Completely seized alternator!

[KWKloeber]

Guys : Look in the Mainsheet tech notes !! 

I wrote a couple of articles one of which covers some of what Ken has mentioned.  There is a formula of how and what to set the dip switch setting at on your Teleflex engine tach instrument.  This formula compensates for a different number of stator poles and a different size pulley!!

A few thoughts

Here's an explanation taking it through the reason how the alternator construction affects the tach reading.
https://groups.io/g/Catalina30/message/112386

The Teleflex gauge troubleshooting guide that I had posed on the TechWiki site describes the switch settings to use for each type of alternator.  Other manufacturers will likely have different switch settings, so check the literature/calibration instructions (or try settings trial/error.)
       

[Sailing Amok]

Thanks for all the info and suggestions everyone. I was able to find essentially the same alternator as what I'd taken off, at a local shop. Based on the discussion here, I decided that was the logical way to go for now, with an upgrade to a larger, externally regulated alt in the near future. This one will become the backup. Interestingly, this new Mando claims 55 amps, while the old one claimed 50 amps. Other than that the only difference appears to be that they changed the tension bolt from a 1/2 inch to metric, which I only figured out after attempting to install it. Always another trip to the store! Anyway, got it installed a couple weeks ago, but due to other life issues was only able to go out for a little motor around the harbour after installation, and haven't been able to go sailing all month.
I had hoped that the weird hissing sound the engine developed over the past couple seasons was the early warning of the alternator failing, unfortunately that does not seem to be the case, as the hissing remains. I'll start a new thread about the hissing, with a video I took this week. Other than that, we're planning to head out cruising for the weekend, so fingers crossed the engine behaves, or even better, the winds behave and we don't need the engine! For a couple who are normally on the hook every weekend of the summer, this has been a rough month...

[Breakin Away]

Thanks for all the info and suggestions everyone. I was able to find essentially the same alternator as what I'd taken off, at a local shop. Based on the discussion here, I decided that was the logical way to go for now, with an upgrade to a larger, externally regulated alt in the near future. This one will become the backup. Interestingly, this new Mando claims 55 amps, while the old one claimed 50 amps...

Could you post the model number? It might be handy to know if my alternator should fail in the future. Drop-in replacements are always good to know about.

[Sailing Amok]

Could you post the model number? It might be handy to know if my alternator should fail in the future. Drop-in replacements are always good to know about.
[/quote]

It's a Wilson Reman 90-31-7001

[KWKloeber]

Excellent choice Aaron !!!

If I had to stake my life on an Alt, it would be a Wilson reman.  They are better than an OEM Mando because 100% of them are tested before they go on their shelf for sale. 
Also, Wilson can tell you the voltage set point of each so you can pick the one that has the regulator set to the closest that you want.

Wilson even sells a new SAEJ1171 (the Mando number) as WILSON 90-31-7000N.

A good place to check for Wilsons for our engines (Alts and Starters) is www.FiltersPro.com 
Tracy is a great guy and a disabled Vet.  The only thing is that you need to know exactly what you want -- it's not an "alternator shop" that has experience mixing and matching alts for oddball applications/marine engines.

[Sailing Amok]

Also, Wilson can tell you the voltage set point of each so you can pick the one that has the regulator set to the closest that you want.

Ken, I'd chosen to go that route because of your previous praise for the Wilson remans on other threads here.  I didn't realise that they could tell me the voltage set point . Are they able to tell that from the serial number? Like, would I be able to contact them with the serial number of the one I purchased and find out the set point? Obviously too late to do anything about it, but I'd be curious to know.

[KWKloeber]

, Aaron

Possibly, but in the box w/ the reman there should have been a Test Report.   Where did you buy it? 

Wilson (BBB) gave me the V set of the 4 or 5 units they had on the shelves @ different nationwide locations.
Email BBB and see if they maintain the test results in a database.

The contact I last had there who gave me the Vs was
Jerry Davis
jdavis@bbbind.com
Who knows if he's still there --- if not try the BBB webmail form
https://www.bbb-cv.com/en/contact

Here's your Alt page:
https://www.bbb-cv.com/wilson/en/90-31-7000/product/90-31-7000

Let us know!