What to expect if an Idler Pulley or Alternator fails

[Slipshodman]

Hi All,

I will try and make this as short as I can.
I had mentioned in a reply on another thread that I have a noisy idler pulley, wines pretty loud with the rev's of the engine.
Finally got it to the dealer who believes it is the alternator not the idler pulley.
They will be replaced the alternator under warranty but I could only get it booked in mid next month (Feb).
So still 3 weeks away. The dealer recons it will be fine, just noisy. not sure i believe that but not much I can do.

I have a road trip ahead before its replaced, the plan was not to go off road at all just in case it needs towing, But going over the planning I realised I have a couple of beach runs to get to some camp grounds.

I am reasonably mechanically savvy but definitely not a mechanic,
So I am hoping some of the more mechanically minded might be able to help me understand what to expect if the alternator (or idler pulley) fails
I assume it will throw the belt if one fails, but
Will the JT just stop to protect itself, go into a limp mode
I know I will loose power steering and have limited battery power as the alternator would not be working
Cooling should still occur for some time as the fan is electric

I will be with another jeep so a short assisted tow on sand could be an option if the JT doesn't shut it self down

If you guys could help me to understand what behaviour to expect from the JT if either alternator or idler pulley fails would be appreciated

(@ShadowsPapa @Gvsukids , I hope you don't mind me asking directly, you both have way more knowledge than myself) and anyone else with the mechanical knowledge welcome

Side note- over here parts are not as easy to get in the US otherwise I would replace it myself pre the trip

Cheers

Sponsored

 

[Lost1wing]

Electric powersteering! That will kill the battery quicker once you lose alternator power. I'm sure you will get some message alerting you pull over. Cooling will be a problem pretty quick since the water pump will stop circulating water.

I have driven on squeaky idler pulley for a good bit of time. My neighbor is still driving his squeaky tensioner pulley since 2016. I'm not telling you to forget about it, just get it on the to do list and order your parts.

 

[ShadowsPapa]

You'll lose AC, alternator, water pump.
As a self-preservation move, it may shut off the power steering pump among other things.
If a bearing goes, it can cause a belt to do weird things like whip around and break other stuff.
it's hard to say, not being there and directly hearing it, if it's a bearing noise or what, but if it's a bearing, it won't get better.
The truck will likely shut down shortly.

 

[Lost1wing]

Hi All,

I will try and make this as short as I can.
I had mentioned in a reply on another thread that I have a noisy idler pulley, wines pretty loud with the rev's of the engine.
Finally got it to the dealer who believes it is the alternator not the idler pulley.
They will be replaced the alternator under warranty but I could only get it booked in mid next month (Feb).
So still 3 weeks away. The dealer recons it will be fine, just noisy. not sure i believe that but not much I can do.

I have a road trip ahead before its replaced, the plan was not to go off road at all just in case it needs towing, But going over the planning I realised I have a couple of beach runs to get to some camp grounds.

I am reasonably mechanically savvy but definitely not a mechanic,
So I am hoping some of the more mechanically minded might be able to help me understand what to expect if the alternator (or idler pulley) fails
I assume it will throw the belt if one fails, but
Will the JT just stop to protect itself, go into a limp mode
I know I will loose power steering and have limited battery power as the alternator would not be working
Cooling should still occur for some time as the fan is electric

I will be with another jeep so a short assisted tow on sand could be an option if the JT doesn't shut it self down

If you guys could help me to understand what behaviour to expect from the JT if either alternator or idler pulley fails would be appreciated

(@ShadowsPapa @Gvsukids , I hope you don't mind me asking directly, you both have way more knowledge than myself) and anyone else with the mechanical knowledge welcome

Side note- over here parts are not as easy to get in the US otherwise I would replace it myself pre the trip

Cheers

Are they sure the alternator is the squeal?

 

[ShadowsPapa]

Electric powersteering! That will kill the battery quicker once you lose alternator power. I'm sure you will get some message alerting you pull over. Cooling will be a problem pretty quick since the water pump will stop circulating water.

I have driven on squeaky idler pulley for a good bit of time. My neighbor is still driving his squeaky tensioner pulley since 2016. I'm not telling you to forget about it, just get it on the to do list and order your parts.

Yeah, there's a lot of ways a bearing can go - they can run a fairly long time, or die quickly. Serpentine belts mean a whole lot of tension is on the belt and thus bearings.
I've seen 'em go both ways - and it's really hard to say.

 

[Lost1wing]

If you are handy, perhaps you can take the tension off and inspect the pulleys yourself.

Yeah, there's a lot of ways a bearing can go - they can run a fairly long time, or die quickly. Serpentine belts mean a whole lot of tension is on the belt and thus bearings.
I've seen 'em go both ways - and it's really hard to say.

Not hard to take the belt off and put your hand on the moving parts. Easy to pick out a bad idler or tensioner pulley. You can even spin the alternator to see if it is dragging. Do these alternators have a one-way clutch on them? Squeaks that start out when cold and go away once warm tend to be pulley bearings. They will also scream at higher rpms. There's a lot of guessing to be had. We know it is not the powersteer pulley squeaking!

 

[Lost1wing]

Yeah, there's a lot of ways a bearing can go - they can run a fairly long time, or die quickly. Serpentine belts mean a whole lot of tension is on the belt and thus bearings.
I've seen 'em go both ways - and it's really hard to say.

Note on an accessory belt tensioner failure. Like you said, wild things can happen. Imagine trying to help someone out who thought it was just a broken belt. You go to take it apart but you find the tensioner buried into the engine timing belt cover. Then you take the timing cover off to not find the timing belt on an interference engine. How to explain to a friend that his engine was toast? It didn't go well.

 

[Slipshodman]

Thanks for sharing your knowledge everyone.
I can't cancel the trip so I did want to understand what to expect if it fails.
Fingers crossed it won't.
(Hadn't thought of the water pump, and didn't know the power steering was electric, ya learn something new everyday)

As for diagnosis, the dealer was pretty sure, sure enough to order a new alternator (and if they are wrong they will carry that cost) they had it in with one of thier mechanics for well over an hour while he was under the hood so can only assume he/she knew what they were doing to identify the cause of the noise.

Thanks again

 

[bd100]

Rent something for the trip. Cheaper than massive engine failure on the road.

 

[ShadowsPapa]

Australia - on our bucket list of places to visit. Almost did but the trail end of the Covid mess in the world had us cancel our planned trip.

Sponsored