Inspecting the Engine
Is the Idle high, low, or fluctuating?
You will want to be aware what is considered the normal idle speed of the RV that you are interested in purchasing.
Run it for a while to determine if it runs within the normal ranges both at the initial start of the vehicle and after 10 to 20 minutes.
Some engine idling issues do not show up until after they have warmed up from use.
Diesel High Idle Toggle
Diesel engines also have a high idle option that you will want to test as well.
At a minimum, the idle should reach 1,000 RPMs when the switch is toggled to the active position.
This is a protective feature that prevents wear and tear in the cylinders. Diesel engines can damage themselves if they are parked in one place for too long while running.
The fuel that is injected into the cylinders requires a minimum temperature to be fully utilized.
That temperature is not reached while it is stationary, and that unburned fuel can remove the oil that is greasing the inner walls of the cylinder.
Without it, the metal of the piston and the metal of the cylinder wall will sand each other down.
Check for Engine Leaks
A leaky engine can indicate a small issue that can be fixed with the replacement or refastening of a tube.
It could also indicate a crack in the gasket which might require an engine replacement or some other serious issue that will cost you more than a pretty penny.
One of the simplest checks is to look at the ground underneath the engine.
Thanks to gravity, almost all oil leaks leave evidence on the pavement. Don’t assume that the potential puddle on the ground is oil.
There are many fluid at play here, so take some time to identify what you are looking at.
There is a potential rainbow of colors, and each of them can indicate a different issue.
Fluid Color Guide for RVs
*Note – The following color guide is for the typical colors of the various liquids. Some manufacturers make their liquids with colors not exclusive to the ones described here.*
That’s probably just water, so you probably don’t have a problem.
When your engine is running correctly, hydrocarbon fuel is introduced into the cylinders, oxygen is pulled into the same chamber, and the piston compresses the mixture before adding a spark to create an explosion.
Just two hydrocarbon molecules and the present oxygen have enough hydrogen and oxygen molecules to produce 18 water molecules (H2O).
This means that after all the molecules have finished their explosive mingling, there will be a byproduct of water.
Pink fluid will either be a power steering fluid leak or a transmission fluid leak.
If it is from the power steering, then it is likely leaking from one of four places; the pump, hoses, cooler, or rack.
If it is a transmission leak, it probably won’t cause any major issues in the short term, but that will need to be repaired.
A leaky transmission has an expiration date if left unfixed, so you will want to make sure that the transmission isn’t on the brink of failure.
Transmission leaks can be from small bits of damage from rocks and other objects that get tossed into the undercarriage of the vehicle.
It might be from a punctured pan, a cracked line, or a loose seal.
Typically, it will be a cheap fix.
Transmission fluid sometimes comes in red.
Rather than restating the information, read about the transmission fluid located in the “Pink” description.
This will likely be from one of two things.
First, transmission fluid can change color over time, so that fresh red or pink fluid that you bought will eventually take on a whole new hue of orange…or close enough to it to trick the eye.
If it isn’t that, then it is presumably going to be antifreeze.
It is even more likely if you are located on a coastal region.
The salty air of the ocean can rust untreated metal and that rust can mingle with the antifreeze.
This is rather ironic since one of the primary functions of antifreeze is to prevent rust.
Leaky antifreeze can indicate some rather serious potential issues.
You might have a blown head gasket which can mean that the engine is in for a costly fix.
Not all hope is lost though because it might be something simple such as a leaky radiator hose.
You never know until you inspect.
Coolant can sometimes come in yellow.
You can find the leaks in all the typical locations of hoses, lose fittings, or a damaged coolant reservoir.
Antifreeze – Please refer to the “Orange” description for more information.
Windshield wiper fluid, not a big issue.
Still, you’ll want it fixed before the bugs begin to block your view outside your cabin.
Dark Brown Liquid
Question – What’s more important than making your RV move? Answer – Making it stop.
Thankfully, I’ve never had this problem.
Brake fluid and old motor oil have a similar appearance, so take the time to figure out what it is if you find a puddle of dark brown liquid.
If it is a brake fluid leak, then it shouldn’t be too expensive to repair.
If it is a motor oil leak, then there is a very wide range of potential costs.
It might be a loose fitting, or it could be a crack in the head gasket.
Light Brown Liquid
It could be motor oil, or it could be gear oil for a manual transmission.
We already went over motor oil in the “Dark Brown” section, so let’s skip over to the possibility of a gear oil leak.
Manual Transmissions are lubricated with gear oil, and if the oil is low from a leak than it can destroy the transmission.
It might rip out the teeth from your gears, destroy your ball bearings, or ruin the driveshaft.
