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Discussion Topic:
'39 Merc starter button R&R
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flatcreeker |
10-24-2021 @ 3:23 PM
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Member
Posts: 48
Joined: Feb 2021
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I'm an idiot. I retraced my steps with continuity check. Thought I had the auditory alarm "on" but I had it "off". I DO HAVE CONTINUITY but no voltage between generator case and ground and likewise with regulator base. You have been most patient TomO. I will join one of the local chapters. Been trying to decide which one. None are proximate and I don't do Atlanta. Best to you- Doug
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TomO |
10-24-2021 @ 9:26 AM
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Senior
Posts: 7243
Joined: Oct 2009
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I am having a problem understanding your post. You said that there was no voltage between the generator case or the regulator mounting and the POS post of the battery. Then you go on to say that there was no continuity between them. If you have a good grounding the case of the generator and the mounting base for the regulator should show continuity to the POS post of the battery. My instincts tell me that you equipment was not functioning properly or the grounding cable from the battery to the firewall is open. At this point, I feel that you should get some local help. Please contact the Regional Group nearest you for assistance in finding a good electrical shop to help you. You can find the contact information in the Regional Group Directory on the left side of this site.
Tom
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flatcreeker |
10-23-2021 @ 2:04 PM
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Member
Posts: 48
Joined: Feb 2021
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Greetings- I accomplished the checks between generator case and + batt terminal, and between regulator mounting and + batt terminal. Checks revealed no voltage present, not even continuity indicated. Generator was putting out 8.1v and climbing at time of checks. Returned to 6.4v at idle (at battery). I have a continuity tester which resembles the typical ice-pick with light-in-handle and wire lead with clip. Only this one has a digital display in handle and matches accuracy of my digital multimeter and vintage analog volt meter. It also indicates polarity: green light = pos ground, red light = neg ground. Can I use this to determine polarity of generator and avoid the polarizing process (if pos grnd is indicated) and if so, how do I connect? Volt check at battery indicated initial cut-in was slow to occurr, requiring 2-3 minutes at 1000+ rpm before voltage at battery rose above 6.4v. Then cks described above were accomplished. Battery + grounded to firewall via a short flat braided strap and block grounded to firewall by flat braided strap. All ground connections under the hood have been cleaned and in some cases star washers added.
This message was edited by flatcreeker on 10-24-21 @ 8:21 AM
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TomO |
10-22-2021 @ 10:43 AM
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Senior
Posts: 7243
Joined: Oct 2009
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Your problem still sounds like a bad ground. Connect your voltmeter COM lead to the generator case and the + lead of the battery post, not the cable connection, while the engine is running at about 1,000 rpm. The meter should read less than 0.1V. If that is OK, do the same to the regulator mounting base. If either of them read higher than 0.1V you have a grounding problem. Do not run the engine for a long period of time as you could damage the regulator or generator. If I remember correctly you should have a grounding cable from the battery to the firewall and another from the firewall to the engine,probably a head bolt.
Tom
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TomO |
10-22-2021 @ 8:20 AM
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Senior
Posts: 7243
Joined: Oct 2009
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There are 3 Regional Groups in GA, contact one of them for help with your problem. You should be able to get a reference for a good electrical shop from one of them. Do not drive the car with the generator connected, you may do more damage.
Tom
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flatcreeker |
10-22-2021 @ 7:17 AM
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Member
Posts: 48
Joined: Feb 2021
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Also- I am trying to identify my generator by PN. Based on pulley size (3 3/32" OD measured at forward flange and 4.0" measured at fan), which, of course could have been changed, and also photo similarity and height measurement of the mounting bracket/front end plate, it is not original to a 1939 Mercury. Maybe 21A 10000, a PN indicated by several manuals as the replacement for the 91A 10000.
