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What Kinds of Engines Are in RVs?

Buying a motorhome is a heady experience. Selecting the size of the vehicle and picking the perfect floorplan can be exciting and overwhelming at the same time. But one decision that may be more important than all of the others is the type of RV engine. That choice can affect the lifespan of your rig, the cost of fuel and maintenance, and the way you drive it over the years. So, which is it? Do you want an RV engine that is diesel or gasoline-powered?

The Kinds of Engines in RVs

RV engines vary by the size of the rig they are powering. From Class B vans to 45-foot bus-like Class A motorhomes, you’ll find both gasoline and diesel engine options.

Gasoline Vs Diesel - 4 Major Differences

Common Gas Engines

Gas engines run the gamut depending on the size and type of RV. From V6 engines to large Ford 460s, several gas-powered ones are used successfully in recreational vehicles.

Vans tend to have V6 engines like those used in the Ram ProMaster and Ford Transit vans. Even some older small truck campers used four-cylinder engines.

Class C campers almost exclusively use V8 and V10 gas engines. Larger Class As usually use a V10 engine, although many older big rigs have a Ford 460 or Chevy 454.

One of the latest popular gas engines is the Ford 7.3L V8. Almost all of these gas engines are available both in motorhomes and their van, or truck counterparts.

Common Diesel Engines 

From a camper van size to a diesel pusher, you can find several sizes of diesel-powered engines. The Class B van has become extremely popular due to the Mercedes Sprinter chassis with four- and six-cylinder options. Many new Class C RVs use the same Mercedes diesel engines as well.

The most common diesel make offered in larger motorhomes is Cummins. From the ISB that is used in dodge trucks up to their X15 Cummins can power any size RV.

Some top-end luxury motorhomes offer Volvo or Detroit Diesel engines but these are less common. In the past Caterpillar engines were common but they exited the RV industry in 2007 with new emissions requirements.

The big diesel engines found in large motorhomes are usually the same types offered in full-size semi-trucks.

Class A diesel pusher RV engine
Know the type of engine your RV has before you hit the road.

Pro Tip: We compared the pros and cons of a Diesel Pusher vs. Gas Motorhome. Find out which is better!

Is It Better to Have a Gas or Diesel RV?

There is no pat answer to the question of “Which engine is better, a gas or a diesel one?” We can tell you the differences between the two. However, you will have to look at the advantages of both to decide which fits your specific needs more closely.

A diesel engine usually will provide better fuel efficiency because it has higher energy density and will get up to 30% better fuel economy than a comparable gasoline engine. Still, the cost of diesel fuel is frequently more expensive.

diesel RV Fill
Filling up our RV can frequently cost $700!! Ahh

Diesel engines will normally last almost twice as long as their gas counterparts, but they are more expensive to maintain due to their size and oil capacities. And diesel-run recreational vehicles are much more expensive to purchase, as well. This also suggests that the resale value of a well-maintained diesel rig will be higher. 

Most diesel motorhomes also have air suspension and air brakes. This can significantly improve ride and stopping power but is one of the reasons for the price difference.

A diesel-fueled RV has more torque than a gas-powered one. That means there’s more power on uphills, and the rigs can tow more weight. And finally, any diesel engine built after 2010 requires the use of a diesel exhaust fluid called DEF, adding cost and upkeep to purchasing an RV with a diesel engine.

Pro Tip: Learn about the potential problems with DEF heads before you purchase a diesel engine coach.

Class A and B motorhomes at gas station
You’ll want to factor in MPG and fuel prices when comparing RV engines.

A gasoline engine requires fuel that is less expensive to purchase and cheaper to maintain. It may not last as long as a diesel engine, but in reality, most coach systems won’t live as long as a diesel either. The gas engine requires less costly maintenance, although it might be more frequent than a diesel counterpart. 

And overall, a gas-powered RV is less expensive to purchase from the onset, although its resale value will also be lower. Most large gas engines have enough torque to power up hills, but their tow value is usually less than a comparable-sized diesel vehicle. And gas engines don’t require any exhaust additives to operate properly.

Overall gas coaches tend to be more economical overall at the expense of some luxuries.

What Is the Best Gas Engine RV?

A V10 ford triton engine was once king in the Class A motorhome division, as it could push the added weight of a large coach. But gas mileage was very low, so now more large gas-powered RVs are using a V8 engine, especially in the Class C.

In the Class B camper van lineup, Ford has challenged the diesel market with an EcoBoost V6 engine that gets 20 miles per gallon and can tow up to 3,500 pounds.

The new 7.3 ford V8 is replacing the V10 in many uses and is expected to be one of the go-to choices for a fuel-efficient (relative to past engines) option.

