Belt squealing

[Kodiak45]

The belt on my dk40 will squeal on start up and go away after 30 sec or so. It will do this whether the engine is hot or cold. Any idea what would cause this and what to look at first for diagnosis? It doesn't do it every time, but at least 7 out of 10 starts.

 

[George2615]

First, is the belt tension correct? A loose belt will squeal on start up.
Second, As a belt ages it can stretch and get loose. Also a loose belt can get glazed from slipping causing a squeal.
Third, if the belt is good and adjusted correctly the squeal could be a bearing in the water pump or alternator that is starting to go.

 

[flyerdan]

It's the alternator belt, it creates more drag while producing additional amps to replace the charge used in starting, that's why it goes away once the load decreases. Belts shouldn't be run any tighter than necessary as it's hard on bearings, but they shouldn't be allowed to slip, as that can glaze them and lead to more slippage, etc.

 

[bspeedy]

Only two likely issues - adjustment or glazed belt. Tighten the belt. Replace the belt if it still squeals.

 

[Kodiak45]

I tightened it a good bit and we'll see how that does. I tightened it to about 1" or so of deflection. Hope that resolves this annoying issue

 

[Egon]

Belt dressing?

 

[Peter 315]

Belt dressing?

NO just retighten then if still squeals get a new belt

 

[Kodiak45]

NO just retighten then if still squeals get a new belt

I think that's best. I tried dressing and it was only a temporary fix if it helped at all

 

[BleedingOrange]

Before starting it, spray a bit of water on the belt. Once you start it, see if the squealing is still there, or not.
If still there, it,s a bearing, If it goes away, it,s the belt has been glazed.

 

[Peter 315]

I think that's best. I tried dressing and it was only a temporary fix if it helped at all

Working on the tractors is just as much fun as digging :laughing:

 

[Kodiak45]

Before starting it, spray a bit of water on the belt. Once you start it, see if the squealing is still there, or not.
If still there, it,s a bearing, If it goes away, it,s the belt has been glazed.

good to know. I'll try that. Thanks!

 

[flyerdan]

1" is still quite a bit of deflection, unless the pulleys are about two feet apart. Most books call for belt deflections of .125" - .475", depending on the span. Running as loose as possible is good for bearings and belt life, but you don't want to have to fuss with it a couple times a week, either.
Also, if this belt also drives the water pump it's even more critical to keep things turning.

 

[DieselBound]

As noted, be careful that the belt noise isn't due to a troubled accessory component. (on older VW TDIs an exploded, shredded belt, usually due to some component (AC, alternator or accessory belt tensioner) that has froze up or is horribly impaired, has been known to toss itself into the crank pulley area and effectively create a timing belt failure on top of it all!)

I've used sandpaper as well as bar soap. Dangerous operation, though.

 

[Kodiak45]

1" is still quite a bit of deflection, unless the pulleys are about two feet apart. Most books call for belt deflections of .125" - .475", depending on the span. Running as loose as possible is good for bearings and belt life, but you don't want to have to fuss with it a couple times a week, either.
Also, if this belt also drives the water pump it's even more critical to keep things turning.

Then the belt was definitely very loose before I tightened it and it must be stretched quite a bit as there isn't much adjustment left in the bracket after adjusting to 1". I'll go ahead and get a new belt and set it at about .5"