Is The 8.3 Cummins a Good Engine? (Review, Oil Capacity, HPs)
The thing about motors is that when under heavy loads and lots of stress they tend to break down. Advancing technology has given motor makers advanced tools to overcome those problems and keep their motors on the road. Cummins takes full advantage of those advanced tools to make great engines.
Is the 8.3 Cummins a good engine? The 8.3 Cummins engine has a great reputation and is powerful enough to move fire trucks, dump trucks, and similar heavy rigs. Its 400 HP and 1075 torque made it the perfect engine to use in those larger RVs.
To learn more about the 8.3 Cummins diesel engine, just continue to read our article. It has the information you need to know about so you can feel good about what is powering your RV. Take a few minutes and get caught up to speed on this powerful motor.
Cummins 8.3 Engine 101
Is The 8.3 Cummins a Good Engine?
From all reports, the 8.3 is a good engine. Not only does it have the power but it also has the lifespan. This motor should be able to last you a long time without any major repairs being done.
While we reported the engine providing 400 HGP at 1075 ft. lb. of torque, this engine has several levels of horsepower depending on the rig and rpm. Some reports have the hp down to 279 while others have said the engine produces 300. Your results will depend on the model and other factors.
We have heard that the CAPS pump was the greatest weakness on this motor and the destruction of the throttle TV cable linkage was next. There are a few design problems but Cummins has built a great engine in the 8.3.
There are few negative comments about this motor as some of their engines have reached 7 figures in mileage and still going strong. They may outlast the vehicles they were placed in.
However, this motor does not do as well when it is placed in agricultural machinery. It likes the road better than dirt.
Cummins 8.3 Reviews
The reviews we saw all spoke highly of this engine for the most part. While nothing is perfect in this world, the 8.3 comes close in many people’s minds. We just mentioned a couple of the flaws that have been found on this motor but we do not see many complaints at all.
One reviewer said this motor has the power to move heavy vehicles but it is not great at being fast. Other diesel engines seem to be able to go faster than this model. Another reviewer praised the engine for its ability to be flexible. It is not that hard to add more power and increase the HP when you need it. Some people provide a more honest review of the motor and have highlighted the major problems that can arise with this motor.
Usually, those problems do not show up until the engine gets a little older. They also pointed out that the CAPS pump system was not as good as the original P Pump system.
How Much Horsepower Does An 8.3 Cummins Have?
It has been reported that the 8.3 is capable of producing up to 400 HP. Others have talked about how they only get 300 HP but if you slide the plate forward on the P pump system, you can get about 30 HP out of the motor.
This motor is more at home in RVs as they are said to outlast the RV and not have any major work done to them. That kind of power makes sure your rig gets over steep inclines even when you are towing a little extra weight.
There is a lot of talk about how reliable this motor is, so you can be sure that the horsepower you get will be enough when you want to take a nice RV vacation.
How Much Does a Cummins 8.3 Weight?
This motor is not for small vehicles. It would double the weight of some and increase the overall weight of others by 1/3 to 1/2. Its total weight without fluids, etc., is 1,630 pounds.
When you add the fluids you are increasing that weight by quite a lot. This amount of weight is nothing too big rigs like fire trucks, garbage trucks, and similar vehicles but placed in rigs smaller than a Class A RV is not going to be a good idea.
With that said, there are other versions of this motor which may be a little bit lighter but do not count on big reductions. The 8.3 is part of the C-series of motors Cummins produced so there may be a few models a little bit lighter than this one.
The oil capacity of the 8.3 is just over 6 gallons which will add some weight to the engine when it is placed into your vehicle.
Cummins 8.3 Dimensions
The 8.3 is an inline 6 and it is measured at 509.5 cubic inches in size. The approx length, width, and height of the motor are as follows: overall length 56 inches, block length 34 inches, overall width is 38.5 inches and overall height is 39 inches.
Those measurements may change depending on the year the motor was built and what its purpose was. There are marine 8.3 Cummin motors as well as vehicle 8.3 engines. There may be a bit of discrepancy in the size of both engines.
Also, we reported the engine to weigh only 1,630 pounds, some versions come in 300 pounds or heavier. Some of the versions clock in at almost 2000 pounds which may make those lighter engines a tad bit smaller than the one we gave the dimensions.