What Is the Best Diesel Engine for a Motorhome? 

Most of the larger class A diesel motorhome engines tend to be very reliable as long as they are maintained because of the limited use of an RV compared to their lifespan potential. There have been specific problems over the years with particular engines so do your research, but most of them tend to be very reliable. The Cummins ISX is by far one of the most common engines and known for extensive reliability in RV’s.

Cummins diesel RV engine
You’ll often find a Cummins X15 in large Class A motorhomes.

On the smaller side, Mercedes produces an excellent diesel engine for Class B and Class C RVs. Their 4-cylinder option has 161 horsepower with 265 foot-pounds of torque, and the six-cylinder option has 188 horsepower with 325 foot-pounds of torque. These engines are highly reliable and offered excellent fuel efficiencies.

Pro Tip: Get the inside scoop on a Motor vs Engine: Is There a Difference?

Common Engine Problems in RVs

Since RV engines are built for the long haul, most of the problems encountered have more to do with lack of use. Running an engine regularly keeps its internal parts lubricated and free of moisture that can cause corrosion. Fuels and oils also break down when not used or refreshed and can cause many issues. Even plastic and rubber parts like bushings tend to do better with use because it keeps the oils in them from drying out. Long-term RV storage without running a rig can cause all kinds of problems.

Diesel RVs also don’t like too much cold weather and don’t perform at their best in high altitudes. And both engine types need to be exercised, even when not in use. Engine belts can get old and crack, requiring replacement, and you must check oil and coolant levels weekly.

In summary, the most common RV engine problems are not with parts worn out, but parts not getting used. Dead batteries are probably the most common and simple engine problem. Rodents getting into idle engines and making nests are sadly one of the most common causes of engine damage. This can be prevented with proper storage and running the engine at a minimum of once a month.

Pro Tip: Don’t go too long without checking your oil if you want to maintain the health of your engine. Discover How Often Should I Really Check My Oil?

Class A RV at repair shop
Frequent checks and maintenance are key to preventing costly repair shop visits.

How to Properly Store an RV Engine

Use Fuel Stabilizers 

Putting some fuel stabilizer into the gas tank on diesel and gasoline-powered vehicles will prevent the fuel from getting stale, preventing sediment formation and corrosion. Add it just before placing the RV in storage.

STA-BIL Storage Fuel Stabilizer - Keeps Fuel Fresh...
  • Preserves Fuel - Keeps fuel fresh for up to 24 months so you can...
  • Prevents Corrosion - Maintains a healthy fuel system by ensuring...
  • Ensures Quick, Easy Starts - Helps you store any equipment or...

Run Every Month Until Warm

Be sure to fire up the engine every month or so, letting it warm up. It is also an excellent time to exercise the vehicle’s generator, as well. Warming up the engine will drive out moisture, run off rodents, lubricate parts, and keep rubber at its best.

Disconnect Batteries  

Don’t forget to disconnect the chassis and coach batteries when putting your vehicle in storage. Even if you are not using any of the systems, there is still a drain on the battery that will render it useless when you take it out of storage.

How Important Is the RV Engine Choice?

Your RV engine choice is a personal decision. It’s based on how you’ll drive, purchase cost, maintenance and fuel costs, and engine power. Narrow down your choices first by deciding what size and type of RV you desire, then test drive a diesel and a gasoline-powered version.

For example, we personally have a coach powered by a Detroit Diesel Series 60 14-liter engine. This is one of the largest engines put in a coach and we chose it because it’s our home, and we wanted the power to carry tons of weight. It has been a great choice for us, but I sure as heck wouldn’t recommend it for the weekend user or less, as maintenance and costs are very high.

Uh oh: Our engine blew a head gasket. Here is why and how we fixed it.

detroit diesel RV
With 65,000 LBS gross, we need a BIG Engine

Use our guide to consider the pros and cons of each engine type, and you will likely land on the RV engine that is best for your needs.

What’s your RV engine preference? Drop a comment below!

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About Tom and Caitlin Morton

Tom & Caitlin Morton of Mortons on the Move gave up the stationary life for one where they are constantly on the move. They are full-time travelers, television hosts, and digital media producers.
They left their jobs, sold their house and possessions, and hit the road in September 2015 in their full-time “home on wheels”. Since then they have traveled the US, Canada, and even internationally by RV.
Now, they are Discovery Channel & PBS TV Co-stars of “Go North” on Amazon Prime Video, co-founders and instructors of RV Masterclass, and contributing authors for and an Arizona travel guide.

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James alexander

Tuesday 15th of August 2023

What did they put 454s in