If there is a leak, it is probably going to be located in a seal or a gasket.
RV Smoke Colors
Smoke can tell you a lot about the state of your engine.
There are three main types of smoke that you will see.
Here is what each one probably means:
This could be a pretty big problem.
When you see blue smoke that typically means that oil is leaking into the cylinders and mixing with the fuel and air mixture.
Sometimes, there will be a easy fix such as replacing a seal or two.
However, sometimes, this can also be an indication of something as big as a broken head gasket.
If I came across blue smoke, I either wouldn’t buy the RV or I would hire someone more qualified to take a look at the RV before I would even consider buying it.
This might not be an issue at all. Some vehicles emit black smoke when they first start up, and gradually clear up after they run for a few minutes.
There is a standard operating temperature for all vehicles, and it can take a little bit for vehicles to warm up to that…especially if you live in a colder climate.
If it isn’t the operating temperature, it will probably be a decently cheap fix.
Black smoke can be caused by incomplete combustion, probably due to air flow issues or your spark plugs.
Check the air filter to see if that is clogged up.
Also, check the spark plugs. If you noticed any issues when you checked the idle of the RV earlier, it may be caused by a bad or dying spark plug or two.
The fuel regulator may have gone bad.
The amount of fuel and oxygen has an ideal ratio of molecules that react to each other in an explosive way when there is a lot of pressure and a spark.
If that ratio is off, then some of those hydrocarbon molecules will not be able to react to the oxygen molecules, and there will be wasted fuel expelled from the exhaust pipe in the form of black smoke.
While this is unlikely to be very damaging to your engine, your gas mileage might take a hit.
This could be simple vapor, but it could also be a death sentence to the engine.
If it is water vapor, then the “smoke” should dissipate rather quickly.
Also, as the car warms up that smokey trail should begin to disappear almost entirely.
If it doesn’t than you might have a much more serious situation on your hands.
If the it isn’t a prime example of condensation, then it might be a prime example of one of three unfortunate issues:
Cracked Engine Block or Damaged Cylinder Head
If you come across either of these issues they usually mean replacing the engine. Mosey onto the next RV if you come across them.
Broken Head Gasket
Nestled right between your cylinder head and the engine block – The head gasket is designed to seal the cylinder, so that your pistons can build up pressure to create the biggest explosion possible to propel your RV forward.
When subjected to such massive forces so many times a second, wear is bound to happen.
Eventually, given enough time, the head gasket is bound to blow.
Check the Belts
Are the belts loose? Are they damaged or worn down? Has any oil or coolant dripped onto the belt.
When I got my first car, I had a coolant leak that dripped onto my timing belt.
I didn’t think that it was a big deal. Sure, the cost to repair the reservoir was a bit of a pain, but that kind of thing happens.
What I did find frustrating was a snapped timing belt that happened about a week or two after getting the car back from the shop.
I got off easy since the timing belt didn’t destroy the engine when it broke.
A lot of people can receive quite the repair bill if that timing belt makes a destructive exit.
I found out later that the coolant had leaked onto the belt and dramatically increased how fast it was worn down.
If the belts are loose, you might hear a noise of the belts slapping or knocking against the rest of the engine.
Provided that the belt doesn’t break beforehand, it will eventually stretch out to the point of becoming loose.
This can trigger the check engine light, and if you have a code reader for the engine it will probably be classified as “valve timing.” The readers are inexpensive, so you might want to check into that.
Check Everything Electrical (Engine, Inside the RV, the Fuse Boxes, and everything at the helm)
Check the Wiring, the outlets, flip all the switches, and the look at the Fuse Box
Like any house, or car for that matter, RV’s are prone to shorts.
Check every outlet to make sure power is running through correctly.
You can buy Electric Socket Testers on Amazon for 10 bucks, so it is pretty affordable. Of course, you could also just bring in any appliance that you happen to own.
If the toaster toasts, then the electricity is flowing.
Wiring is insulated, but sometimes that insulation is damaged. This will often be rather visible as the insulation is quickly burned from the electricity that flows through the wires.
Because a lot of these wires are bundled together, one damaged wire usually means multiple damaged wires.
This isn’t too hard to fix if you can locate and reach them.
Sometimes, wildlife that surrounds your property can chew through wires.
Some animals have teeth that grow in a similar manner to human nails. These teeth have to be kept in check and shaped through the act of chewing.
That is why these frustrating animals will chew through the wood of your house, or in this case the wires of your RV.
If this is a problem you are dealing with read our post on mouse proofing your camper.
After checking the outlets and wires, start flipping switches, turning knobs, and activating every single electronic that you see.
