WHY? Alternator is burning hot… too hot to touch! 1993 coupe

Everything was fine with my el-cheepo 4 banger silver notch, until… on my commute home I smelled what seemed like burning electronics, this was just up my street, so I pulled into my driveway and quickly opened the hood, extinguisher at the ready. Couldn’t find a damn thing wrong. Was looking around and happened to place my hand on the alt housing to brace myself as I peered ever deeper into the engine bay. Hot enough to burn and the smell came from the housing… no smoke

Let it sit overnight, started up again, and less than 1 minute the alt housing was TOO HOT to touch. I mean really hot… I took the belt off and it spun freely and spun smooth. It seems to be charging fine, just as usual, which seems a little high on the gauge compared to my experience with other Fox’s. I know that gauges are est. only and vary from car to car… hmm I checked my grounds out too and they are tight and firm.

Any ideas? I have to drive the chevy truck (1 ton gas PIG) until I figure it out and I’m not convinced that I need to buy a new alternator? hmm

Any hints allegations heresay postulations speculations, arguements, anyone

Standard, Alt is going bad. I had one do the same on my Powerstroke.

Just FYI, dont buy a rebuilt, they usually have a similar issue. I had very good luck with Autozones Paladin (new) line instead of rebuilt

Another thing is, charge the battery fully with a battery charger, if the battery is dead it'll put out max amps and cook itself

Originally Posted by 67fastback

Any hints allegations heresay postulations speculations, arguements, anyone

Check your alternator connector. I've heard that if the spade connector has corrosion, it sets up a barrier (resistance) which causes heat to build up. If that is the case, you should be able to find a replacement connector at the auto supply store...you might be able to test if that is the problem by using emery cloth (any fine abrasive) to polish the surface.

I double support cleaning all the alt connections and test the heat issue again...

Then just replace it if it still get's hot. Reman will work, and if you get a bad one another is only a trip to the parts store away... Likely $40 bucks less than new...


FE

will check that, thanks all
btw
bought a new alt from ford for my 1991, put about 10 miles on it (before storing that car away) will use if cleaning/replacing connectors dont help on 4 banger unit, thanks again

The connectors were completely PACKED with dielectric grease, just jammed with the stuff. I used CRC's QD electronic cleaner and air compressor to remove the junk and clean the connectors. The alt heated up in about 35 seconds. I mean its amazing just how quick the darn thing heats up, there is a powerful action involved. I removed the new Ford Alt from my 1991, changed clock position and installed it. Seems fine now. I just wonder what the failure mode is? I would really like to know...

The diodes in your alternator are shorted out and holding the charge you are making when the engine is running, this causes the heat because they are unable to discharge the energy they are storing.

Exactly my thoughts.. I used to work on the local community transit jitney buses both diesel and gas but they used 200 amp alternators and ive seen this issue alot.

Cheapo REMAN is not a good option in this case, normal answer is they are decent, however for some reason these modern Ford alternators will pass output voltage and amperage and the diode no-go test but still burn up. However a real alternator specialist may do better. The normal ones just test components and the diode set is a bear on these alternators.

One I had actually started smoking on my own truck and I saw it pass all the tests.

I had a typo above, the Paladins are from Advance Auto (Kragen) not Autzone, and are the new pieces, prices are within 50 bucks.-

One last thing, new Fords NEED a fully charged battery before you fire it up, the alternator will go full charge and cook itself if you try to replace it and just fire it up. Put the batt on slow charge the day prior