Engine sound with and without fan cover

[Yakov]

This probably sounds like a silly question for those who have seen more than one Haflinger in their day, but I've only ever seen one, and it is far from perfect, so I have to ask all sorts of silly questions to make up for the lack of Haffie experience.

My question today is this: is it supposed to sound more shrill and whiny when the fan cover is off? Or is it just a worn bearing in the dynastart fan that I can hear better when the cover is removed?

[heinkeljb]

The fan cover will take away some of the noise you hear by the fact the air is being forced to go down over the barrels.

Not really a good idea to run the engine for more than a couple of minutes with out the cover as barrels do get hot quite quickly.

The Dynastart could well sound more "shrill" without the cover and that could be down to brushes, but as you say depending on the noise could also be bearings. One of the two I have taken apart, the first one had "sealed for life" bearings and the second had been modified to have a grease nipple put in to feed the rear bearing. Both felt smooth when being turned by hand, but when I sent them off to be reconditioned, they told me one of the front bearings was turning in the mounting at higher speeds, so they replaced it and glued it in with locktight.

Seems to work well!

John

[AustHaflinger]

In my experience the sound is basically the same in both scenarios but with the the covers on it is just a little more muffled and subdued.

Garry

[Goatwerks]

Remove the belt, check for shaft play , feel for roughness while rotating fan by hand.
If bearings are bad change them, if you need brushes, use VW 6v starter brushes.
(about $14US)

[Yakov]

Thanks for the responses!
I now feel I have reason to believe something might not quite be right. I only run the engine without the cover when setting the idle. I've seen how hot it gets, and what a difference clean engine tin on the cylinders makes.

I will check these things the next time I'm working on it.
I have checked the brushes before, but other than how much of them was left, I'm not sure what else to look for. Is there anything to look for on them?

[kerry460]

G,,day , an industrial stethoscope is very usefull for finding bearing noise .
or a through tang screwdriver works well .

kerry

[heinkeljb]

It's never going to be easy to describe a noise and for some one else to definitively be able to say whether it is right or wrong, but from your description, other than checking the bearings for wear / roughness and checking the brushes to ensure they move nicely in the holders and are not too short. That the surface they touch on the commutator is smooth and not horribly ridged , I don't think there can be very much else that is wrong.

Some engine just are nosier than others - but work perfectly well.

I take it the charging system appears to work correctly? The use of an ammeter and voltmeter would verify the actual values whereas the charge light can hide a multitude of weak / non-charge situations.

John

[Julian B]

If you have an iPhone or similar, take an "audio note" / recording of the noise and upload it; I did this once with a friend and it proved invaluable.

[Yakov]

It turned out that two of my fan blades were bent out of shape!
I feel dumb.
The machine sounds great now that they've been straightened out.

[heinkeljb]

One of the reasons why I said it was always going to be difficult to diagnose " a noise" from a description! I am glad you found the reason and were able to correct it.

Well done.

John