Guest minkos Posted August 2, 2011 Share Posted August 2, 2011 pretty dramatic, as the title suggests. one day while the engine was warming up, i looked under the hood of my '66 401 and saw smoke coming from the underside of the voltage regulator. seeing that the underside of the regulator (which is the original unit) was a bit greasy and cruddy, i removed it and cleaned it carefully, then reinstalled it. same thing, within about 30 seconds of starting the engine the smoke starts coming out. it looks like it is coming from the long thin cylindrical connector on the bottom side of the regulator closest to the 4-prong modular plug. as near as i can tell, that connector joins the "F" and the "4" terminals. the GEN light operates normally (on when starting car, off when car starts). the regulator cover is cool to the touch when all of this is going on. i removed the cover and nothing looks burnt or melted.i have the NOS replacement regulator but am reluctant to install it until i understand more about what is going on. i read the shop manual a few times over and i was going to run the suggested alternator and regulator tests, for which i will need an ammeter. any suggestions on ammeters or why the regulator is smoking? whatever it is, it can't be too good.thanksMark BCA 14421 Link to comment Share on other sites More sharing options...
Guest rsd9699 Posted August 2, 2011 Share Posted August 2, 2011 Best have the alternator stress checked - one of the diodes in the alternator is weak and will likely short out and cause wiring problems or/and engine compartment fire.If alternator okay - then a short in the connecting wiring or the points stuck in the regulator itself.Ron Link to comment Share on other sites More sharing options...
RU22 Posted August 2, 2011 Share Posted August 2, 2011 Don't know about Buicks but in Lucas equipped cars it has been know for years that all these electrical items contain and are opperated by smokeIf the part cracks it lets the smoke escape and the unit without it's required smoke fails ..........I think this was first discovered by the guy that designed the cargo door on the DC-10 Link to comment Share on other sites More sharing options...
Bhigdog Posted August 2, 2011 Share Posted August 2, 2011 The long "connector" is actually a wire wound resister. Wire wounds are usually designed to operate hot. I'm not sure just how hot they normally get but it's possible you are just seeing oil or grease, which is NOT supposed to be there, burning off the resister..........Bob Link to comment Share on other sites More sharing options...
startergenrebuilder Posted August 3, 2011 Share Posted August 3, 2011 Mark,It is pretty common for a new regulator (resistor) or one that has sat for a long period of time to smoke when being used for the first time. It should pass after a few minutes.JasonAdvanced Electrical Rebuilderswww.aerrebuild.com Link to comment Share on other sites More sharing options...
Guest rsd9699 Posted August 3, 2011 Share Posted August 3, 2011 The fire test is always the most scary test - keep a fire extinguisher handy.Ron Link to comment Share on other sites More sharing options...
Guest minkos Posted August 3, 2011 Share Posted August 3, 2011 well spoken ron. quite frankly, i'm afraid to let it smoke too long. i understand that it is the job of a resistor to get hot, but i am worried that i will irreparably fry something, not to mention set the car on fire. the alternator and regulator are original to the car. i've owned the car for almost 30 years and the regulator never smoked after sitting for awhile. the car had only been sitting for about 2 weeks when i first noticed the smoking. what i did notice that first time was a fine mist of oil on the fender well surrounding the regulator. i don't know how it got there, i normally keep the fender wells wiped down and fairly clean. i cleaned the regulator and the resistors pretty well to rule out the oil but the smoking continued.i ran a voltage test on the system today. at idle speed in park (around 700 rpm) at startup with the high beams on the voltmeter across the battery read 12.8V, kind of low. but when i reved the engine up to 1500 rpm and held it there, the voltage increased to around 14.5V and stayed there. i reved it up a little more, and it still stayed at 14.5V. when i let off the throttle and back to idle, the voltage pretty much stayed at 14.5V. on cue, the resistor started smoking, and it seemed that it smoked more after i switched the engine off. again, the GEN light works as normal (off after startup).any further theories are greatly appreciated.MarkBCA 14421 Link to comment Share on other sites More sharing options...
Guest minkos Posted August 3, 2011 Share Posted August 3, 2011 (edited) after thinking about this some more, and with the fire extinguisher ready, i decided to try jason's suggestion. while the resistor smoked away, i checked the generating circuit wires and modular plugs for excessive heat-none. after about 10 minutes, the smoking subsided completely. i'll be carrying the extinguisher around in the trunk for the foreseeable future just in case.thanks jason and bob for the good call.Mark BCA 14421 Edited August 3, 2011 by minkos (see edit history) Link to comment Share on other sites More sharing options...
