BirdDog
New Member
- May 28, 2019
- 28
- Boat Info
- 1999 Sundancer 310DA
- Engines
- 2 Mercruiser 350 MAG MPI w/V-drives
1999 Sundancer 310 DA. 350 MAG MPIs. Starboard engine has developed a “squeal” that becomes a “shriek” at higher RPM.
Using my highly discerning ear (not), I first thought it was an idler pulley. Swapped in a new one and alternated it in the two positions. Not the cause.
I them bit off on a few online threads diagnosing such things that suggested the raw water pump bearing can wear and cause this. A new raw water pump later… nope.
Next thing I figured is that well… it must be the engine coolant pump bearings are near failure. So I spent a couple hours putting on a new coolant pump. Once I got everything put back together and started it up… success! The engine was running without the noise!
https://i.imgur.com/z4AIMV2.mp4
And then that success was short lived. After running for about five min at idle it started to “chirp”
https://i.imgur.com/apYUnlF.mp4
I pushed up the RPMs and it really got bad
https://i.imgur.com/a21NLc0.mp4
Hopefully the links work. Will try to imbed these tomorrow.
So I borrowed a friends mechanics stethoscope and best I can tell, this shriek is coming from the crank pulley.
For those with experience, is this the dreaded serpentine noise many encountered years ago due to pulley geometry issues that Mercruiser did a bracket recall/replacement on almost 20 years ago? I have no idea if these engines had the issue or were remedied. Next time at the boat I’ll do a check with a strait edge to make sure all the pulleys are on the same vertical plane. If they are not, then one more thing to remedy. But if they are all in alignment….
Or is this a more sinister sound? I used to rebuild small block 350s in the 1990s and am well familiar with them. But this noise is a new one for me.
Any and all useful info is appreciated, especially if it prevents me from replacing fully functional, albeit old parts, for nothing aside from process of elimination…
Regards
Ben
Using my highly discerning ear (not), I first thought it was an idler pulley. Swapped in a new one and alternated it in the two positions. Not the cause.
I them bit off on a few online threads diagnosing such things that suggested the raw water pump bearing can wear and cause this. A new raw water pump later… nope.
Next thing I figured is that well… it must be the engine coolant pump bearings are near failure. So I spent a couple hours putting on a new coolant pump. Once I got everything put back together and started it up… success! The engine was running without the noise!
https://i.imgur.com/z4AIMV2.mp4
And then that success was short lived. After running for about five min at idle it started to “chirp”
https://i.imgur.com/apYUnlF.mp4
I pushed up the RPMs and it really got bad
https://i.imgur.com/a21NLc0.mp4
Hopefully the links work. Will try to imbed these tomorrow.
So I borrowed a friends mechanics stethoscope and best I can tell, this shriek is coming from the crank pulley.
For those with experience, is this the dreaded serpentine noise many encountered years ago due to pulley geometry issues that Mercruiser did a bracket recall/replacement on almost 20 years ago? I have no idea if these engines had the issue or were remedied. Next time at the boat I’ll do a check with a strait edge to make sure all the pulleys are on the same vertical plane. If they are not, then one more thing to remedy. But if they are all in alignment….
Or is this a more sinister sound? I used to rebuild small block 350s in the 1990s and am well familiar with them. But this noise is a new one for me.
Any and all useful info is appreciated, especially if it prevents me from replacing fully functional, albeit old parts, for nothing aside from process of elimination…
Regards
Ben
