How to disconnect the Air Inlet Heater on a 2001 Cat 3126 engine

Dani-Lu

Well-Known Member
Apr 20, 2007
1,352
Delray Beach, Fl
Boat Info
2001 410DA
Engines
3126 Cats
We are trying to isolate an alternator problem and we want to disconnect the Air Inlet Heater to ensure it is not causing the Alternator to not charge above 12V. I believe there is a solenoid in the junction box, but I want to make sure I am disconnecting the right wires. Or can I unplug the wire from the solenoid on top of the engine?

Thanks,

Jeff
 
Jeff,

I'm not sure how the intake heaters can limit the alternator output. If the alternator won't output 13.5VDC, I suspect an internal issue with the alternator. Cat alternators need some rpms top achieve the rated output, so if you are checking this in your slip at idle, you may need to run the rpms up to about 1200 rpm and check the output with a voltmeter at the alternator. Next, pull the alternator off and take it to an auto-electric repair shop and have it tested.....I'm betting the internal regulator is bad.

If you need alternators, Prestolite (Leece Neville) is a Cat OEM supplier and has a direct replcement for about $275.
 
Frank,

That's what I said to the mechanic. He admits he is not a diesel guy. I only use these guys for winter storage, shrink wrapping, winterizing and change impellers on both engines and spring launch. Yesterday I told him to pull the alternator and bring to shop. My port alternator went last season. Now the starboard one. If/when I sell this boat, someone will be getting a great boat, with many new/rebuilt parts. I guess it's expected on a 16 year old boat.

Thanks,

Jeff
 
My alternators made it 19 years........I have no complaints considering the Cummins boats all around me are getting 18 months out of OEM and factory remans.
 
I run my generator most of the time away from the dock. Should I shut off the AC Coverter/Charger when running the boat or do the alternators take over charging the batteries and the AC Converter isn't doing anything, whether it is on or off?
 
I don't think it matters because the convertor only supplies what the battery voltage tell it to supply. If your batteries are fully charged, the convertor is putting out 0 volts.

However, the new alternators I sent you the link for are 95 amp alternators where the OEM ones were 56 amps. Since changing to the new alternators, I only run the convertor when the engines are off.
 
Mr Webster is right on target. Remember also that the Leese-Neville have a output voltage adjustment that must be set when installed. I set mine at 14.3 volts. If there is a very high current draw on the alternator then the voltage output will droop; a resistance heater can cause this but if the system was originally designed for this configuration I agree, it appears one or more of the rectifiers are going south....
 

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