Engines and Overheating - Pre-departure Engine Check List
May 8 2009
Before you head out onto the open road, it is always a good idea to check, and recheck, that your motor home or tow vehicle is in top form. Here is a brief list of essential items to look over.
Radiator -Check coolant level and condition. The coolant should never look mucky.
Check the radiator fins are clean and in good condition. Too many damaged fins lead to overheating. Extra antifreeze (2 x 4 l jugs) should be carried along with some water.
Obstructions - winter fronts (remove) and bug screens (cleaned often)
Radiator cap - Check for signs of leaking. *NEVER OPEN A CAP ON A HOT RADIATOR*
Radiator and heater hoses - Check for softening, hardening, cracks or signs of leaking (Spare hoses are cheap and should be carried)
Fan belt(s) - condition and tension (Spare belts should also always be carried)
Windshield washer fluid level
Wiper blade condition
Tires - Check pressure and condition of tread (including spare)
Brake fluid level
Battery - Check water levels and cable connections
Engine oil level
Transmission - automatic transmission fluid level and condition (not burnt)
Power steering - Check fluid level
*Engine oil service is recommended before any long trip.
Overheating
Radiator Coolant, or anti-freeze, works in both heat and cold - ensuring that your engine doesn't freeze or over-heat. Coolant acts as both a cooling agent, corrosion inhibitor for the metal parts of the cooling system & radiator. It also provides lubrication for the water pump and hoses.
Over time and with exposure to the cold of winter and the heat of summer, the additives are weakened and its effectiveness can be decreased. If the coolant looses its anticorrosion ability it will allow the system to corrode internally. If corrosion exists it can be seen by removing the cap and inspected inside the radiator core ( may need to remove some coolant). Using a coolant tester, you can determine the level of cold weather protection ( -45 c is recommended). By removing some of the antifreeze and replacing it with 100% antifreeze you can improve the protection.
Check and service your vehicles cooling system every 50-60,000 km or every 3 years (for most vehicles, it varies upon manufacturer and gas or diesel). Have the cooling system flushed and refilled with a 50/50 mixture of antifreeze and water, never more than 60/40. Also, pressure test the cooling system including radiator cap to ensure they are in proper working order. The cap must hold pressure (15-20psi most systems) because pressure reduces the boiling point. Inspect belts and hoses with every engine oil service. If hoses and belts are more than about four years old, replace them (old ones can be kept for spares. Have the fan clutch tested if applicable.
Coolant
The most common formulation of antifreeze is green in color and uses ethylene glycol as a base with anti-corrosion additives . The ethylene glycol provides crucial anti-freezing characteristics and the additives deliver the anti-rust and anti-corrosion capabilities.
In 1995, most GM vehicles started coming from the factory with an extended-life antifreeze, trademarked as DEX-COOL®. Different in appearance, DEX-COOL®, and its aftermarket equivalents, is orange color. It still uses ethylene glycol as a base, but contains a different additive package than standard green antifreeze. This coolant is designed to protect cooling systems for up to 150,000 miles or five years.
Medium-duty and heavy-duty diesel vehicles should use specific coolant formulas, with additives that meet recommended practices of the American Trucking Association's Maintenance Council. Some OEMs use specific OAT (organic acid technology) formulations. Cummins forbids pure OATs, and recommends a specific silicate-containing hybrid with heavy-duty additives as part of it’s maintenance program.
Both Cummins with its hybrid coolant and Texaco with its heavy-duty OAT have supplementary additive packages to extend it‘s antifreeze. Cummins recommends installing an additive package (or a new coolant filter, which also contains the additives, depending on application) at 100,000km intervals (about once every few (3) years).
Thermostats
Another cause of similar overheating symptoms is a defective thermostat. If the t-stat doesn’t open completely, the anti-freeze flow won't be enough for high-load cooling. Weak t-stats are an even more common problem with some motor home and truck engines (vs. car), the t-stat closes when hit with the high-pressure pulsations of the antifreeze.
If you're unsure about any aspect of cooling system service, don't take a chance. Have your vehicle looked at by a professional service technician.