Check the heater, air conditioner, tv, radio, gauges, lights, camera, GPS, CB radio, seat warmers, cruise control, horn, all of the fans, and the fridge.
Make a list, and check off each one.
Listen to the Engine
There are a thousand things that can go wrong with an engine, and most of them will tell about the issue of you listen to it.
Start the engine – Are there any knocks, slaps, whines, squeals, etc.
Regarding Diesel Engines
Diesel Engines will have a knocking noise even if everything is running smoothly.
This can make it more difficult to diagnose if something is going wrong, but you should still take the time to see if the engine has any issues.
Check the Fuse Boxes
Most vehicles have two fuse boxes, and you will want to check both of them.
One of the easiest ways to find an indication of an electrical problem is to take a glance at the fuse boxes.
Look at each one, and look for burn marks from overloaded / broken fuses. If any of them are burnt, or if any of them look brand new, you might be dealing with a short in the electrical system.
Look for Signs of Owner Neglect
People telegraph their behaviors, and it is very difficult for them to hide the evidence.
Look for patterns that indicate how well the seller was likely to take care of the RV.
How clean is everything? How low are the fluids? Are the tires deflated?
Was the vehicle left to the mercy of the elements?
How many tiny repairs were determined as not worth the time of the owner? I’m sure that you get the point.
The invention of slides was fantastic for those living the RV lifestyle.
It answered the problem of too little room pretty well. Of course, introducing new parts to a system means that more things can go wrong.
Knowing this, there are a few things that you will want to check when looking at the slides
Slides have a motor that extends and retracts them.
That motor is placed under a decent amount of strain, and sometimes it will break down.
Listen for any errant grinding or popping noises, watch the slides and compare the speed of the transition to see if any of them are moving slowly, is the motor sticky or making stuttering movements.
Pay attention. You’ll probably have a decent idea if something is going wrong.
Check for how flush the slide outs line up against the rest of the cabin in both their extended and retracted state.
This is the issue that all trailers are notorious for having.
If you know someone with a trailer – Ask your friendly neighborhood RV owner if they have had to deal with water damage, and almost every time the answer will be “yes.”
Let’s start with the outside.
Check the seams around the windows, doors, and especially around the slide outs for malformations caused by water penetration or old age.
The slide out have two separate seems. One seem is for the retracted state and one is for the extended state.
These could wear out faster than the rest of the seems due to the constant movement and stress from the slides.
The seams may feel soft or too brittle. Feel along all the seams and you will quickly begin to know what is normal and what is not, so you shouldn’t have too much difficulty noticing the odd spots.
Water Damage – Check all the Baseboards and Floors
Areas around the bottom of the walls are usually the first to be damaged from a water leak. Usually, that is most evident by a discoloration that won’t be too hard to spot.
Water Damage – Delamination
Water damage can cause layers in the walls and floors of the RV to separate which can manifest through a bubbling of various surfaces.
You can check for this by standing on the outside of your rv and lining your eyes up to front or the back of the exterior wall of the RV.
When looking from front to back or back to front, you should notice any protrusions if there is any water damage.
After visually checking, run the palm of a hand along the surface. Are there any uneven and protruding surfaces?
If yes, then you probably have water damage.
Like anything that is battered by the elements, awning can be worn down over time and will eventually need to be replaced.
Check it’s condition; it should be relatively straight forward.
You need a stable surface. Is everything level?
If the landing gear is powered, are there any noticeable straining noises? Is the extending motion smooth, or does the motor need to be replaced?
Is the battery powerful enough to handle the landing feet?
Propane Tank Connections
This doesn’t require much explanation, but I do have a tip.
Mix up some soap and water and apply it to the tubes, valves, and connections.
If there is propane in the tank, a leak should become evident if the propane tank starts to blow bubbles.
There are more potential issues than I can even begin to list.
That’s what you get you combine something as complicated as a house with something that moves at 80 miles per hour.
Honestly, what are we thinking…I hope I haven’t scared you away from pursuing an RV purchase.
Sure, it may have its risks, and it will definitely have a fair amount of upkeep.
It is worth it if you love the lifestyle.
There is a freedom in the ownership, and you will have the opportunities that a fixed home just cannot even begin to offer.
Just remember…please remember. Have it inspected, or learn to inspect it yourself. This is a home.
It is not a new phone or a new laptop. Give it the consideration that it deserves, and you will be much more unlikely to regret the purchase.
I am a well traveled Marine Corps veteran that enjoys the outdoor and nomadic lifestyle that RV living provides. I am also a member of the National RV Inspectors Association (NRVIA.org). As the founder of Camperguide.org my goal is to provide you with well researched information so that you can enjoy the best of the RV lifestyle.