Several motorhomes we're interested in have these various Cat engines. (I'm not trying to avoid Cummins, it just turned out that the coaches we've found had the Cat engine.) The C12 will clearly provide more power, which is not so important to me – we don't plan extensive travels at high elevations out west and I'm content to go slower with less power up the shorter hills here in the east.What are the advantages of the Cat 3126E vs. Cat C7 vs. Cat C12? In each instance, the coach is between 36 and 40 feet and relatively little difference in weight. I'm more interested in reliability, maintenance costs, fuel costs. Looking for a relatively economical and trouble-free engine.Thanks,Wayne

I have a C7 and live out west. We are not driving in the Indy 500, so going up hills is not a speed race. I manage to maintain 65 over the Grapevine. My BIL has a 3126 in his, and he can stay with the flow also. The C7 and 3126 get around 8-9 MPG, so budget diesel accordingly, and both will get less if you you have a lead foot. As for maintenance, I get the oil, oil filters, and both fuel filters changed yearly at a nearby Oasis Freightliner Dealer, which also includes a generator service, and DOT Check (DOT Check is not required, but they check the slack adjusters, brakes shoes, etc) and this past year it was $600. You will need to budget in every 5 years or so, to change out the rear axle, front axle, radiator fluid with thermostats, and tranny service. Every 7-8 years you also need to figure in tires, and with no tag axle will run you between $2300 and $7,000 depending on the brand and size, so it pays to shop around. I also put back $50 a month for what I call misc maintenance, air filter ($67 from Freightliner), batteries, windshield wipers, and other minor little things that may be done one year and not the next.

I had a 36' DP with the 3126E (330 hp) and it did fine. We traveled out West twice and while we were never the first to the top of the hills, we always got where we needed to go.The CAT's will need valve lash adjustments at about 40K and 100K miles.

My 3126E has served me very well, and my chassis has been bullet proof. I have it service as per the manual. Never felt under powered, and does just fine on mountain roads, I'm never in a hurry to get anywhere. I have gotten 9-10 mpg at 55-60 mph regularly.

Do a google search on CAT ACERT engine problems and then decide if you want a C7 or a C12.

Ivylog wrote:Do a google search on CAT ACERT engine problems and then decide if you want a C7 or a C12.If you do some reading, you will find the failures started when they introduced EPA emissions in the 07 engines. Most of the ACERT failures and lawsuits involve C13 and up engines, basically those with Clean Gas Recirculation, Twin turbos, and the CAT Regenerative System (particulate trap). A C7 does not have twin turbo's, CGR, or the Regen System. I don't know if the C12 has any of those systems on them or not.

Cat 3126E vs. Cat C7 vs. Cat C12 | Good Sam Community

smlranger
Explorer
Jul 08, 2013
I had a 36' DP with the 3126E (330 hp) and it did fine. We traveled out West twice and while we were never the first to the top of the hills, we always got where we needed to go.

The CAT's will need valve lash adjustments at about 40K and 100K miles.
UsualSuspect
Explorer
Jul 08, 2013
I have a C7 and live out west. We are not driving in the Indy 500, so going up hills is not a speed race. I manage to maintain 65 over the Grapevine. My BIL has a 3126 in his, and he can stay with the flow also.
The C7 and 3126 get around 8-9 MPG, so budget diesel accordingly, and both will get less if you you have a lead foot.
As for maintenance, I get the oil, oil filters, and both fuel filters changed yearly at a nearby Oasis Freightliner Dealer, which also includes a generator service, and DOT Check (DOT Check is not required, but they check the slack adjusters, brakes shoes, etc) and this past year it was $600. You will need to budget in every 5 years or so, to change out the rear axle, front axle, radiator fluid with thermostats, and tranny service. Every 7-8 years you also need to figure in tires, and with no tag axle will run you between $2300 and $7,000 depending on the brand and size, so it pays to shop around.
I also put back $50 a month for what I call misc maintenance, air filter ($67 from Freightliner), batteries, windshield wipers, and other minor little things that may be done one year and not the next.

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Cat 3126E vs. Cat C7 vs. Cat C12

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