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flatcreeker |
10-21-2021 @ 10:48 AM
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Member
Posts: 48
Joined: Feb 2021
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Things related to generator/regulator continue to be all over the place. Readings at battery range from 6.3v at 1250 rpm to 8.6v (and still climbing) then returning to 6.4v at idle. Sometimes the voltage increases in a textbook manner as rpm pass the expected cut-out threshold and sometimes not until 1400 rpm. The only consistent seems to be the return to 6.4v as rpm return down to idle. No adjustments have been made to this 3rd regulator. Yesterday, during a short 4 mile test drive, the dash gauge indicated an overcharging condition. I pulled over and ck'd voltage at battery: 8.1v at 1400 rpm. I returned home keeping engine rpm as low as possible and coasting at idle much of the time. Once home, I raised hood and went through the process. 6.4v at idle, steady at 7.5v at 1400, then after about 2 minutes it started steadily climbing to 8+ v at 1400. This seems to indicate that the regulator "can" function properly. Makes me think the generator has something hinky going on. I am weary of trying to do it myself and my confidence in my generator shop is waning. Going to a big car show/swap meet on Saturday (regrettably not in the Merc) and hope to get a lead on a shop to take it to for generator rebuild and new regulator install and check-out on vehicle.
This message was edited by flatcreeker on 10-22-21 @ 7:00 AM
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TomO |
10-15-2021 @ 8:37 AM
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Senior
Posts: 7243
Joined: Oct 2009
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I have been using a Klein Tools Electrical Tester that I bought at Home Depot for doing electrical work around the house for the past 9 years and have been happy with it. I find little use for an ammeter in maintaining my old cars. A good analog multi-meter is useful. Most of the time I use the analog meter on my automotive test set that includes a dwell meter and tachometer. I have used the Fluke meters in the past and they are very good. Both the Arm and Field terminals will read continuity to ground. See attached photo. Max current on your generator should be 30 Amps, if the generator has not been modified to 40 amps. Make sure that the generator and voltage regulator are grounded. Again, the voltage regulator should not need any adjustment. Have your generator tested again by the generator shop, then install it and the new regulator at the same time. Polarize the generator by touching the field wire to the BAT terminal of the voltage regulator. Then check that the generator and voltage regulator have good grounds. Now you should be good to go.
Tom
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flatcreeker |
10-14-2021 @ 9:40 AM
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Member
Posts: 48
Joined: Feb 2021
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Back at the cabin and the Merc. I'm glad to see it didn't run off. My guy didn't make any adjustments to the new regulator he installed. I remove the battery grnd cable every time before working on/removing/installing anything electrical. There is no contact between resistors under regulator and firewall. I ordered a regulator from 3rd Gen, only specifying '39 Merc. Hope to have tomorrow or Saturday. I have continuity between the generator case and field terminal on generator. Same with case and terminal on back of generator. Same between field terminal and terminal on back of generator Is that as it should be? Seems a bit incestuous. I understand voltage at battery when charging by generator should max at between 7.2V-7.5V. What should be max current? Should I test for max current with lights and accessories on or off? I want a multimeter with clamp type ammeter. Could you recommend one? Absent advice to the contrary, I'll go with a Fluke. I know I'm likely looking at $100-300. I'm ok with that as I don't see tool costs as frivolous. Are there any analog induction ammeters out there? The only analog ammeters I see require an in-line device. Thanks again for your counsel. I am learning, but d*mn it seems slow. You know you could save me a lot of time if you came and spent a week at the cabin.
This message was edited by flatcreeker on 10-14-21 @ 11:37 AM
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TomO |
10-11-2021 @ 7:43 AM
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Senior
Posts: 7243
Joined: Oct 2009
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My test set will test the generator and voltage regulator on the car. I don't know how your guy set the regulator, but it is unusual to have to adjust a new regulator. From your description of the problem, I think that your high voltage are caused by no regulation due to a shorted shunt resister in the field circuit of the regulator. The most common cause of this is a shorted or grounded armature or in the generator. It could also be caused by something on the firewall touching the resisters on the bottom of the voltage regulator. If you have the battery connected when you change voltage regulators, you might damage the regulator. I don't know what P/N Third Gen uses for their voltage regulator, just ask for one for a 1939 Mercury. The smaller pulley would not be contributing to your problem. It just allows the generator to provide voltage at a lower RPM. "Am I capable of testing the generator for faulty internal grounding with only a volt meter?" I don't have a procedure to do this with just a volt meter.
Tom
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