One of the most common problems associated with trailer towing is engine overheating. Solving the problem may be as easy as just not using the air conditioning when climbing a hill. 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 probably need to get an aftermarket expansion tank kit, preferably one with at least a 2 quart capacity. These kits are usually fairly easy to install on the radiator's overflow hose, and come with a pressure cap designed for expansion tanks.
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.
The increased load of a trailer causes an increase in the temperature of the automatic transmission fluid. Heat is the worst enemy of an automatic transaxle. 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 compressor, and hooked in-line 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.