Check with your local Cummins dealer to get accurate figures on its dimension. That way you can measure your current rig correctly and see if the motor will fit inside your rig.
Cummins 8.3 Oil Capacity
Like the weight, the actual oil capacity may come as a bit of a shock. Many people are used to the smaller car and pick-up truck capacities and are not surprised to hear amounts like 7 quarts, 5 quarts, or even 4 quarts.
However, we are talking about a big motor here and it needs approx. 6 gallons of oil to run properly. One source reported that the actual figure for the amount of oil this e4ngine required is 23.7 quarts.
Either way, you will need a lot of oil to make sure all the parts of the 8.3 are lubricated. What has been said as the biggest engineering feat this company is that Cummins has been to figure out how to overlubricate the motor and reduce the possibility of thrown rods or spun bearings.
The oil filter should be changed every 15,000 miles or 500 hours, the fuel filter has the same requirement while valve adjustment should take place every 150,000 miles or 5,000 hours.
What Oil for a 8.3 Cummins
People have their favorite brands that have given them lots of success and good performance over the years. However, Cummins recommends that you use products that meet their standards in the 8.3.
There are a lot of good brands out there that should meet those high standards so you do have some leeway in which one you use. Some people use Rotella 15W40 while others Castro or Della brands.
They use these different brands more out of economic reasons than one being superior to the other. One owner of the 8.3 says that he did not see much of a difference between the brands when it comes to oil.
They also change the oil every 5,000 miles or once a year. Cummins recommends every 6 months but that frequency would depend on how often you drive the vehicle with the 8.3. Della 15W40 is good as is Valvoline Premium Blue. If you are in doubt, check your manual and then find the brand that meets the specs in its contents.
Cummins 8.3 Torque Rating
This section could get very technical and boring if you are not someone who is really interested in engines and their essential details. Torque is not usually what is thought of by RV owners who just want a good engine that will last and not give them a lot of problems.
The torque rating for the 8.3 ranges between 670 to 1075 ft. lb. In that range, you should get varying degrees of horsepower. However, torque is not always used to describe power. It is also used by how tight you should tighten those bolts.
Here is a chart to help you get the right torque on those bolts if you like to work on your own engines. Then there is this torque chart to help you find the right power level when you need more horsepower.
The 8.3 is often listed as an ISC motor and is not mentioned specifically in that category on that chart. There is a 6CTA8.3 mentioned twice but it may not be the same motor.
Cummins 8.3 In a Pickup
Some people have floated the idea of putting this motor in a pickup truck but that idea was shot down. The reason it was discouraged was that the motor is too tall to fit in the engine compartment of a pickup truck.
Cummins does make diesel motors for pick-up trucks and they are very reliable, durable, and very powerful. However, those motors are the 6.7L Turbo diesel or one model of the 5.0 turbo diesel.
The Cummins website does not mention the 8.3 as a fine fit for a pickup truck, although there is a remanufactured turbo diesel you can buy to be put in your new pick-up.
There may be some confusion as the 8.3 is also called the 6CT and the ISC but the dimensions are not changing that much as those labels all refer to the same motor. If they are small enough to fit in your pick up they will have the Cummins power, etc., included and your pick up should be able to tow and haul a lot of weight.
The 6CT or ISC will work in medium trucks but pickups may not qualify for that category.
Cummins 8.3 vs 8.9
The 8.9 is supposed to be based on the 8.3 C-Series motor but it is a more powerful motor than the 8.3. Both engines perform well though the 8.3 is a lighter motor and takes a little weight off the rig.
The power in the 8.9 is the biggest difference. With the 8.3 you may find it a little difficult to keep the speed up while the 8.9 doesn't lose any speed as you travel along the major highways.
Another difference is that the 8.3 will get better gas mileage than the 8.9. If you prefer power and speed over economy, then the 8.9 is for you. The latter engine has about 20% more torque than the 8.3 but the trouble there is that some transmissions cannot handle the 1200+ torque produced by the 8.9.
Which one is better depends on which factors are important to you. Some will take the 8.3 over the 8.9 based simply on mpg stats alone.
Cummins 8.3 vs 5.9
The 5.9 is a smaller engine. What that means is that while it will have less weight and fit into a smaller chassis, it does not have the power of the 8.3. Plus, the design is a bit different as the 8.3 has a rounded front design and the 5.9 comes with a straight octagonal-shaped line to its design.
