Trailer Owner’s Manual

15 Maintenance

15.1 Engine

Towing a trailer up steep hills or over long distances at highway speeds cause the engine to work harder than usual. It is best to change the engine oil before a long trip, and maintain the severe duty service schedule for oil change replacement.

Likewise, the cooling system is stressed more than usual, and so the engine coolant should be tested and/or changed before a long trip. Likewise, the engine fan and fan clutch or motor should be checked for proper operation, and any old hoses or thermostat should be replaced to avoid problems during travel.

15.2 Transmission

Like the engine, the automatic transmission also works harder than usual while towing a trailer. Its fluid should be changed according to the severe duty maintenance schedule, and an additional transmission cooler should be added if the vehicle does not already have one.

A manual transmission does not heat up as much as an automatic while towing, but its fluid should still be changed according to the severe duty schedule. The clutch should be replaced if it is showing any signs of slipping, since it will be worn more than normal in order to start the trailer moving.

15.3 Brakes

Your tow vehicle’s braking system should be maintained even when not camping, but it can become especially important when a trailer is being pulled, especially if the trailer does not have brakes of its own. A camping trailer can add 50% or more to the weight which must be stopped, resulting in much longer stopping distances.

Brake pads, rotors, and drums are all important to maintain, but there are some other additional things to remember:

Brake fluid:

Brake fluid naturally absorbs moisture. This water in the brake system can boil during hard braking, resulting in “brake fade”. Have your vehicle’s brake lines flushed every few years.

Brake lines:

Brake lines carry the brake fluid to each brake. Metal lines can rust from the inside or the outside, and the flexible rubber lines at each wheel can crack or decay. Either problem can result in the sudden loss of braking power, often to two wheels at once. These brake lines should be inspected periodically, and replaced if there is any question of their integrity.

Parking brakes:

The parking brake can be especially important while traveling and camping. Many roads and campsites are nowhere near level, and the transmission alone should not be relied on to keep your vehicle stationary. Learn to set the parking brake whenever the engine is turned off. Test the brake for function, and replace old cables or brake hardware if necessary.

Brake hardware:

During routine maintenance, brake calipers and drum hardware should be lubricated as a standard procedure, but after enough years it will be time to consider all new brake drums, rotors, and pistons. Any sign of a leaking or sticking brake system should be addressed before leaving on a camping trip.

15.4 Suspension

The trailer places extra weight on the back end of the tow vehicle, and this weight also causes a lifting of weight away from the front end of the tow vehicle. Crosswinds and turns cause the trailer to tug sideways on the back end of the tow vehicle, and braking while turning can cause the trailer to want to push the back of the tow vehicle straight while the tow vehicle is trying to turn. All of these forces result in additional wear on the tow vehicle’s suspension and steering components. See Figure 21.

Any looseness in the steering or suspension system or worn out shock absorbers should be corrected before towing a trailer. The shock absorbers should be upgraded to heavy-duty shocks if possible, since they will be receiving a much heavier work out from the trailer tugging and bouncing on the hitch.

Figure 21: Extra Forces On The Vehicle While Towing


15.5 Tires

Correct tire air pressure is essential due to the increased stresses on the tires, both from the extra load which must be carried, and from the extended highway speeds and high summer temperatures. Consult the owner’s manuals for the tow vehicle and trailer to determine the recommended pressures for your tires. Some manuals instruct you to add extra air pressure while carrying heavy loads, and also add extra air pressure while traveling at highway speeds for extended periods of time. Be sure to take each of these factors into account when setting the tire pressures. Check and inflate the tires while they are cold, and check them on occasion during your travels.

Signs of damage in tires include bulges in the sides, irregular wear, punctures, or small cracks in the sides or between tread blocks. Any of these should be reason to consult a tire dealer for possible replacement.

15.6 Tow Hitch

The tow vehicle’s tow hitch is responsible for keeping the trailer connected to the tow vehicle, and if either the hitch or its attachment points have become severely corroded, failure could occur resulting in possible damage or injury. Inspect both the hitch and also the connection hardware which mounts the hitch to the tow vehicle. Replace anything which is questionable.

15.7 Axles
15.8 Hubs
15.9 Bearings
15.10 Brakes
15.11 Caulking
15.12 Exterior
15.13 Windows
15.14 Skylight Domes
15.15 Hitch
15.16 Lift Springs
15.17 Shock Cords
15.18 Sanitizing the Water System