- Joined
- Mar 1, 2000
- RO Number
- 6
- Messages
- 231
Times not always on your side
The importance of regular maintenance can never be stressed enough. The owners manual usually spells out just what exactly one should do to prevent premature failure.
As we move into a new century, many of us have taken these procedures for granted, often ignoring the dangers of those actions. We depend on lights and buzzers to tell us that it's time to pay attention to our cars, boats, and other machinery. But unfortunately, the warning device doesn't always work as designed by the manufacturer. There may be circumstances under which a damaging situation can arise, and the warning lights and buzzers don't activate. Although we'd all love to blame the manufacturer, and some blame does lie there, the truth is that we need to ask ourselves, did we do all we could do to prevent damage to our engine or boat.
The answer to that question can best be answered by one good example. The manufacturer for brand XYZ, produces a product that recommends that the water pump impeller be replaced every season. Brand XYZ recently improved their design for a certain water pump model, claiming the benefits of it's new design. The older model pump, (in production for over twenty years) had an intolerance to running dry but contrary to the recommended service interval, typically, lasted several seasons. When it started to fail, for what ever reason, the engine would over heat, the lights and buzzers would go off and the owner would know it was time for a new impeller.
The new model water pump had all the signs of a successful replacement to it's dependable predecessor, until that frightful day, when the new product was handed to "The Retail Public".
Note the ragged edge on the impeller sealing lip of the impeller on the left (red arrow). This impeller burned due to the ingestion of sea weed, and would operate at normal temperature up to 3200 RPM but the engine would overheat above 3500 RPM. No real damage done because the experienced owner knew what to do and had the boat serviced. The one on the right (blue arrow) cost the manufacturer an engine because the novice owner didn't notice the very slight increase in operating temperature. This owner continued to operate this engine for half a season until the engine just would not start. To make matters worse, the engine was replaced, and the new engine failed again, 20 hours latter. (shame on that dealership)
The problem is air ingestion into the cooling system by the sterndrive water-pump. Instead of reduced water flow, like the old pump, when this pump fails, it sucks air.... and lots of it. So much that the temperature senders for the gauge and buzzer are fooled into thinking every thing is OK. When in reality the heads of the motor are hotter than Blazes.
Being careful and replacing this water-pump every season should keep you out of trouble, but watch that sea weed....
Note : There was a service bulletin concerning corrosion and this water-pump, as well. It should be referred to when servicing this water pump. This corrosion Definitely will cause engine failure, if not attended to.
The Mercruiser Gen II water pump should not be ignored until a overheat is experienced. Serious damage could have occurred to the engine long before the overheat warning buzzer goes off.
The fault lies in the tendency of this pump to ingest air/ exhaust gas into the cooling system. Corrosion develops under the pump gasket and warps the water pump base plate causing the gasket to leak. The water and air mixture allows head temperature to run much higher than it should.
Seasonal service should prevent this from happening and the potential for engine damage. Usage in salt and/or brackish water requires special care when servicing this pump.
Note corrosion surrounding the pump housing at the base of the pump.
A closer view shows the factory paint in still on the gear housing... unfortunately.
Removing the paint shows that the corrosion is quite extensive under the paint.
Carefully remove all the dead paint.
And sand the surface clean.
Paint the bare casting with Zinc chromate primer then with regular paint before applying gasket sealing compound. Complete the assembly of the water pump per the manual.
At the center right of the picture you will note a piece of debris is clogging the weep hole of the water pump base plate. This hole needs to be kept clear and care needs to be used when applying the gasket sealing compound so that the hole does not get clogged with sealer during assembly.
The above information should be used in addition to your service manual.
The importance of regular maintenance can never be stressed enough. The owners manual usually spells out just what exactly one should do to prevent premature failure.
As we move into a new century, many of us have taken these procedures for granted, often ignoring the dangers of those actions. We depend on lights and buzzers to tell us that it's time to pay attention to our cars, boats, and other machinery. But unfortunately, the warning device doesn't always work as designed by the manufacturer. There may be circumstances under which a damaging situation can arise, and the warning lights and buzzers don't activate. Although we'd all love to blame the manufacturer, and some blame does lie there, the truth is that we need to ask ourselves, did we do all we could do to prevent damage to our engine or boat.
The answer to that question can best be answered by one good example. The manufacturer for brand XYZ, produces a product that recommends that the water pump impeller be replaced every season. Brand XYZ recently improved their design for a certain water pump model, claiming the benefits of it's new design. The older model pump, (in production for over twenty years) had an intolerance to running dry but contrary to the recommended service interval, typically, lasted several seasons. When it started to fail, for what ever reason, the engine would over heat, the lights and buzzers would go off and the owner would know it was time for a new impeller.
The new model water pump had all the signs of a successful replacement to it's dependable predecessor, until that frightful day, when the new product was handed to "The Retail Public".
Note the ragged edge on the impeller sealing lip of the impeller on the left (red arrow). This impeller burned due to the ingestion of sea weed, and would operate at normal temperature up to 3200 RPM but the engine would overheat above 3500 RPM. No real damage done because the experienced owner knew what to do and had the boat serviced. The one on the right (blue arrow) cost the manufacturer an engine because the novice owner didn't notice the very slight increase in operating temperature. This owner continued to operate this engine for half a season until the engine just would not start. To make matters worse, the engine was replaced, and the new engine failed again, 20 hours latter. (shame on that dealership)
The problem is air ingestion into the cooling system by the sterndrive water-pump. Instead of reduced water flow, like the old pump, when this pump fails, it sucks air.... and lots of it. So much that the temperature senders for the gauge and buzzer are fooled into thinking every thing is OK. When in reality the heads of the motor are hotter than Blazes.
Being careful and replacing this water-pump every season should keep you out of trouble, but watch that sea weed....
Note : There was a service bulletin concerning corrosion and this water-pump, as well. It should be referred to when servicing this water pump. This corrosion Definitely will cause engine failure, if not attended to.
The Mercruiser Gen II water pump should not be ignored until a overheat is experienced. Serious damage could have occurred to the engine long before the overheat warning buzzer goes off.
The fault lies in the tendency of this pump to ingest air/ exhaust gas into the cooling system. Corrosion develops under the pump gasket and warps the water pump base plate causing the gasket to leak. The water and air mixture allows head temperature to run much higher than it should.
Seasonal service should prevent this from happening and the potential for engine damage. Usage in salt and/or brackish water requires special care when servicing this pump.
Note corrosion surrounding the pump housing at the base of the pump.
A closer view shows the factory paint in still on the gear housing... unfortunately.
Removing the paint shows that the corrosion is quite extensive under the paint.
Carefully remove all the dead paint.
And sand the surface clean.
Paint the bare casting with Zinc chromate primer then with regular paint before applying gasket sealing compound. Complete the assembly of the water pump per the manual.
At the center right of the picture you will note a piece of debris is clogging the weep hole of the water pump base plate. This hole needs to be kept clear and care needs to be used when applying the gasket sealing compound so that the hole does not get clogged with sealer during assembly.
The above information should be used in addition to your service manual.