pluses and problems specific to this engine. Thank for your input.

[Bill Sprague]

A good reference and background document was written by Cat a few years ago.  I tried to find it in our BAC Coach Assist but didn't.  Try it here:

http://prevostcommunity.com/PDF/Motor%20Home%20Fuel%20economy.pdf

[Fred Cook]

Robert, I set my trip meter to zero when I purchased our Beaver last year.  According to Silver Leaf VMS our coach gets 8.5 MPG.  I also checked it the old fashion way, noting the mileage at fill up and dividing the gallons into the miles driven following the next fill up and it was also right at 8.5 MPG.  Ours is a C12, 455 HP with a side radiator with an internal water pump.  The motor continues to operate normally (minus the alternator) even if you bust a belt.... which happened to me a few months ago. A CAT mechanic once told me the C12 was the best motor CAT ever made.... might get some debate from others on this forum on that LOL.

[Bill Lampkin]

The Aladdin system in our '05 Beaver says 5.5 mpg since new. C-13.

[Robert Mielenz]

A good reference and background document was written by Cat a few years ago.  I tried to find it in our BAC Coach Assist but didn't.  Try it here:

http://prevostcommunity.com/PDF/Motor%20Home%20Fuel%20economy.pdf

Great article!

[Frank Bergamo]

Robert, my C-12, with tag axle, will get 7-7.5 MPG depending on speed of 60MPH to 75MPH. Generator and Aqua Hot usage must be considered for accurate MPG. As far as pro's and cons of the C-12, the coolant filter hose location, being next to exhaust pipe can be a problem. That topic has been addressed on forum many times. For my money, the C-12 has better fuel efficiency than any of the big motors. For Beaver motorhomes, the C-12 was used thru 2004. The 2005-2007 mainly use the C13. There are some C-15's used in 2007 and up. If you are looking for fuel economy, the C-12 is your motor. If you are looking for HP and torque, the C-13 and C-15 would be my choice. Hope this helps.

[Jerry Emert]

Mine gets an average of 7.0 using the Aladdin.  I don't track it any closer than that.  I just don't care a whole lot.  As far as problems I haven't had any in five years and I hope this doesn'y jinx it!  LOL
Jerry

[Steve Huber Co-Admin]

Bill,
The article you posted is also available in "Common Problems" (Technical section) of the BAC home page. It is titled "How to Improve Fuel Mileage From My CAT Engine".
Steve

[Doug Allman]

If you get Dave Atherton to do a diagnostic read out on your engine you will find the actual mileage it is getting, and numerous other things. That read out is specific to the mileage of the motor and you do not have any aqua hot or generator involvement to deduct.
Our C-12 505 in our 2004 Marquis on several over the years readouts stayed right at 7.75 mpg while towing a crew cab F-150 always fully loaded with firewood on trips from Michigan to Quartzsite. Numerous other items in the cab also. I drive most always on interstate from 68-75 mph as I like to get from A-B so you can start to enjoy camping in your Beaver even though I have been told you do not camp in a Beaver on this forum.
The C-12 is one of the last great diesels that CAT built prior to having to use DEF fluid. Just be sure you are getting Dave to do a diagnostics readout so you know what is going on in your motor. While you do not have a warranty it is a much bigger deal to know thru a diagnostics read out if you need to do maintenance on any part of that motor before it gets to a real expensive problem.
If you ever trade it or sell your coach that info printed on a CAT readout to the new Owner will seal the deal for the price you want. IMHO it doesnt get any better than that for piece of mind and $$$ value. A Beaver with an inoperable motor is not worth a whole lot.

[Mike Shumack]

There is a fun to watch You Tube video by a CAT mechanic on the "Best CAT engine" -- if you just want to know the best hd CAT engine, jump to the 9:30 minute mark.
'
https://www.youtube.com/watch?v=igDWcKX-a-4

[Lee Welbanks]

The C-12 is a good motor but the boss of the Cat truck big engines is the C 15 6NZ hands down the best truck engine cat made, it can be boosted to a 1000 hp and live running down the road. In that youtube video go the the 12:15 mark. This is the motor the O/O'ers use in their glider kits for a new trucks.

[Bill Sprague]

Bill,
The article you posted is also available in "Common Problems" (Technical section) of the BAC home page. It is titled "How to Improve Fuel Mileage From My CAT Engine".
Steve

You are right.  I didn't dig far enough.

Bill

[Dave Atherton]

Gentleman, depending on how deep you food is pressed downward to the floor the Cat C-12
Provides a very easy 7 to 9 mpg have many 10 mph readings at 55 mph. There is always a
Question on mileage when doing a diagnostic readout of the engine ECM but facts are facts.
Information is retrieved from engine ECM via caterpillar service tool called Cat ET. and information
posted is correct. Second part of the question the Caterpillar C-12 is a very good engine but
caterpillar also several good models also. Mileage has many variable that can affect fuel milage
That may be better milage for some and less for others so there is not. Set number as per one
engine model to others model  Gear ratio, tire size, air pressure in tires, transmission ratio wind
level travel or rolling grades etc. Dave Atherton Retired Cat Mechanic

[Mike Stuart]

We get 7.7 mpg regularly in our 02' Marquis with the 505hp C-12.  We drive at 65 towing a Honda CRV.  If we slow to 55 we can get 8.3-8.7 mpg, but we seldom do that.  All are correct that the C-12 is a super motor.

[Doug Allman]

I think Jerry has the right outlook on fuel mileage, dont pay much attention to it as we pull in and fill it when it gets ready to need fuel. Then on down the highway again. I dont ever remember checking our LP gas needed to run our brick & mortar house as to how many btu's we were using and so feel the same as going on down the road with the house on wheels. Just keep the tank full.
Only once and that was in the 70's when they were rationing fuel did we set out on a trip and figured if we could only get as far as the fuel we had we would camp there and figure out how to get back home later. Soon as we got out of Michigan we could get more than 5 gallons at a stop so it never was a real issue.