RU22 Posted August 3, 2011 Share Posted August 3, 2011 Mark Please keep the fire bottle close to you!!!!You may not have time to deal with unlocking the trunk and opening the hood Link to comment Share on other sites More sharing options...
NTX5467 Posted August 3, 2011 Share Posted August 3, 2011 Keeping the extinguisher in the passenger compartment might be a good idea, just in case the olefactory sensors don't go off prior to the visual sensors going off. Hopefully, you'll be in a place where the car can be curbed successfully before applying the flame retardant coating as necessary.Regards,NTX5467 Link to comment Share on other sites More sharing options...
Guest rsd9699 Posted August 4, 2011 Share Posted August 4, 2011 I hope you have a shop manual.I repeat - take the alt and reg to a alternator repair shop and stress test it. An auto parts box store can barely spell the word and they can not stress test it.Post pictures of the underside of the reg. Pop the two screws on the reg cover and take more pictures. Use fingernail to see if points are stuck. Points pit quickly and make the face of the moon seem smooth. Two or three light strokes on each point is what they use to do to "rebuild" these old regs.The one coils' windings should be shiny and copper colored - if dark or burn the reg has seen its better days, get a replacement and use the old cover and screws to retain the original look. A little vinegar on the cad plating on the base will help age that part as well.Have the alt shop replace the front bearing, new brushes, wipe the grease from the rear shaft and needle bearing and re-grease. Do not let them do anything cleaning with chemicals - you now have a newly rebuilt alternator that looks old.Ron Link to comment Share on other sites More sharing options...
Guest minkos Posted August 8, 2011 Share Posted August 8, 2011 i do have a shop manual. i read the charging circuit section several times over before doing anything.today i took the alt and the reg to a recommended alternator repair shop to have both components tested. they both checked out ok.i will post pictures of the underside and inside of the reg once i can resize the files.Mark BCA 14421 Link to comment Share on other sites More sharing options...
JohnD1956 Posted August 9, 2011 Share Posted August 9, 2011 the alternator and regulator are original to the car. i've owned the car for almost 30 years and the regulator never smoked after sitting for awhile. the car had only been sitting for about 2 weeks when i first noticed the smoking. what i did notice that first time was a fine mist of oil on the fender well surrounding the regulator. i don't know how it got there, MarkBCA 14421This is interesting. I wonder where the oil came from? Was it just around the regulator? or much wider than that? In guessing at a source, I wonder if this mist of oil could be brake fluid? Link to comment Share on other sites More sharing options...
Guest rsd9699 Posted August 9, 2011 Share Posted August 9, 2011 Depending on how often you drive the car - the only 4 places are from the a/c compressor, the PS pump, the fan clutch, or the crank shaft pulley.Or maybe the little elf that you have crawling under the car doing all your dirty work....... Link to comment Share on other sites More sharing options...
Guest minkos Posted August 9, 2011 Share Posted August 9, 2011 here are the pictures. the smoking resistor was the upper one. on the inside, the tape is still on the windings and i didn't want to disturb them.since the car is non A/C and the brake fluid reservoir was full and wasn't oily, the likely suspect is the power steering pump.and since i am that elf, i know it wasn't me!Mark BCA 14421 Link to comment Share on other sites More sharing options...
startergenrebuilder Posted August 9, 2011 Share Posted August 9, 2011 Mark,The oil would definitely explain the smoking from the resistor. Most people don't realize how hot those puppies get. They (me too quite a few times) usually find out when they accidentally touch one when working on something nearby. I've grabbed many while working on them on the test bench, you know it right away! They are just mini-toasters! Anyway, I thought everything visible in the pictures looked okay.JasonAdvanced Electrical RebuildersAdvanced Electrical Rebuilders - Antique Auto - Marine - Agricultural - Industrial Link to comment Share on other sites More sharing options...
JohnD1956 Posted August 10, 2011 Share Posted August 10, 2011 Yes, wasn't thinking about it too clearly last night but maybe a leak in the power steering hose? Link to comment Share on other sites More sharing options...
Guest rsd9699 Posted August 10, 2011 Share Posted August 10, 2011 You may check the resistors where they are clamped to see if they are loose and causing excess heating. The coils look fine as the paper would have discolored if there was a problem there.Ron Link to comment Share on other sites More sharing options...
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