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Pre-Trip Inspection Checklist for Converted School Bus Owners. 

 March 24, 2022

By  Chris

by Chris

March 24, 2022

Yellow school buses

There is nothing quite like a skoolie trip with friends and family. It is a unique and adventurous experience – just like taking your whole house with you while discovering different lands. 

However, just like any other vehicle, your converted school bus can break down on you, leaving you stranded in the middle of nowhere. Your skoolie costs can add up quick if you have to have it towed or allow a problem to get worse.

But don't worry, as we have put together a pre trip inspection you can follow before embarking on your school bus expedition.

The Engine

To begin with, open the engine compartment hood and see if it is properly mounted. Most tilt-forward hoods contain straps that secure the hood to the cowl. They also have a handhold formed in the center, right above the grille.

The correct way to do so is to use the front bumper as a step. Then, you can use your weight and your hand to pull the hood forward very slowly. Be extra careful since most of them are made of fiberglass, which is weaker than other materials.

If too much force is applied, the fiberglass can crack or break, costing you a lot of money and time. If your skoolie doesn't have the handhold equipment, you can raise the hood using its fenders close to the securement strap.
While this job is simple enough for one person, it is better to get someone else involved to help you out. After inspecting the engine compartment, close the hood very carefully. Make sure the hood is latched accurately on both sides.

Here are the engine accessories you need to check before closing the hood.

  • Generator
  • Alternator
  • Power steering pump
  • Air-conditioning compressor
  • Water pump

Now, check the engine oil level, usually between Full and Add. Also, check if there is any contamination from fluids or metal. If you have a diesel engine, the engine oil will be darker in color. However, if the oil is black, it is a sign it needs maintenance. Sometimes, the engine oil is milky in appearance. This happens for several reasons, such as

  • Weak head gasket
  • Cracked cylinder head or engine block

In some cases, the oil level is too high. It happens for two reasons. Either the coolant mixes with the engine oil or stays on the bottom while the engine oil stays on the top, thus appearing full. Next up, check the oil filter for any leaks or damages. You must remember that the engine oil lubricates and cools the engine's rotating assembly.

However, the coolant and the engine oil should never mix. Low coolant and engine oil can increase the temperature of the engine. Therefore, you must invest in an oil cooler.

Next up, check the coolant level. While doing so, you must check the recovery tank for cracks and leakages. For some buses, the overflow tank has a glass that helps verify the level and condition of the coolant. Your coolant should be greenish. However, it can turn brown or orange due to corrosion, while aged coolant turns purple or pink.

Inspect the radiator for leaks and damages. Also, check for any debris buildup, as it affects the airflow, causing overheating. Make sure the hoses and clamps are properly mounted. Similarly, check the alternator wiring and make sure it is properly mounted. Also, while you're at it, look for burning or melting within the alternator wiring.

Next up, check the hydraulic brake system. First of all, check the cylinder system. Most diesel-powered vehicles have a hydro-boost unit or a vacuum pump. The hydro-boost uses a power-steering pressure, thus minimizing the pedal effort, just like vacuum boosters in gasoline engines. In some cases, this system pushes the power steering fluid into the brake system, leaving it inoperative.

Lastly, check the turbocharger, exhausts, and pipes for proper mounting, leakages, and cracks. To spot leakages in these areas, look for dark carbon spots. The oil lubrication for the turbochargers comes from the engine. Also, check the water to air intercoolers for leakages and cracks.

Brakes, Rims, Breaks, Tires, Hubs, and Suspension

First, check the hydraulic hoses and steering gearboxes for mounting errors, leaks, and damages. Similarly, check the rag joint and steering shaft for deterioration and damage. You should also check the steering linkage for bends and cracks. Cotter pins should be properly mounted, and the joints should be tight. While some minimal errors are fine, you should consult a professional if the joints and cotter pins can wiggle freely.

Next up, we have the leaf springs and the coil springs, which should be checked for rust, cracks, and abnormal wear. The leaf springs should be in line with one another. If they are asymmetrical, they should be fixed right away.