Then the 5.9 has individual cylinder head covers while the 8.3 has one. The injectors are on the same side as the cylinder heads in the 8.3 and the 5.9 has those injectors on the opposite side.
Which is better would be determined by the purpose. The 8.3 is on the heavier side of things so it is not a practical motor to place in many vehicles. The 5.9 should fit better in smaller ones and perform just as well.
Cummins 8.3 vs 6.7
The biggest difference will be seen in the fuel mileage. The heavier the load the more fuel the 6.9 will use up. The 8.3 likes heavy loads and does not use as much fuel when loaded.
Then the 8.3 will have a higher torque making it the better engine for towing trailers, toys, and so on. The power in the 8.3 makes it work easier when loaded while the 6.9 will be stressed and overworked carrying the same weight.
When there is no weight on the 6.7, then it will perform better than the 8.3 and you have to gauge your purpose to see which motor will work for you. Overall, the Cummins 8.3 is the better engine here even if you prefer the 6.7.
It just can perform better and should last longer because of the ability to move heavier weight.
Cummins 8.3 Problems
The following problems may appear more often in heavy-duty trucks and equipment than they will in most motorhome applications. The first problem will be the block.
It is said that you may lose a piece of it at about 6,000 to 8,000 hours but in heavy-duty vehicles pulling a lot of weight. This is not a common occurrence in motor homes.
Then the engine can drop a valve or two when constantly working with heavy-duty vehicles. RVs do not experience this issue unless you got a bad motor. Then the biggest issue for RV owners may be the CAPS pump system. It seems that this system is inferior to the original P pump system.
Many 8.3 owners have reported having trouble with this upgrade. The source of this problem is an excess of water in the fuel. Another source will be too much heat. Deserts and the 8.3 do not seem to get along very well.
When the engines age, you may see more minor issues with the motor that will need your attention. But that is normal when it comes to motors and mechanical things.
8.3 Cummins Hard to Start
This motor can be hard to start at times. It seems that it also does not like the cold weather and you may have trouble getting the parts to kick over and get moving. But there are other sources for the problem.
One is that the two windings in the solenoid may have shorted together causing the engine to fail to turn over. Another problem that may cause the engine to be slow to start is that something may be sticking inside after sitting for long periods.
A little lubricant should take care of that issue. Then there is the fact that the fuel line may have gotten some pinholes in it and you are losing prime as you try to start the engine.
Replacing the fuel line with a new one should solve that problem for you.
How to Prime an 8.3 Cummins
Priming is important on the 8.3. When the fuel pressure is normalized it helps reduce wear and tear on the starter. Here are the steps to get the engine primed.
#1. put the truck or RV on level ground and make sure you have enough fuel in the tank.
#2. Locate the lift pump and push the button (earlier pre-1998 models) on it to get rid of any air in the system. Bump the starter and have the key in the on position and allow the lift pump to cycle (post-1998 models).
The cycle should take about 30 seconds to complete and refill the fuel canister as well as prime the fuel system. You should do this 3 or 4 times to make sure the air is purged out of the lines.
8.3 Cummins Cam Sensor Location
The cam sensor location seems to be at the front of the engine about halfway down from the top. According to the diagram it is placed underneath the fuel filter and the fuel rail pressure system.
To find it may take a diagram to see its exact location as words sometimes are not enough. Besides a picture is worth 1000 words. At this link you will find several pages of diagrams and parts locations.
The trouble is you have to scroll down to about page 12 to find the right diagram to look at. The correct diagram is on the same page as another diagram displaying only 7 parts and their locations.
How to Get More Power Out of a 8.3 Cummins
The best way to add more power to the 8.3 is to find out which pump system is on the engine. If it is the original P pump then you are in luck. All you have to do is lift up the pump and move the plate forward.
By moving the plate forward we mean that you move it towards the front of the rig, not to the passenger direction. If the plate is already in that position then you can’t use this method to add more power. You are at your maximum level for this maneuver.
Some techniques only add more fuel and do nothing to add more power to the engine. So those should be avoided at all costs.
Some Final Words
You really cannot go wrong with the 8.3 engine. In fact, you really can’t go wrong with a Cummins diesel motor. They are well-built machines that should last you longer than the RV will last you.
That is what you want in an engine as you can always do a motor swap and keep the 8.3 with you no matter which rig you drive. Within reason of course.
