I have a dead alternator, and since these are completely uncharted waters for me, I thought I would bring a couple questions up tot he group. Would having my alternator rebuilt be a practical solution, or would it be best to buy new? If a rebuild would be the most cost effective, is this something I could have done at a shop that sepcialized in diesel engines, or do I have to pay the premium to have a yard do the work? How much could I expect to pay for a rebuild, and how much (ballpark) might a new one run me?
As always, thanks for the help!
Adam
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Tobaygo
1987 Catalina 36 MKI
#660
Tampa Bay, FL
Avoid marine shops for your alternator. Take it to an automotive store. They have the same guts. Save lotsa $$. What killed your alternator? How do you knwo it's dead?
Stu Jackson, C34IA Secretary, C34 #224, 1986, SR/FK, M25 engine, Rocna 10 (22#)
What Stu said. And when you go to the auto shop, don't tell them it's off a boat, just give it to them. If you say "boat" the price will rise greatly. No rocket science going on inside the case anyway.
But to answer your question, had the Prestolite alternator on our C28 rebuilt at an auto shop and all was fine until I said "boat". Price then became $190 Cdn. Another shop where I didn't say "boat" did it for $90 Cdn. I can buy a new 90 amp Prestolite for $205 Cdn so $190 for a rebuild was kinda outrageous.
I love the "boat" surcharge. What a PITA! Thanks for the tips, looks like a trip to the shop for me.
Stu-
The alternator has been dead since I bought the boat, and I can only assume that the PO or one of his guests moved the battery bank switch to the off position while the engine was running. The tachometer usually reads 0 RPM, and I have never noticed a charge on the batteries with the engine running. I used a volt meter to test the output on the back of the alternator and got no reading, and then tested the battery voltage and they all read 12.38 indicating no charge. Granted I am not electronically inclined, but I assume this indicates a dead alternator. Thoughts?
Thanks again!
Tobaygo
1987 Catalina 36 MKI
#660
Tampa Bay, FL
It could be just that the diode pack blew, that effectively kills the output. An alternator shop will be able to tell you that right away and that's not an expensive fix. Worth taking it in and finding out for certain.
[QUOTE=akorinek;4121]
The alternator has been dead since I bought the boat, and I can only assume that the PO or one of his guests moved the battery bank switch to the off position while the engine was running. The tachometer usually reads 0 RPM, and I have never noticed a charge on the batteries with the engine running. I used a volt meter to test the output on the back of the alternator and got no reading, and then tested the battery voltage and they all read 12.38 indicating no charge. Granted I am not electronically inclined, but I assume this indicates a dead alternator. Thoughts? [/QUOTE]
Now we understand, classic symptoms, and reasonable assumptions (those darned POs!:)).
If it was my boat, I'd take it into an automotive place and have them repair it. It's pretty important to have the alternator charge your bank(s).
Make sure you label each and every wire when you take it off, make a sketch and/or take photos.
Stu Jackson, C34IA Secretary, C34 #224, 1986, SR/FK, M25 engine, Rocna 10 (22#)
Did you check the input voltage at the alternator, you should read 12 volts or battery voltage at the F or field terminal with the ignition switch on. The alternator will not put out if there is no controling voltage going to it.
Broken wires around the alternator due to vibration are common.
Cepheus dream
C36 MK I # 825
MK I Tech Editor No Mas
Okay, I'm now at a point where I am going to have to reveal my ignorance! There are only 2 wires attached to the backside of this thing. One is the large guage wire to the batteries, and I assume the other (labeled P) is tach output? I do know it is internally regulated.
Any thoughts? I do appreciate all of the experienced advice!
Tobaygo
1987 Catalina 36 MKI
#660
Tampa Bay, FL
Adam,
I was hopeing to fined a wiring diagram on our Tech CD for you boat but did not see it.
I do not have full recall regarding the wire locations on the alternator but,
you have not found them all or are missing some. You are correct about the heavy wire that will be the output to the batteries. There is also a wire for the tach. But the way the voltage regulator controls output of the alternator is by varying the voltage to the field terminal of the alternator. The field wire will if the regulator is functioning properly will read battery voltage when you switch the ignition on. You will read battery voltage on the large terminal of the alternator any time you battery switch is turned on. The tach lead as I recall only looks for pulses as the alternator rotates and I do not believe it will read any voltage. There should also be a ground lead going to the case of the alternator.
You need to find and trace out more of the wiring
Cepheus dream
C36 MK I # 825
MK I Tech Editor No Mas
Thanks Steve. I'm heading down this evening so that will give me something to do. I'll try and send a mobile update if/when I find anything.
Tobaygo
1987 Catalina 36 MKI
#660
Tampa Bay, FL
Try this: [url]http://c34.org/bbs/index.php/topic,5473.0.html[/url]
Stu Jackson, C34IA Secretary, C34 #224, 1986, SR/FK, M25 engine, Rocna 10 (22#)
Thanks Stu for the link. Based on a linked document in there it looks like I have a Delco-style alternator, and I have found some with only two wires. I am going to get on the boat after work today and start looking around for loose wires. Until then the mystery continues...
Might it be a self-exciting alternator? From what I have read they only require the output wiring to the batteries to operate.
I love boats, but I HATE mechanical stuff. As a pilot, my job has always been to break mechanical systems!
Tobaygo
1987 Catalina 36 MKI
#660
Tampa Bay, FL
It's quite possible that's what it is, there are some delco style alternators that are one wire only. It could be an aftermarket unit and not the normal Prestolite one.
I am pulling my hair out over this one. So far I have determined it is a Delco Remy 1-wire alternator. It is the standard 10-si set up which comes in a 1 or 3 wire configuration.
Apparently, the 1 wire version is typically installed on engines that operate with higher rpms as they have to hit slightly above 2000 rpm to begin charging. Of course, I found this out after installing the new unit and beating my head on a wall for an hour trying to make it work. I'm going to head up to the boat one day this week to see if I can rev the engine high enough to get it to begin charging. Fingers crossed.
Tobaygo
1987 Catalina 36 MKI
#660
Tampa Bay, FL
Keep in mind that alternator speed is usually much higher than engine crankshaft speed due to the different diameters of the sheaves (or pulleys). It would be surprising that an alternator installation would not be able to put out useful current at an engine speed of only 1200 RPMs or so.
Duane Ising - Past Commodore (2011-2012)
s/v Diva Di
1999 Catalina 36 Hull #1777
Std rig; wing keel, M35B, Delta (45#)
Punta Gorda, FL
http://www.sailblogs.com/member/diva-di/
I think it's a question of getting the rpms up enough to trigger the regulator into starting a charge. From there it can then produce a charge at reduced rpms. From what I've read you used to have to rev up a car engine for that same reason. I'm starting to wonder if I can get the rpms up that high to trigger it. We'll see tomorrow if I can make it down.
Tobaygo
1987 Catalina 36 MKI
#660
Tampa Bay, FL