Alternator frozen

Topic: Alternator frozen (Read 1169 times) previous topic - next topic

Alternator frozen

May 15, 2025, 02:19:35 pm

Good afternoon for most of you,

Just tried to start the coach, getting ready for a trip in June. Last time I had it running was Nov.

It started right up but there was a serious squealing noise and when I opened the engine compartment, I found the main serpentine belt that drives the pulley for the A/C and the alternator broken.

I can turn all the pulleys except the crankshaft (no surprise) and the alternator. I assume I should be able to spin it by hand and that it is frozen. The alternator was replaced by FOT about 10 years ago.

Can you confirm that I should be able to spin the alternator? If so, It's time to start learning about alternators and sourcing a replacement.

I think I should be able to plug the coach back-in to a 30A circuit and then run the engine by turning on the boost switch. Is that also correct?

Thanks,

Rich

Re: Alternator frozen

Reply #1 – May 15, 2025, 02:27:36 pm

Rich,

Where are you located? Which alternator do you have?

Yes, you should be able to spin the alternator by hand.

But, very likely, the alternator can be rebuilt for a fraction of replacement cost.

Re: Alternator frozen

Reply #2 – May 15, 2025, 02:31:40 pm

Rich,

Yes, you should be able to turn a "good" alternator by hand. I don't think I have ever had one freeze up completely, but I guess it could happen.

Search on the Forum for Delco 28Si. I installed one of those several years ago and have been very happy with it.

If you plug into shore power, your inverter/charger should charge both battery banks (boost switch on) and the engine should run fine on just the batteries (no alternator).

Re: Alternator frozen

Reply #3 – May 15, 2025, 02:38:39 pm

Brett,

I'm near Dayton, Ohio and the coach is sitting in my driveway. I'll have to check and see which alternator I have.

I check and see about getting it rebuilt locally.

If I by a new one, I'd like it to be as plug and play as possible. I have 4 solar panels and am still using 3 AGM house batteries and 3 Optima start batteries. Had the Optimas load tested this fall and they seem to be fine.

Rich

Re: Alternator frozen

Reply #4 – May 15, 2025, 02:46:40 pm

Quote from: Chuck & Jeannie – May 15, 2025, 02:31:40 pm

If you plug into shore power, your inverter/charger should charge both battery banks (boost switch on) and the engine should run fine on just the batteries (no alternator).

Yes, assuming that your engine's water pump is still driven.

Re: Alternator frozen

Reply #5 – May 15, 2025, 03:17:58 pm

My records show it was replaced almost exactly 12 years ago.

Re: Alternator frozen

Reply #6 – May 15, 2025, 03:23:16 pm

See if there is a dealer who is authorized to rebuild them near you: Dealer locator – Prestolite Electric

We have a good one in Houston/Pasadena, but certainly not convenient for you.

Re: Alternator frozen

Reply #7 – May 15, 2025, 03:35:42 pm

Brett,

Thanks, nearest shop is over an hour away. There's a local shop that has been in business for almost 50 years. They seemed very knowledgeable when I called them. I think I may give them a try.

Rich

Re: Alternator frozen

Reply #8 – May 15, 2025, 03:36:53 pm

And, I haven't said it lately, but this forum is great! Thanks everyone, especially Michelle and Steve!

Rich

Re: Alternator frozen

Reply #9 – May 15, 2025, 04:20:16 pm

Just remember a rebuilt one is only as good as the parts they do not replace,I would go for a new Delco Remy 28si.

Re: Alternator frozen

Reply #10 – May 15, 2025, 08:48:28 pm

I take all of my alternators to a shop that have been in operation for probably at least 50 years. They understand duvac alternator which is what you should have. When you take it to them, make sure that you understand duvac alternators and you should be fine.

Re: Alternator frozen

Reply #11 – May 15, 2025, 08:49:17 pm

His existing alternator is 2012 with low hours on it. It's probably pretty good inside, and the bearings froze up. A shop will easily be able to put new bearings in for a reasonable price.

Re: Alternator frozen

Reply #12 – May 15, 2025, 09:03:00 pm

Your alt has an extra wire to put a small charge on house batteries well

Re: Alternator frozen

Reply #13 – May 16, 2025, 10:54:45 am

It probably it is rusted between the rotor and the stator. I have had that happen and took
the alternator apart and clean the rust and put it back together and it ran fine.

Re: Alternator frozen

Reply #14 – May 16, 2025, 03:40:10 pm

Followup report: I was able to remove the alternator yesterday afternoon. Took it in this morning to my local shop. They were very familiar with the design and plan to do a complete overhaul including new brushes, bearings, diodes, etc. Out the door price $299 + Tax. Should be ready Monday.

I like this approach because I can then reinstall it, just like it came out and don't need to worry about a different alternator with perhaps different brackets and electrical connections. I hope the reinstall should be pretty stupid proof.

The shop did say that they thought it might be rust between the rotor and the stator. Which can sometimes crack the case. Mine appears to show no damage.

Thanks for all the info and suggestions,

Rich

Re: Alternator frozen

Reply #15 – May 18, 2025, 12:39:17 pm

As a thought any mechanical component rusting up from non use indicates that it is being stored in a somewhat damp-humid environment with temperature changes causing condensation to form and rust damage to occur.

Other areas of concern include all the engine driven accessories including AC clutch and all the tensioners.
One thing folks don't think of is unlike a gas engine, there is no throttle. Except for the air filter there is nothing keeping air from moving in/out of the engine possibly causing corrosion at the tops of the cylinders, back of the valves, and the turbo assembly. Beyond the engine, the top of the rear axle ring gear, brake drums, rotors, pads, and shoes can also be damaged by corrosion. Point is that it is not a good practice to just lets these vehicles sit. and often more than just starting the engine is needed. The generators can also get damaged from sitting. Ideally, they should be started and driven maybe at least monthly.

