MD2B Alternator V Belt Tension

[zinahewitt]

Hi All,

I have an Alternator

The alternator is connected to the Engine Flywheel using a V belt.


The Manual says.

It says test the belt by pressing and it should move 3-4mm under normal thumb pressure.
This is fine.
But
It says if an alternator is fitted ((which it is installed))) the tension should be so hard that it is just possible to get the pulley to slip by turning with one finger a wing on the alternator.

I put a video of what it looks like tensioned hard but where I can still turn it with one finger.

IMG_4160.MOV

drive.google.com

To me it seems too loose.

Any suggestions or should i just run it see if I get dust or noise over time ?

 

[Ted]

Your belt is way too loose. Deflection should be measured at the center of the longest unsupported section of your belt.

 

[Ralph Johnstone]

You might want to keep an eye on that belt because it's about to launch itself.

You want it to be something closer to this :

​

 

[zinahewitt]

You might want to keep an eye on that belt because it's about to launch itself.

You want it to be something closer to this :

View attachment 236232
​

Hi

Thanks for the picture.
I get what you are saying.
But why would the manual say I need to allow
""get the pulley to slip by turning with one finger a wing on the alternator."""
If I tighten it that much . I can't get the pulley to slip no matter how hard I push the alternator wing.

 

[Ralph Johnstone]

I see exactly what you're saying about their incoherant mutterings but haven't got a clue in hell about that of which they speak :

NOW I see why your belt is hanging like a limp ....................... well, best use your own imagination on that one. You could break a finger on the alt. fan before the pulley is going to slip. Just get it to 2-3 mm. deflection.

I keep my belt tension at approx. 50 lbs. as that's the minimum I can get away with, without the belt slipping. It feels pretty tight and limits the deflection to a couple of mm. I measure the tension with a Gates Kricket V-Belt Tension Gauge.

 

[zinahewitt]

I see exactly what you're saying about their incoherant mutterings but haven't got a clue in hell about that of which they speak :

View attachment 236236

NOW I see why your belt is hanging like a limp ....................... well, best use your own imagination on that one. You could break a finger on the alt. fan before the pulley is going to slip. Just get it to 2-3 mm. deflection.

I keep my belt tension at approx. 50 lbs. as that's the minimum I can get away with, without the belt slipping. It feels pretty tight and limits the deflection to a couple of mm. I measure the tension with a Gates Kricket V-Belt Tension Gauge.

Thanks for the guide, I have a kricket so I'll follow it.

Thanks a ton again!!!

 

[Ralph Johnstone]

If you want to go fancy (in a cheap sort of way), you may want to fabricate one of these for getting a tighter control when setting your belt tension :

Try to ignore the crap photography with the ghost hand in the way. What is supplying the belt tension is a cheap, galvanized turnbuckle with the ring on each end cut open and the ring is then bent to match the curvature of the sheave. Once you get the tension you want, you've got endless time to tighten the bolts on the moveable device to hold your tension.