Hi Guys,
Arrived in Mexico for the season last week. Boat partner had already splashed the boat, checked fluids and started both engines. (2002 5.7 Captains Choice with around 950 hours each) He was anxious to fish so we went tuna fishing the next day. After several hours we noted a loud roaring (whirring?) noise starting at about 1200 rpm on the port engine. It seemed to go away, or at least diminish so it could not be heard above about 2000 rpm. We got back to port, lifted the hatch and tried to find the noise while at the dock in neutral. It was there, came on suddenly at 1200, and surprisingly loud with the hatch up.
I had brought down a raw water pump (P105) for that side as it had developed a leak last spring and was dripping salt water, so I figured that was perhaps the source of the noise. We suspended fishing and I put on the new pump and changed the belt the next day (it was somewhat worn and getting loose). Started it up and the loud noise came back at 1200 rpm as before. No change at all. To me it sounded like it was from the front part of the engine. I did a scan at idle and found no codes thrown and all readings looked normal. I wanted to scan with the noise happening but turned out not to want to come back.
So I am flummoxed. I have addressed the most likely causes (the failing pump and the belt). The thing is intermittent and goes away entirely at lower rpms and sometimes at all rpms, so it is unlikely to be something mechanical like a valve train failure. I did note an occasional mild "squeek" from the engine when at idle so that is not entirely normal.
But when the new noise happens, it is loud! Has anyone experienced anything like this or might have some guesses as to where to go next?
The boat is pulled right now so next week I plan to loosen my new belt (never easy on the port side) and then carefully hand turn the alternator and circulating pump to see if the bearings feel rough. I will replace if I find them suspect.
Any suggestions or speculations would be welcome. I am sure it will eventually be found (hopefully not 20 miles offshore) so a headstart or road map would be useful.
Thanks for your help.
CaboJohn
PS On a related note, that raw water pump that I took off was installed new in January 2017. The one before it also developed a leak. Since that boat sees less than 6 month a year of use (and certainly not every day), that is a very premature failure of the shaft seal. Anything I could have done in the installation to cause such outcomes? I am always willing to learn!
Arrived in Mexico for the season last week. Boat partner had already splashed the boat, checked fluids and started both engines. (2002 5.7 Captains Choice with around 950 hours each) He was anxious to fish so we went tuna fishing the next day. After several hours we noted a loud roaring (whirring?) noise starting at about 1200 rpm on the port engine. It seemed to go away, or at least diminish so it could not be heard above about 2000 rpm. We got back to port, lifted the hatch and tried to find the noise while at the dock in neutral. It was there, came on suddenly at 1200, and surprisingly loud with the hatch up.
I had brought down a raw water pump (P105) for that side as it had developed a leak last spring and was dripping salt water, so I figured that was perhaps the source of the noise. We suspended fishing and I put on the new pump and changed the belt the next day (it was somewhat worn and getting loose). Started it up and the loud noise came back at 1200 rpm as before. No change at all. To me it sounded like it was from the front part of the engine. I did a scan at idle and found no codes thrown and all readings looked normal. I wanted to scan with the noise happening but turned out not to want to come back.
So I am flummoxed. I have addressed the most likely causes (the failing pump and the belt). The thing is intermittent and goes away entirely at lower rpms and sometimes at all rpms, so it is unlikely to be something mechanical like a valve train failure. I did note an occasional mild "squeek" from the engine when at idle so that is not entirely normal.
But when the new noise happens, it is loud! Has anyone experienced anything like this or might have some guesses as to where to go next?
The boat is pulled right now so next week I plan to loosen my new belt (never easy on the port side) and then carefully hand turn the alternator and circulating pump to see if the bearings feel rough. I will replace if I find them suspect.
Any suggestions or speculations would be welcome. I am sure it will eventually be found (hopefully not 20 miles offshore) so a headstart or road map would be useful.
Thanks for your help.
CaboJohn
PS On a related note, that raw water pump that I took off was installed new in January 2017. The one before it also developed a leak. Since that boat sees less than 6 month a year of use (and certainly not every day), that is a very premature failure of the shaft seal. Anything I could have done in the installation to cause such outcomes? I am always willing to learn!