Listen to my M25XPA

[Witzend]

http://www.youtube.com/watch?v=t38d2rg6EV8
I'm experiencing a dry bearing sound. It is very subtle. Started intermittent last year and now it is constant. It is unfortunately difficult to ascertain from my video except right at the end. The bearing in the alternator seems smooth. I suppose I could run for a short time with the belt off and see if it sounds different. My guess is it is the high pressure fuel pump. Does anyone have a clue what it might be and whether it is a serious problem, or me just being anal.

 

[Stu Jackson]

The bearing in the alternator seems smooth. I suppose I could run for a short time with the belt off and see if it sounds different. My guess is it is the high pressure fuel pump. Does anyone have a clue what it might be and whether it is a serious problem, or me just being anal.

Could be the "last" idea. Rare, literally unheard of, in our experience of a high pressure fuel pump issue.

Hard to run w/o overheating with no belt. I wouldn't. If only to check the alternator, relieve the belt tension, and turn by hand. If it spins freely, it's OK.

OEM alternator? Full batteries?

Any particular revs this happens?

Have you tried a stethoscope? Or a long screwdriver, handle to your ear?

Hard to hear WHERE the noise is coming from. Like a monaural point-and-shoot camera taking short videos.

Good luck.

 

[Witzend]

Running a short time is the key to not over heating. I agree with you about the audio not being able to pinpoint the source, but I was hoping that someone might be able to identify the sound rather than identify where it is coming from. I have tried the screwdriver on the bone below the ear trick and can not determine where it is most prominent.

 

[RAD]

How about a water pump bearing?......maybe do disconnect a belt and run for a short time

 

[Don12364]

Slightly slack alternator belt squeaking on the pulley as it slips?

As a young petrol head, one day I took my car to the garage because I couldn't locate a squeak in the engine bay.
The mechanic and I stood with the hood up watching the engine running.
He said - "Look away". I did and the noise stopped within five seconds.
I looked back again and nothing had happened but he was laughing.
He knew the fault and had taken the dipstick out and touched the side of the belt with it. A drop of oil from the dipstick had transferred to the belt and lubricated the pulley flange.
"No charge Sir".

 

[Witzend]

Slightly slack alternator belt squeaking on the pulley as it slips?

Familiar with that, not a squeak sound, more like a zizzing sound, again you can hear it best right at the end of the video. Both water pumps also appear to turn smoothly, but next time I will loosen belt for a moment to see it the noise disappears. Otherwise the engine runs great.

 

[RAD]

Familiar with that, not a squeak sound, more like a zizzing sound, again you can hear it best right at the end of the video. Both water pumps also appear to turn smoothly, but next time I will loosen belt for a moment to see it the noise disappears. Otherwise the engine runs great.

although they turn smoothly at 1500 rpm they might be making zizzing noise while turnning smoothly and I agree a dry bearing makes that sound

 

[Witzend]

I disconnected the belt and ran for a moment, noise still present, so it is not the alternator or belt driven pump, may still be the raw water pump for it is gear driven internally. Not sure whether this is something serious or not.

 

[RAD]

I disconnected the belt and ran for a moment, noise still present, so it is not the alternator or belt driven pump, may still be the raw water pump for it is gear driven internally. Not sure whether this is something serious or not.

Can that pump be removed and the engine started

 

[Merlin Clark]

Need to try what Stu said with the long screw driver or a piece of dowelling. Touch the various housings and brackets and when you hit the right one you will know it. I put my bent thumb on the end and the first knuckle in my ear.
If you have a long piratey pony tail this would be a good time for a hat.

 

[Witzend]

I will give the screwdriver ear drum location test again to try to localize the noise source once again.
Good question RAD, I know on my Sherwood, there is a shaft that is gear driven, not sure how I get into where i can inspect the gears to see if they are getting lubrication without major breakdown. I can see on the exploded view that there are 2 sealed ball bearing assemblies (#15 for all you gamers) they could be the source of the noise. I remember though, reading somewhere that if you pull the shaft out accidentally when changing the impeller that it's a bear to get back in.

 

[RAD]

What is the gasket # 22 for? water,oil cause thats what might keep you from running the engine without the pump attached,but by the looks of all those parts inside I'd take a large bet thats the problem maybe try the long screwdriver to the ear and that pump and see what happens

 

[Stu Jackson]

I remember though, reading somewhere that if you pull the shaft out accidentally when changing the impeller that it's a bear to get back in.

That's not true anymore. The really older engines, before my 1986, had a female inboard end to the pump shaft. It took me two years of getting up my nerve to take it out. Once I did I found out it had a MALE end which slid easily in and out.

Check your blow up diagram for your engine and your pump, and you'll most likely find you will not have this issue. Part #17 clearly has a MALE end. You do not have this problem. NOT.

 

[Witzend]

So if the seal were to fail, then raw water would enter the bearing and mess it up.
It would appear that the shaft will only pull out once you remove the plate #9 and then the seal #10,11,12, then maybe the entire assembly with the bearing will pull out, but it is hard to tell. There is certainly some clip rings holding the bearings onto the shaft.
Stu, did the bearings come out when you pulled yours?

 

[Stu Jackson]

Nope, the bearings stay in, the impeller and shaft slide out. Whenever I have a "raw water pump event" (like overheating or a clogged raw water inlet), I simply take the cover plate off the pump and pull out the impeller and the shaft. I have a new impeller and shaft (backup) always ready to go, along with a new face plate cover gasket. Your Sherwood pump has that bassackwards cover plate, but once the plate is off the impeller & shaft should easily be removed. I have an Oberdorfer. Pretty much the same guts, take a look at the Oberdorfer pump online at marinedieseldirect, same concept. http://www.marinedieseldirect.com/c...ervice=200151&printoperators=200157&comment1=

The pump body should hold the seals and bearings in.

Ya know, since we have the same engines, why not ask this question over on our C34 message board, we have lots of skippers who could help on this one, too, as well as the great guys here. http://c34.org/bbs/index.php/board,11.0.html

Try that, 'cuz I don't have a Sherwood pump, but I find it hard to believe that a pump's guts would fall out if it's just the impeller you're trying to change..