Dripping raw water

[Mark Gale]

The raw water pump on my 21 hp M25 Universal diesel has a steady drip when running from what appears to be a weep hole behind the impeller casing right below the impeller drive shaft. One mechanic says the shaft is worn and needs to be replaced. Another mechanic says this drip is normal and provides lubrication for the shaft. Who's right?The engine has about 900 hours and runs great. It can growl along all day at 2800 with no overheating. Then again, the water coming in from Lake Michigan is usually in the 60s.Thanks, --Mark

 

[Dave]

Raw water weep

Hi Mark:I had the same problem with my old boat with a universal MK12 engine. The folks at Blue water marine said the seal was worn and should be replaced. I got the parts and did it myself in about an 2 hours. Look the shaft over for wear and roughness. I would be wary of the mechanic who told you it was normal, it is not! Thorsen will have the parts neededGood luck, Dave

 

[Bob Rutland]

Sign to rebuild

The drip is a sign that it is time to rebuild your pump. If the shaft is ok , it's just a matter of replacing a seal. I had the same leak with our pump. I took it to my local dealer (Yanmar)he replaced the seal and bearings for less than $50. Good Luck, BobS/V H31 Lady Di II

 

[Gordon Torresen]

Third mechanic

The opinions of the two mechanics are flawed. One doesn't know and the other is jumping to conclusions. A seal needs to be replaced (actually two seals) to stop the water drip - it doesn't get better on its own.When replacing the water seal, a seal on the other side of the drip hole that keeps the oil in the engine is always damaged during the repair. Replace both seals making sure the lips are aimed in the proper directions.