Raw water pump question/problems

[Malcolm]

In August I noted that my replacement Sherwood raw water pump on my M35B was bleeding water through the holes which I assume were provided to relieve leakage pressure before the water gets to the bearings and the engine.

Question 1
This pump is a complete replacement pump. When I compared it to the original pump which I had as a spare I noted that these vent holes are taped over and the tape is painted gray ie. Universal installed and painted the engine with the tape in place. The tape looks to be reasonably heavy - as if it was intended to stay there. My concern is that it defeats the purpose - and that is what is on the engine now. Why is the painted tape there and should I remove it?

Question 2
I disassembled to pump I removed this summer and noted that the problem of leakage was caused by a circlip which is worn out. I expect the circlip is supposed to hold the seal elements tight so the seal works. A sliver remained of the circlip. Why would there be rotation relative to the circlip?

Question 3
To make the pump I removed into a spare, should I replace the water seal, the bearings and engine oil seal? what is the best way to do this? The leak hadn't been for more than 22 hours (probably much less). Raw water is lake water. The oil level on the engine has not increased.

Background - I had replaced the complete original pump 2 summers ago as a precaution (since while raising anchor we ran the original for less than 10 minutes without water after starting a cold engine - the original still worked another 21 hours without a problem before I replaced it).

[stu jackson c34]

If your pump is weeping, the seals are gone and need to be replaced. Any cover over the weep holes should be removed. There was a recent discussion of this on this board recently, not too long ago, as I recall...

www.marinedieseldirect.com has blow up diagrams of the pump.

If you're handy, change the seals and bearing yourself, it can be done with deep well sockets as a tool. If not, have a shop do it, but it'll cost almost as much as a new pump, which is NOT necessary, unless you have a good handy friend.

[serena]

Do not leave tape on weep holes! These holes are designed to indicate the need to change the water pump due to a failed water seal. As you indicated water will be pumped into the crankcase if left unrepaired with tape covering weep holes. If water enters the crankcase it won't be long and the oil will emulsify with catastrophic results, ie potential engine failure. I experienced a "diesel runaway" with my M35B when the weep holes plugged forcing salt water into the crankcase and subsequent freezing up of the fuel injector pump causing the engine to race at 4000-5000rpm. This was no fun. So, moral to the story is keep your weep holes on the raw water pump open and if you see any sign of drainage, replace the raw water pump assembly unless you can rebuild it.
Mike Serena

[Steve Frost]

Mike,

Agreed that the water pump should be changed.

Your run away engine as I stated in response to your Ask The Experts inquiry is most unlikely to have been caused by a siezed injector pump. If the injector pump seizes the engine quits. A siezed governer or control rack could cause this but, the type of bearing used in those areas would likely run for many hours with no lubrication at all. The more likely cause for runaway is water filling the oil sump (oil floats on water) raising the oil level to the point that it is foced past the piston rings and the engine starts running on engine oil uncontroled. The only way to stop this type of run away is to obstruct the air flow. About two to three quarts over service or increase of the oil level caused by water incursion can cause this.

The engine I installed on my last boat experienced this, I purchased it as a core and rebuilt it.

[serena]

Steve, I certainly agree with you regarding my engine overrev. I am only passing on what the local Westerbeke authorized dealer/mechanic told me. Would the crankcase oil flow pass the rings if the rings are good? That would explain why I was unable to shut off the fuel as it was running on crankcase oil and not diesel. I am still without an engine. It is due to be shipped tomorrow. Can't wait to get it installed and get back out there.
Mike Serena