Re: Alternator frozen

Reply #16 – May 23, 2025, 04:57:45 pm

Final Report on Alternator replacement

Got the rebuilt alternator installed today. Seems to run fine. Had to remove the two other belts to access the serpentine belt that drives the alternator so also replaced all belts. The hydraulic pump belt was starting to split down one outside rib. The owners manual specs a K080465 belt and that is what I took off. It was easy to remove and reinstall. When I tried a new belt, I was unable to get it over the pulleys.

I bought the coach from Mike O'Leary. He worked for Gates and gave me a belt he had custome built. It is a K08045.72 and it slips on easily. I'm running it while I figure how to get a K080465 on.

Any suggestions for getting it installed or should I just try a Gates K080471. It looks to be 3/4" longer. So I'm worried it may be too long.

Rich

Re: Alternator frozen

Reply #17 – May 23, 2025, 05:09:50 pm

Rich,

As I am sure you are aware belt length affects belt tension as different length belt rorates the belt tensioner to different degrees.

Too short= too much tension.

Too long= too loose.

Re: Alternator frozen

Reply #18 – May 23, 2025, 06:53:30 pm

Yes, as an old engineer, I know that proper belt length is important. But I have little practical experience. I'm sure that Mike O'Leary thought that a standard belt was too tight. From his old posts, he had a lot of practical knowledge about belts and tensioners from his job with Gates.

Rich

Re: Alternator frozen

Reply #19 – May 23, 2025, 08:21:18 pm

I agree.

And, as long as there is no belt slippage the less the tension the better. If any shininess to the belt and you need more tension.

Be aware than there IS another alternative for changing belt tension. You can drill a new detent hole in the bracket to rotate the tensioner a few degrees one way or the other. Been there, done that.

Re: Alternator frozen

Reply #20 – May 23, 2025, 08:42:59 pm

Quote from: Rich Bowman – May 23, 2025, 04:57:45 pm

......................
I bought the coach from Mike O'Leary. He worked for Gates and gave me a belt he had custome built. It is a K08045.72 and it slips on easily. I'm running it while I figure how to get a K080465 on.

Any suggestions for getting it installed or should I just try a Gates K080471. It looks to be 3/4" longer. So I'm worried it may be too long.
................

I seem to recall going through this fiasco as well, in which specified belts were not fitting correctly. I probably made a post about it several years ago with which belt PN I used. But I'm getting old, so I forget a lot lol

Edit: Guess I remember a bit: Try this post and thread: 8.3 Cummins, Water Pump/Alternator Squealing Belt

Also, I had bouncing tensionsers....turns out one of the pulleys was not mounted correctly and had a pretty large wobble: Part Number? Crank Pulley that drive hydraulic pump

Re: Alternator frozen

Reply #21 – May 23, 2025, 10:06:51 pm

I had the same issue with the correct Foretravel Part# belt not fitting after having the belt tensioner changed by NMS, the replaced tensioner was a Dayco and was the correct part number by cross reference, BUT after removing the tensioner and taking it with me to FOT and comparing all the measurements to the FT Cummins Original Tensioner there was only one difference the clocking pin was off on the Dayco compared to FT OEM Cummins tensioner, made all the difference in world.

Re: Alternator frozen

Reply #22 – May 24, 2025, 07:35:49 am

Quote from: krush – May 23, 2025, 08:42:59 pm

Also, I had bouncing tensionsers....turns out one of the pulleys was not mounted correctly and had a pretty large wobble: Part Number? Crank Pulley that drive hydraulic pump

I had the same issue-- crankshaft pulley driving the hydraulic pump not properly centered-- gave kind of an egg-shaped motion. The good news is that there was enough play in the pulley (mounting holes larger diameter than the bolts) that with half an hour of trial and error and using a piece of chalk to mark the high spot I got it centered.

Also, tensioners DO wear out. Watch this Gates Corp video: https://www.youtube.com/watch?v=h8pQT3YZAwo

Re: Alternator frozen

Reply #23 – May 24, 2025, 07:48:26 am

Quote from: Rich Bowman – May 15, 2025, 02:19:35 pm

Good afternoon for most of you,

Just tried to start the coach, getting ready for a trip in June. Last time I had it running was Nov.

It started right up but there was a serious squealing noise and when I opened the engine compartment, I found the main serpentine belt that drives the pulley for the A/C and the alternator broken.

I can turn all the pulleys except the crankshaft (no surprise) and the alternator. I assume I should be able to spin it by hand and that it is frozen. The alternator was replaced by FOT about 10 years ago.

Can you confirm that I should be able to spin the alternator? If so, It's time to start learning about alternators and sourcing a replacement.

I think I should be able to plug the coach back-in to a 30A circuit and then run the engine by turning on the boost switch. Is that also correct?

Thanks,

Rich

And should be able to do the same with generator running and boost switch on. But what else does the broken belt drive on your coach?

Edit: I see solution already found.

Re: Alternator frozen

Reply #24 – May 24, 2025, 08:57:39 am

Quote from: zmpm01 – May 23, 2025, 10:06:51 pm

I had the same issue with the correct Foretravel Part# belt not fitting after having the belt tensioner changed by NMS, the replaced tensioner was a Dayco and was the correct part number by cross reference, BUT after removing the tensioner and taking it with me to FOT and comparing all the measurements to the FT Cummins Original Tensioner there was only one difference the clocking pin was off on the Dayco compared to FT OEM Cummins tensioner, made all the difference in world.

You may have found the root cause of many of our problems! I'm not sure what tensionser I had installed (this was 10+ years ago). My RV has been in deep hibernation for the past many many years, but it's coming back to life.

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