Belt slipping?

[Richard]

I was out cutting a field yesterday. I noticed a bit of a burnt smell. Pretty much the exact smell if you are smoking a drive belt on a pully.

I have noticed lately that the tractor keeps running near hot. Hmmm.... do I have water/antifreeze mix in radiator? Yep. Is radiator unobstructed? Yep.

Now, I DID recently rebuild all three hydraulic motors for the flexwing mower as well as the hydraulic pump to power them. EACH one of them was much stiffer to turn after rebuild than before (which I'm attributing to tighter sealing now)

Other than that, nothing has changed. I historically cut the big hill in 3rd gear going up/down....and sometimes in 4th gear up/down. Yesterday I was in 2nd gear or 3rd gear with T/A engaged, slowing me down a bit.

That said, the grass was waist high so I know that was also adding a strain.....BUT..... I go back to every now & then catching a wiff of that burnt smell again (as in I smelled it again)

I'm beginning to wonder/suspect that my water pump might be starting to freeze up on me, hence the burnt belt smell and higher temps. I might add that when I'm going home, engine RPM's are down, the engine will easily cool down to or just below (on the cool side) of the first mark on the gauge.

Oh.... and the other day when I was cutting a different field, I was going in/out of T/A and during one of those lurches, I DID notice a puff of smoke from the front of the engine, along with again, that burnt belt smell. So I'm thinking that the pump is creating some resistance and when the RPM's jumped up it spun the belt a bit, creating some smoke.

Thoughts?

(no, I've not yet had time to dig into it and take anything apart)

 

[Roadworthy]

Before replacing the water pump I'd check my belt tension. If it's good and slipping anyhow replace the belt. They can become glazed, especially from slipping. You could even invest in some belt dressing compound. If the problem continues it may indeed be time to investigate water pump replacement.

 

[Richard]

The belt is essentially brand new. I replaced it last year as the one that was on there was looking ragged.

I will however, admit I'd not thought of the belt, perhaps it's stretched a bit and does need tightened. That could explain everything!

 

[Richard]

An update: Just finished some of my morning work so went out to look at the tractor.

Low & behold, when I pushed on the fan belt, it was about as floppy as floppy can be and still be in the grooves.

That explains a LOT!

I suppose I would have found it, after I bought a new water pump & thermostat to replace.... so I'm glad I looked first!

I'll get that tightened up this weekend and cut something to see what happens.

 

[zzvyb6]

So, Why is the tractor running Hot ? The power level would be the same or less with a slipping belt. Or the belt is slipping because the drag from the implement is actually higher. This may even have stretched the belt.

 

[Richard]

I'd contend the tractor is running hot because the fan RPM's are way less than the engine RPM's so it's not pulling air through the radiator as much as it should yet, the engine is still screaming at PTO speed creating the heat.

Since this belt only goes from the crank to the fan to the alternator, the implement can do whatever it wants and it won't affect the belt (though every now & then the engine RPM's do die down under load)

Even if the belt is stretched, I have a LOT of adjustment room so I can pull that back out. I think when this went on, I recall that the belt was a touch short (the alternator was crowded to about as small as it could go)

I also tend to keep an eye on the ammeter and I've never noticed it operating differently. When I've got the lights blazing, it's showing discharge, I turn lights off and it immediately jumps back up to neutral. So the drag needed to turn the alternator must be less than the drag needed to turn the fan/pump so the charging has been evidently working fine but the fan/pump have not.

I'll know more and for certain after I tighten it and go knock out another (very tall grass) field. I'm expecting that I'll be able to do my usual 4th gear or maybe 4th gear with T/A to slow it down a touch.

 

[PILOON]

You might also want to use a belt dressing of some sort.
Often comes as a wax like bar that you rub on as the belt spins.
Just watch out for your fingers.
I think there is also a spray available.