mouse in the machine

[pole rigger]

Good morning experts, hope this isn't too taxing but here goes! Gravity fed domestic central heating powered by Grant outdoor boiler, Riello rdb1 burner. After 7 years system works as it should having been serviced anually.
Recently a squeak has developed which is quite high pitched and disappears two or three minutes after the boiler firing. It is not a continuous noise but occurs 2/3 times per second.
Have changed the oil pump coupling but this has made no difference, there was no contamination in the oil feed or pump itself. There was a very small ammount of brown staining in the old coupling and some resistance to turning on the pump shaft but I am not sure how much resistance there should be.
I suspect the pump but of course could be motor bearing.
What really puzzles me is why, if there is a bearing problem in the pump or motor, the 'squeak' isn't a continuous 'squeal'
Any advice would be appreciated.

 

[dontknowitall]

Might be something in the fan area or fan rubbing against the housing or could be the motor bearings.

 

[REDSAW]

could be Florence,
or is that something else?.

 

[Best]

That sounds like a motor bearing. They can do exactly that, - rapid squeak from cold start for a few minutes, slowly reducing & stopping. Usually the bearing on oil pump side of motor, but normally better change both while you have motor apart. If a bearing is beginning to seize a bit, it may try to turn in motor casing, which would cause same noise till it frees up. Not much chance of it being a worn oil pump, as they tend to keep making a grinding noise or a high pitched noise.

 

[dontknowitall]

One of our cats is called Mouse.

 

[pole rigger]

Cheers Best, Iv'e just stripped the unit to check the fan and there are no rub marks anywhere. Spun the fan and the motor turned quite freely with no noise and no noticeable play on the shaft. Was going to remove the pump to see if the squeak was still there but most probably it wouldn't do it if the motor wasn't under load.
I think you are right about the motor bearing. The fan doesn't look very robust and may be damaged trying to remove it from the shaft so best option may be to fit new motor and fan, refurb the old one in the workshop, then sell it on later. Besides, at this time of the year, my dear wife won't allow the heating to be off for more than an hour!!

 

[Best]

If you are careful, you normally should be able to get away with just 2 bearings. Spray oil where fan joins shaft, then slacken Allen screw. If fan won't pull off, don't try to prise it or you will twist it. Try holding other side of motor from turning ( when oil pump removed), & turn fan on shaft by hand & twist off.

 

[Hardy1]

when i read the thread i actually thought you had found a rat or mouse or something somewhere lol, went out to a service today and found rat droppings inside the boiler where the gas valve etc are.

 

[REDSAW]

One of our cats is called Mouse.

thats just cruel, woman!!!!.

 

[pole rigger]

Thanks Best, I have soaked the shaft with wd 40 so when I get back on tuesday I will give it a try.I also noticed that there is agroove around the spigot so I think it may be possible to use a small puller if the twisting doesn't work, one way or the other------

 

[pole rigger]

strangely enough I did actually find a mouse nest in the boiler casing today !! Good place to be this time of year.

 

[Best]

Thanks Best, I have soaked the shaft with wd 40 so when I get back on tuesday I will give it a try.I also noticed that there is agroove around the spigot so I think it may be possible to use a small puller if the twisting doesn't work, one way or the other------

Wd 40 will help. 9 out of 10 fans come off ok with a bit of patience. If you had some sort of tool to jam in the " slot " of the pump side of motor, where the plastic pump drive normally goes, & turn fan on shaft. When you get fan off, clean shaft with emery paper & file the burr on end of shaft that is left in manufacturing. Put a little grease on shaft when refitting fan,