Axle beams and pins keep the leaf springs perfectly aligned with one another. If there is a misalignment, it alludes to a chassis problem, which you should troubleshoot promptly. It usually happens due to a bent frame, a product of rough roads and big bumps.

Smaller cutaway skoolies have an independent front suspension. Bushings, upper control arms, and mounting bolts serve the same purpose as the spring to frame mounts. It would help if you inspected these things for corrosion, damage, bends, and dry rot.

If you notice cracks in the rubber or the control arms, it is a sign they are worn out and must be replaced as quickly as possible. Then, check the u/c shaped bolts on each side of the axle. They wrap around the axle beam and pass through a spring that secures the springs to the beam of the axle.

Also, check the ball joints and wheel bearings. To do this:

  1. Have the questionable side of the bus lifted.
  2. Hold the wheel top and rotate it.
  3. Rock it back and forth.
  4. Pay close attention to the hub center. If it starts to wobble, the wheel bearing is bad and must be replaced as quickly as possible.

On the flip side, if the wheel rocks top and bottom, it alludes to bad ball joints, which you must replace before heading out on tour in your skoolie.

Shocks-

When traveling in a skoolie, driving on an unusual road is inevitable. Some of these roads will be uneven. Therefore, it is in your best interest to check the shock absorbers. Check for leakages, damages, and cracks. The shock absorbers are filled with oil. As a result, spotting a leakage isn't a big deal.

Next comes the air brake chamber, which you should inspect for correct mounting and signs of wear and tear. Remember to check the dust cap. A worn dust cap allows water and dust to enter the chamber, thus damaging it. Therefore, check the clamp to make sure the dust cap is secure.

Drum brakes have slack adjusters, which you should check. Ensure the pins are in place and there isn't any bend in the slack adjusters.

The tugging on your slack adjuster shouldn't be more than an inch. In most air brake systems, disk brakes aren't too common. However, skoolies built before 2010 will have drum brakes.

Smaller cutaway models will have discs with hydraulic brakes towards the front, sometimes in all four corners. You should check brake drums and linings for contamination, damages, and cracks.

Tires-

Now, let's move to the tires, the most important vehicle component. Check the tires for uneven wearing and flat spots. These tires hold up to 80-120 psi, and therefore, you will need a higher pressure gauge to monitor the pressure of the tires.

Also, check for rocks and debris between the tread and the wheel assembly. The tread depth for front tires should be 4/32 inches, while that of the back tires should be 2/32 inches. Besides checking the wheel, check the valve stem for twisting, leaks, and damage. Also, make sure the pinion gear cover seals are properly mounted and secure.

Bus Pre Trip Inspection

After the tires and wheels, you must check the axle/hub seal for mounting, missing nuts, bolts, seals, and leakages signs. Also, make sure it has the proper oil level. Most steer axle hubs have a grommet used to check the oil level in the hub. As far as drive axles are concerned, they have pinion seals that you should check for leakages.

There is a plugin in the center of the drive axle that you should remove to check the oil level in the gear. However, checking the differential oil level isn't necessary until a leak occurs, and leaks are usually obvious. Furthermore, there are sight glasses in some hub systems to monitor the oil level, similar to the sight glass for coolant that we discussed above.

Next up, inspect the lug studs for stripped threads or shiny metal signs. Rims can also have some damage in areas surrounding the lug holes. This damage occurs as rust or shiny metal in areas where the rim wobbles. Also, check the frame for non-factory welds and cracks.

Pressure Warning Test for Air Brake System

Depress the clutch pedal to see whether or not the transmission is neutral. This process applies specifically to manual transmissions. Put your bus in N (neutral) or P (parking) for automatic transmission. Now check the supply air pressure gauges. The residual pressure should be around 125 psi.

Turn the engine off.

If the pressure is well within the satisfactory zone, push the hand valve knob and release the parking brake. The pressure will drop slightly. Monitor the pressure for 1 minute. The supply pressure gauge shouldn't drop beyond 2 psi.

Now you must depress the brake pedal while monitoring your supply gauge. The drop should be slight at around 3 psi, but only upon application. Monitor it for a minute for bleed down.

