My Volvo Penta 2003 Is Overheating

The Volvo Penta 2003 marine engine, whether used in inboard boats or inboard-outboard boats, can overheat and suffer significant damage. The causes of overheating in the Penta engine fall into four main categories, ranging from difficult-to-repair electromechanical problems to simple things like spending time chasing fish that hide from you in shallow places.

  1. Operating in Shallow Water

    • When you go boating in shallow water, such as a small creek, known for both huge fish and its shallow depth, your boat may "touch bottom." When it touches or drags over the silt on the bottom of a body of water, every bump and intake on the bottom of the boat picks up a covering of river mud. If the mud and bottom debris isn't quickly washed away by deeper water, it can clog the raw water pump or the drive water intakes on your Volvo Penta. In boats equipped with a heat exchanger -- like a car's radiator, but built into the bottom of the boat -- the heat exchanger may become covered with mud that prevents the heat exchange with the water beneath the boat, causing the Penta to overheat.

    Electrical and Electromechanical Causes

    • The thermostat and the sending circuit of the Volvo Penta may fail, according to the troubleshooting section of the Volvo Penta Owner's Manual. The thermostat controls the timing of the influx of cooling water into the cooling galleries around the engine's cylinders and in the exhaust manifold. If the thermostat fails to operate, the engine will overheat. The thermostat relies on the sending circuit to operate the circulating pump valve -- making a failed sending circuit another potential cause of overheating.

    Pump Failure

    • The circulating pump moves the water throughout the engine. If the pump fails because of an impeller that's damaged or simply falling apart because of age, the engine will overheat. A cracked pump housing on the Penta marine engine will cause reduced flow and the engine will overheat. The raw water pump is the pump that "picks up" water from the lake or river, for use by the circulating pump. If the raw water pump has a damaged impeller, possibly from sucking up mud or debris from the bottom, it will eventually fail. A broken raw water pump is another cause of overheating.

    Simple Stuff

    • Finally, before anyone goes boating, they should check all the water hoses and the belts on their Volvo Penta marine engine. The hoses transport the water from the raw water inlets to pumps, which cool the engine by their efforts. A hole in a hose can cause just as many problems as the most complex part of the cooling system. The circulating pump is driven by a belt that's driven by the crankshaft. If the belt that drives the pump breaks, the pump doesn't operate and the engine overheats. If the belt slips, the pump operates fitfully and may mimic a pump with a cracked housing. This is why you check the belts and hoses during the periodic maintenance inspections and before going boating.