Grant Multipass 70/90 Reillo Burner Noisy

[luap2411]

Hi

Was looking for some advice.

As above have a Grant Multipass, about 12 years old. I have to say it's been excellent. A couple of years ago when the boiler first fired up after being on holiday for a week it was a bit noisy for the first minute or two and that was it.

Over the past week it has started to get noisy though. Sounds like bearings/fan. Today I took the cover off, convinced myself it was at the fan end of the motor shaft> so I took the fan cover off, not visible sign of fan touching anything, no play in bearings, didn't feel rough to spin.

Put it back together, and tried it just to check, and it was just as noisy. But now the heating has come on it seems no noise.

The only thing I can think of it that the oil in the tank was very very low this week, the noise started on Monday, we had oil delivered on Tuesday. Tank is 6ft below boiler so it has quite a bit to draw.

Maybe the pump sucked up some water/rubbish, or it had an air block. Having the burner out and disturbing it cleared it or moved the air so it bled through ?

Anyone have any ideas, been running now for 40 mins without drama !

 

[Burnerman]

The motor bearings have to be the favourite here....really very common.
Perhaps by splitting the motor they've gone quiet for a while, but the noise (droning, usually) will be back!
John

 

[luap2411]

Thanks burnerman, I didn't strip the motor, and when I fired it up after putting it back together it was still noisy. Half an hour later it was fine and still fine now ??

It's bizzare. But I'm expecting it to come back.

 

[Burnerman]

That'll be the Riello RDB burner I guess, so its either the motor bearings or the pump (which makes more of a 'zizzing' noise if its aereated and would give poor combustion if it was).
There is a plastic drive key between the motor and the pump and that shouldn't give any bother....just monitor the situation! Maybe the heat from the burner has taken up some bearing clearances.
John

 

[oilhead]

Maybe oil passing the shaft seal is going in the back of the motor and lubricating it. When it has stopped for a while and dried out, it makes a noise. Split the pump from the motor, if a leak is apparent, chage both.

 

[luap2411]

Here is the strange thing, it was noisy before I disturbed it, it was noisy when I reassembled. But after standing for 30 mins it's fine and has been all night (so far fingers crossed).

If the seal had gone and lubed the bearing it would surely be quiet when it first fires up and then get noisy as things warm up.

This only started happening on Monday morning when the oil in the tank was very very low. Normally with a bearing or failed seal you would expect the symptoms to come on progressively, not just appear from nowhere, and then seem to go away.

I strongly suspect it will come back, that's how my luck is at the moment ! But I'm also curious why, and secondly would like some ideas in preparation.

A pump and motor will probably be £200, and possibly another £30 if I knacker the fan taking it off. So there is a good financial interest in this for me !

Thanks for all the help so far.