Still having alternator issues

[DCatSea]

Probably continuing the ongoing annoying saga of my alternator - which I was blaming for weird tacho readings in a prior post. That issue seems to be resolved for now, after tightening up the v-belt, which, being new last year, was in need of a quick adjustment.

However, I am now having voltage / charging issues, which may or may not be related:
1) Batteries seem OK. I have tested them with a hydrometer and checked levels. They are holding 12v, so don't seem to be in trouble. Shore power charger is apparently doing its job.
2) Engine starts really well, and runs smoothly - no knocks, clanks, or other noises (touching wood as I write). No whining (or whinging) from engine or me.
3) BUT - only showing 11 - 12.4v on voltmeter when running at normal revs (1000 - 2700).
4) Interesting, and probably related - VHF shows "Low Battery" warning randomly. Annoying.

Anyone have any ideas on this. I am tempted to hand it over to the marina's mechanical team, but hate to not be fixing it myself. (Baking hot engine room has a LOT to do with this - will provide frosties to the mechs, who are all 30 years younger than me).

One more question: If i need to replace the alternator, where can i find one (for a 4D61), and do I need to replace the electronic tacho to match the new alternator?

Thanks for your inputs.


Doug

[hetek]

It's been a while since I had my 27FC, and much of the paperwork I acquired during ownership went with the boat, but I did find this:

"I purchased a new alternator from Spider Marine Electric (Prestolite/Leece Neville)."

I cannot recall much more, other than I had much the same problems as you and my local Marine Electric guy found the alternator to be partially shorted. He would get a shock touching the case while it was "alternating".

If you really get stuck, I can call Spider Marine and see if they can pull up my old order. Worked and fit perfectly but I think I had to make a slightly longer adjuster arm for some reason.

[RobS]

I would definitely start by installing one of these DVM's direct to the battery to be sure the voltage you are reading is indeed battery terminal voltage and 100% unrelated to some gremlins in your wiring, connections, busbar, terminal strips, gauges, etc etc.

Cheap and easy and will prove a useful tool even down the road when you get this all sorted out.

https://www.sbmar.com/articles/installi ... -dvm-boat/

https://www.sbmar.com/product/smx-digit ... e-monitor/

[Beta Don]

1) Batteries seem OK. I have tested them with a hydrometer and checked levels. They are holding 12v, so don't seem to be in trouble. Shore power charger is apparently doing its job.

A 12 volt battery which measures 12.0 volts only has a state of charge of about 40%. A fully charged battery should read 12.6 or 12.7 and if there's a float charger hooked to them, they should read 13.4 or so. So, if you have them hooked to a constant shore charger and are only reading 12.0, there's a problem there for sure. Your alternator problems may indeed just be the batteries. If they've sat for months and months at 12.0, they may be so sulphated that they won't accept a full charge

Don

[Sprig1]

Hi if you are still having problems try Pasco in Annapolis really good people. Very helpful and answer questions. They rebuilt two alternators for me. I think a little over 100.00 apiece. A lot better then $250.00 to $300.00 new. Or as Don has suggested before upgrade alternator and put on external voltage regulator. Not much different in price then buying new alternator. I decided I will put solar panels on first. Good luck

[Beta Don]

Why pay for a rebuilt when you can have a new one? Brand new marine alternators are dirt cheap!! - $50 to $100 or so, 100 amp, GM, Yanmar, even Prestolite replacements. One foot mount, two foot mounts, one wire hook up or 3 wire - Whatever works for your boat/engine. Do an eBay search for 'marine alternator' and you will find literally dozens of all types for less than $100, many with free shipping

I put a new 100 amp on my Yanmar and carried a second one as a spare on our Florida trip. If you do decide to upgrade to a higher amp unit, buy a quality belt and carry a couple spares. High power alternators tend to be hard on belts, especially if you don't check and readjust the belt tension every 10 or 20 hours

Don

[DCatSea]

Excellent advice - par for the course on AOG. Thanks to all who responded. Makes me feel better that this isn't a life changer.

I may replace the older model charger as well, and have been reading a lot about Pulse Tech Desulphation technology, which apparently / people say works well as a sulphation preventer.
Has anyone had experience of this "battery saver", and can anyone say if it works to rehab younger batteries that may be suphated. Mine are still under warranty (limited, I guess).

[Bearkeley]

Brian at American Diesel can send you the right alternator... pretty simple install....after you figure out the wiring. We had the same problem and with solar on the boat, didn’t realize our alternator was practically dead until we got to South Carolina (started at the MD /VA line!).

[DCatSea]

Hi guys

Alternator definitely quite sick. I spoke with Brian at AD, and he was very helpful. However, he did tell me that the OEM Motorola was "very rebuildable" so I ended up taking it out and running it up to Steve at Maryland Transmissions in Churchton. They did a great rebuild on my Hurth transmission, and apparently do an equally good job of alternators. Took it in yesterday PM and hope to be reinstalling Tuesday at the latest. Sure it is an easy enough reinstall, and I won't have to recalibrate the tacho. (Also easy enough but a pain to do, so I'm told)

I'll let you know how it all works out.

[DCatSea]

OK - probably fixed it Reinstalled the rebuilt Motorola, new belt - instant relief. Thought to put in a new - updated - charger with monitoring, and took the opportunity to rip out all the old shore power cables (and PO's leavings) and replace them, plus a couple of new shore sockets. Repositioned battery switch and 110v panel to accommodate the new resized charger.

Also acted as witness to a probable BWI incident involving damage, and assisted in the landing of a new marina member who was ejected from the back of the boat at the slip.

Busy 2 days - ended with a 30-minute kayak trip because I wasn't tired enough. Happy days. Stayed awake to drive home.