Moving on, pulse the brake pedal very gently, and keep an eye on the pressure. The pressure should drop with every pulse.  While different systems have different standards, a standard application alarm will sound when pressure drops to around 60 psi. Continue to pulse until pressure drops to around 25 psi.  

At 25 psi the emergency brake should engage.

Start the engine and monitor the gauge to ensure compressor builds back up to normal operating pressures.

Engine Start Testing

Once the engine is turned on, the oil pressure rises within 3-5 seconds. If it doesn't, turn the engine off and keep it off until the problem is detected. While oil pressure varies for different applications, it should remain within the 35-45 psi limit when idling.

While the engine is running, the voltage gauge should show a voltage between 13.4 and 13.8 volts. Anything less than that points towards a faulty alternator, drive belt, or generator. If the voltage is more than the prescribed limit, the voltage regulator needs replacement.

Check your lights-

It might seem obvious, but check your lights to ensure they work. Use a helper to help you check them.

  • Check that headlights are functional and clean. High beams work.

  • Check that side marker lights are functioning properly.

  • Make sure taillights work. Press the brakes down and verify that the brake lights illuminate.

  • Check that the turn signals work and that the hazard flashers work.

Some Driving Tips

If you have a diesel engine for the skoolie, you shouldn't go beyond 1500-1800 rpm. Maximum rpms on a diesel engine powered school bus is around 2400rpm. On the flip side, you shouldn't exceed the 3900 rpm mark if you have a gas engine. However, there are a few exceptions to this rule. Check your manual-

You should revisit the manual or reach out to a professional dealer for your specific engine type and the rpm level it is capable of reaching.

Sometimes you may experience some overheating with no place to pull over. What will you do then? To cool the engine down, you must turn the heaters wide open. It will allow you the time you need to drive to a safe place for help.

When Descending Steep Hills

It would be best to downshift the transmission to save the brakes when descending downhill and control speed on steep slopes. In the absence of a proper braking system, it becomes difficult to control the speed of your school bus, and the sad part is that you can even lose control, which can be dangerous.

If you have an engine brake, make sure not to use it in wet or slick weather conditions. It may result in a skid, and you might even lose control if you do. When going downhill on a steep slope, hydraulic brakes come in handy. However, if the brake components are overheated, they can boil the fluid.

There are two techniques you can deploy to prevent brake fades. However, you should monitor your rpm. The first technique is the snub-braking technique. In this scenario, you should increase your speed to the maximum rating of the hill. Then apply the brakes and reduce the speed by 5 mph. Release the pedal and repeat the process until you come down.

The next technique is the stab braking technique, aka the coast and burns technique. What happens is the brakes tend to jam hard for a few moments. They are then released right before the lockup. You get maximum braking capability in that instant, and it doesn't create any heat buildup.

Although it isn't recommended for most situations, the stab braking technique works. When moving downhill, if you smell something burning, it is a sign your brakes are overheating. It is best to stop the bus and stay there until the brakes cool down when that happens. Overheated brakes are prone to catching fire.

The Final Thoughts-

Skoolies are fascinating vehicles, but check the things mentioned above before you set out on a trip. It is better to have your skoolie inspected, or else it can leave you stranded in the middle of an unknown location, where it is difficult to find help.

The specs above are more or less guidelines. You should always use the specification numbers in your manual. Most will have a pre trip check list in the manual.

The best approach to performing a pre trip inspection is a methodical one. Print out an inspection checklist and start going down the list step by step. Mark each item off as you complete it. Don't skip around. We've heard it a million times, "I thought you checked it."

You have come to just the place if you want to know more about skoolies and Jeeps. We love sharing overlanding, modifications and metal fabrication projects with other skoolie and Jeep enthusiasts.

Are there other pre trip inspection items you look at that you think are worth adding to this inspection checklist? Let us know in the comments below. Thanks for reading and safe travels.

Cheers

About the author 

Chris

Average guy that likes to build things and teach others what I learn. Family comes first. Steel, Jeeps and off-roading are all fighting for second place.

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