OVERHEATING CAUSES AND TROUBLESHOOTING FRESH WATER COOLED ENGINES
· Engine overheating can be a common problem on sailboats with diesel engines. If the engine overheats excessively, shut it down ASAP or damage could occur to the impellor or engine.
· Check the antifreeze level in the overflow reservoir. If empty, there may be a leak of antifreeze. Check the bilge for any antifreeze. If so, check hoses for leaks. Always carry spare antifreeze onboard your vessel. Once the leak is found and repaired, refill the reservoir. Let the engine cool then remove the pressure cap to check antifreeze level.
· If coolant is replaced, air can be introduced into the system causing an air block. If air gets in the cooling system, the system needs to be bled. This can be done by opening the coolant bleed valve (sometimes located near the thermostat housing) or with the engine running at high RPMs, remove the pressure cap. Refer to the engine manual to properly “burp” or “bleed” the coolant system.
· Overheating is frequently caused by an external blockage to the seacock intake or debris into the seawater strainer. With the engine shut down, close the seawater intake seacock and remove the strainer to check for debris.
· If the strainer is clear, momentarily open the seacock to see if sea water comes through. If so, the seacock is clear and most likely not the problem.
· Remove the raw water hose momentarily exiting from the heat exchanger to make sure raw water is flowing to the riser.
· Check the exhaust to make sure a steady stream of water flows from the exhaust pipe. If not, there could be a hole in the riser allowing gases to escape or a blockage in the exhaust hose.
· If the raw water system seems Ok, check for debris in the heat exchanger. A common problem is pieces of the zinc can break off inside the heat exchanger. This can cause an intermittent problem as the pieces can shift around inside the exchanger tube. To check this, remove the end cap and look inside for any debris.
· Other possible causes for overheating can be a bad impellor, loose or faulty belt, thermostat, low engine oil, clogged or faulty heat exchanger, bad riser and even the pressure cap or anti syphon valve. The sender or temperature gauge could also be bad.
· There could also be a bad hose or blockage in the hose. Check these hoses for leaks or blockage.
· If everything checks out OK, there could be something wrapped around the prop causing excessive stain while motoring under load.
· Engine overheating can be a common problem on sailboats with diesel engines. If the engine overheats excessively, shut it down ASAP or damage could occur to the impellor or engine.
· Check the antifreeze level in the overflow reservoir. If empty, there may be a leak of antifreeze. Check the bilge for any antifreeze. If so, check hoses for leaks. Always carry spare antifreeze onboard your vessel. Once the leak is found and repaired, refill the reservoir. Let the engine cool then remove the pressure cap to check antifreeze level.
· If coolant is replaced, air can be introduced into the system causing an air block. If air gets in the cooling system, the system needs to be bled. This can be done by opening the coolant bleed valve (sometimes located near the thermostat housing) or with the engine running at high RPMs, remove the pressure cap. Refer to the engine manual to properly “burp” or “bleed” the coolant system.
· Overheating is frequently caused by an external blockage to the seacock intake or debris into the seawater strainer. With the engine shut down, close the seawater intake seacock and remove the strainer to check for debris.
· If the strainer is clear, momentarily open the seacock to see if sea water comes through. If so, the seacock is clear and most likely not the problem.
· Remove the raw water hose momentarily exiting from the heat exchanger to make sure raw water is flowing to the riser.
· Check the exhaust to make sure a steady stream of water flows from the exhaust pipe. If not, there could be a hole in the riser allowing gases to escape or a blockage in the exhaust hose.
· If the raw water system seems Ok, check for debris in the heat exchanger. A common problem is pieces of the zinc can break off inside the heat exchanger. This can cause an intermittent problem as the pieces can shift around inside the exchanger tube. To check this, remove the end cap and look inside for any debris.
· Other possible causes for overheating can be a bad impellor, loose or faulty belt, thermostat, low engine oil, clogged or faulty heat exchanger, bad riser and even the pressure cap or anti syphon valve. The sender or temperature gauge could also be bad.
· There could also be a bad hose or blockage in the hose. Check these hoses for leaks or blockage.
· If everything checks out OK, there could be something wrapped around the prop causing excessive stain while motoring under load.