1976 Ski Nautique PCM 351 not charging
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=37155
Printed Date: October-05-2024 at 6:42pm
Topic: 1976 Ski Nautique PCM 351 not charging
Posted By: sberard5
Subject: 1976 Ski Nautique PCM 351 not charging
Date Posted: August-23-2015 at 5:36pm
Been using my 76 Ski Nautique all summer without a single problem. Last weekend, was out for a swim and went to start engine and it turned over really slow and did not start. Had to borrow friends jump pack to get us home. Its got a 351w PCM with prestolite alternator.
When I got back to the dock, left it running to test with multimeter. 11.5 volts at the battery so alternator not charging. Took alternator off and brought to my local alternator shop. He bench tested successfully and said more than likely my voltage regulator was the problem. So, purchased a NOS ARCO VR-406 voltage regulator online. Installed it yesterday along with the alternator I just had tested. With a freshly charged battery, fired up the engine and still no charging. Left my multimeter hooked to the battery and took it for a ride. Load tested alternator @3000rpm with lights and blower running and just watched the voltage slowly dissipate. Got back to dock and removed alternator to do a diode test which was successful. I have checked the ground and all wiring between regulator and alternator. All look great. For some reason alternator is not putting load on motor. Is it not excited?
I am fairly well rounded mechanically but electrical troubleshooting is my weakness. I am stumped on what to do next???? I am thinking my prestolite alternator is bad. Does anyone know whats going on here? Anyone have any other troubleshooting ideas? Any other tests I can do? Thanks in advance for your help.
Steve
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Posted By: sberard5
Date Posted: September-02-2015 at 2:41pm
Ok so there aren't too many people who answer their own posts but I am because there's the possibility this may help someone with a similar problem. My problem ended up being a broken solder joint where the field wire is soldered to the stud that protrudes through the rear case of the alternator. More than likely, when the previous owner removed the alternator, they didn't apply counter torque when loosening the nut on the field terminal stud causing the solder joint to eventually weaken and let go. What was happening was when I hit waves it would make and break contact causing an intermittent charging condition. The fix was to resolder the field wire to the stud inside the alternator. I reassembled alternator and tested SAT. Also, found out boat had the incorrect voltage regulator, wasn't a voltage regulator but a cut out switch. Replaced with original type ARCO VR-406 voltage regulator. Purple wire to inlet side of ballast resistor, plug to plug and negative ground. Boat now charging properly.
For anyone who has this problem and wants to just replace 3 wire Prestolite alternator with the newer style 1 wire alternator, just watch out. Some of the cheaper 1 wire alternators are made in China, claim to be marine but aren't. I stuck with the Prestolite because it is ruggedly built and looks like new after 39 years of use with little service.
Hope this helps anyone with charging issues...
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