One of the most common, if not THE most common, problem associated with trailer towing is engine overheating.
With factory installed trailer towing packages, a heavy duty cooling system is usually included. Heavy duty cooling systems are available as optional equipment on most cars, with or without a trailer package. If you have one of these extra-capacity systems, you shouldn't have any overheating problems.
If you have a standard cooling system, without an expansion tank, you'll definitely need to get an aftermarket expansion tank kit, preferably one with at least a 2 quart capacity. These kits are easily installed on the radiator's overflow hose, and come with a pressure cap designed for expansion tanks.
Another helpful accessory is a Flex Fan. These large diameter fans are designed to provide more airflow at low speeds, with blades that have deeply cupped surfaces. The blades then flex, or flatten out, at high speeds, when less cooling air is needed. These fans are far lighter in weight than stock fans, requiring less horsepower to drive them. Also, they are far quieter than stock fans.
If you do decide to replace your stock fan with a flex fan, note that if your car has a fan clutch, a spacer between the flex fan and water pump hub will be needed.
Aftermarket engine oil coolers are helpful for prolonging engine oil life and reducing overall engine temperatures. Both of these factors increase engine life.
While not absolutely necessary in towing Class I and some Class II trailers, they are recommended for heavier Class II and all Class III towing.
Engine oil cooler systems consist of an adapter, screwed on in place of the oil filter, a remote filter mounting and a multi-tube, finned heat exchanger, which is mounted in front of the radiator or air conditioning condenser.
An automatic transmission is recommended for trailer towing. Modern automatics have proven reliable and, of course, easy to operate, in trailer towing.
The increased load of a trailer, however, causes an increase in the temperature of the automatic transmission fluid. Heat is the worst enemy of an automatic transmission. As the temperature of the fluid increases, the life of the fluid decreases.
It is essential, therefore, that you install an automatic transmission cooler.
The cooler, which consists of a multi-tube, finned heat exchanger, is usually installed in front of the radiator or air conditioning condenser, and hooked inline with the transmission cooler tank inlet line. Follow the cooler manufacturer's installation instructions.
Select a cooler of at least adequate capacity, based upon the combined gross weights of the car and trailer.
Cooler manufacturers recommend that you use an aftermarket cooler in addition to, and not instead of, the present cooling tank in your car radiator. If you do want to use it in place of the radiator cooling tank, get a cooler at least two sizes larger than normally necessary.
A transmission cooler can sometimes cause slow or harsh shifting in the transmission during cold weather, until the fluid has a chance to warm up to normal operating temperature. Some coolers can be purchased with, or retrofitted with, a temperature bypass valve, which allows fluid to flow through the cooler only upon reaching normal operating temperature.