Starts but belt does not spin

[JacobVS]

So I am now having issues with my mj, it’s a 89 2.5l and has been running pretty good up until today.
I drove her today to pick up some stuff started great and ran great. When I went to head home she would not start. I found out my oil was very low refilled it and now something isn’t working.

 

The engine starts and runs but the belt does not spin. I am not sure what the issue is and am looking for some help.

[eaglescout526]

Like belt isn’t spinning at all? Sounds like it’s slipped off the harmonic balancer. 

[Eagle]

Is the belt tight? If so, there should be some rather loud noise and a smell of burning rubber.

 

Basically, there's a good chance one of the pulleys the belt runs over has a seized bearing: Water pump, alternator, a/c compressor (or idler), power steering pump.

[89 MJ]

If the belt is on and tight, the water pump and alternator being seized would be my first two suspects. 

[eaglescout526]

41 minutes ago, Eagle said:

(or idler)

2.5L didnt get one with an AC delete. Unless the OP has something like my 84 where its an aftermarket set up with an idler.

[JacobVS]

1 hour ago, eaglescout526 said:

Like belt isn’t spinning at all? Sounds like it’s slipped off the harmonic balancer. 

It’ll spin a bit but I didn’t want to run it long without it working

[JacobVS]

1 hour ago, Eagle said:

Is the belt tight? If so, there should be some rather loud noise and a smell of burning rubber.

 

Basically, there's a good chance one of the pulleys the belt runs over has a seized bearing: Water pump, alternator, a/c compressor (or idler), power steering pump.

Sure seems tight, how much play should it have when it’s tight?

[JacobVS]

1 hour ago, 89 MJ said:

If the belt is on and tight, the water pump and alternator being seized would be my first two suspects. 

That’s my thoughts too

[JacobVS]

48 minutes ago, eaglescout526 said:

2.5L didnt get one with an AC delete. Unless the OP has something like my 84 where its an aftermarket set up with an idler.

All stock on this one 

[89 MJ]

The belt should have less than an inch of movement if it’s tensioned properly. I’d pull the belt off and figure out what isn’t spinning and replace it. 

[JacobVS]

2 hours ago, 89 MJ said:

The belt should have less than an inch of movement if it’s tensioned properly. I’d pull the belt off and figure out what isn’t spinning and replace it. 

 

Thanks for the Advice I hope to get started on it tomorrow.

[pizzaman09]

What is the condition of the harmonic balancer rubber?  Could the center be spinning inside the outer ring?

[watchamakalit]

17 minutes ago, pizzaman09 said:

What is the condition of the harmonic balancer rubber?  Could the center be spinning inside the outer ring?

I would think Something would have to put allot of tension on the belt for that to happen.  Seems the balancer would throw the belt or come apart before that occurred.

 

Edit: I would pull the belt and check all the pulleys to see what turns.

[eaglescout526]

25 minutes ago, pizzaman09 said:

What is the condition of the harmonic balancer rubber?  Could the center be spinning inside the outer ring?

Oooooo I didnt think of this but I can see there not being enough material left on the balancer to drive the pulleys. 

[pizzaman09]

I've seen an alternator locked solid on an XJ, if the balancer rubber is weak, then maybe it powers through and slips instead of burning the belt up.

[JacobVS]

On 12/21/2024 at 11:54 AM, pizzaman09 said:

I've seen an alternator locked solid on an XJ, if the balancer rubber is weak, then maybe it powers through and slips instead of burning the belt up.

 

On 12/21/2024 at 11:05 AM, eaglescout526 said:

Oooooo I didnt think of this but I can see there not being enough material left on the balancer to drive the pulleys. 

 

On 12/21/2024 at 10:57 AM, watchamakalit said:

I would think Something would have to put allot of tension on the belt for that to happen.  Seems the balancer would throw the belt or come apart before that occurred.

 

Edit: I would pull the belt and check all the pulleys to see what turns.

 

The the alternator was bad and I am not struggling to find one do you guys got any tips on where I can find one?

[eaglescout526]

18 minutes ago, JacobVS said:

 

 

 

The the alternator was bad and I am not struggling to find one do you guys got any tips on where I can find one?

This has me confused. Are you having a hard time finding an alt as theyre just later GM/Delco Alts. Now if yours is doesnt have AC, yes I can see why your having an issue cause the pulley is different but just take your old pulley off and swap it to the new alt and give them the old alt with the new pulley as the core and move on. If you have AC, finding an alt should be cake.

[JacobVS]

2 minutes ago, eaglescout526 said:

This has me confused. Are you having a hard time finding an alt as theyre just later GM/Delco Alts. Now if yours is doesnt have AC, yes I can see why your having an issue cause the pulley is different but just take your old pulley off and swap it to the new alt and give them the old alt with the new pulley as the core and move on. If you have AC, finding an alt should be cake.

 No ac, I’ll have to look into reusing the pulley, the 61amp alt is the one I need but would a 74 amp fit with the reused pulley?

[eaglescout526]

Yeah a 74 amp will do. The only reason why you’d get higher amps is if you’re running more stuff like say fog lamps or a winch or off road lights and need the amps to run them. But I’d just get the highest amp, swap the pulley and call it a day

[Pete M]

more power = better    

[GonzoTheGreat]

Buy the 74amp, swap the pulley (and spacers), and if I recall, you’ll have to clock the case halves 60 degrees to make the rear mounting bolt line up.

[JacobVS]

18 hours ago, GonzoTheGreat said:

Buy the 74amp, swap the pulley (and spacers), and if I recall, you’ll have to clock the case halves 60 degrees to make the rear mounting bolt line up.

 

On 12/28/2024 at 11:37 PM, eaglescout526 said:

Yeah a 74 amp will do. The only reason why you’d get higher amps is if you’re running more stuff like say fog lamps or a winch or off road lights and need the amps to run them. But I’d just get the highest amp, swap the pulley and call it a day

I’ll be doing that then, thanks for the help