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Generators & Electric Motors General Discussion Antique Generators and Old Electric Motors: Questions and answers about restoring and showing old power generation systems.

Generators & Electric Motors General Discussion

GM-6-71 running, no power


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  #1  
Old 09-03-2007, 04:58:16 PM
Walter J. Walter J. is offline
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Photo GM-6-71 running, no power

I finally got my new GM/Detroit Diesel 6-71, Model number I-4634, Serial No. 427-K-60(I think it is a 1960 model) running after changing all filters and the oil. I had to use starting fluid to finally get it going and I let it run about 15 minutes. It runs great! It will not start without the starting fluid. Any thoughts on why? Sounds great and not as loud as I thought. Now the bad news. The voltmeter jumps to about 5 volts and that is it. Does this mean the controller or voltage regulator is gone bad. I see Flight Systems can rebuild my Basler Voltage regulator KR7FF and maybe the control board (Delco RSMMTD?) as well. On one side is a cigar type device that has been disconnected. What does this do? Does it need to be connected? How can I tell what the problem is? Thanks.

Walter Jones
1960(?) GM Delco 100kw
Onan 30EK
1976 M35A2
1961 Lincoln Continental








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  #2  
Old 09-03-2007, 05:35:56 PM
Raymond Raymond is offline
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Default Re: GM-6-71 running, no power

It shouldn't need help,starting unless its cold. Does the fuel rack pick up with the starter or do you have to start on ether then it picks up the fuel? Try holding the fuel rack about 1/2 way open, then start it. If it fails to start or loads up on fuel you may have a serious compression problem or a bad set of injectors. If the fuel,pick-up is delayed you may have a governor or control problem. Make sure the primary fuel pump builds up pressure and the return is clear,(no air bubles) All of these problem will cause profuse smoking. (bluish white) with possible fuel sprayed out the exhaust. Also check that the blower is turning and the air damper is open. The starter should roll it more than 250 rpm for a first turn start. The generator is a little more involved and difficult to diagnose without some schematics and test results.
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Old 09-03-2007, 06:21:17 PM
Walter J. Walter J. is offline
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Default Re: GM-6-71 running, no power

There is not much smoke. It starts on ether then picks up the fuel. Maybe there is still air in the fuel. Wouldn't that resolve once it runs for a few minutes? What would cause no AC power? Bad controller/Regulator?
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Old 09-03-2007, 06:54:34 PM
KidDynamo KidDynamo is offline
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Default Re: GM-6-71 running, no power

Check your manual and see if a restricted oriface is needed in the fuel return pipework and if so, that it is there.

I would evaluate the fuel oil supply plumbing too. If fuel needs to be sucked from a low level tank, perhaps fuel is drainging back on shutdown, requiring a lot of cranking for the fuel transfer pump to refill the injector fuel lines.

A bit of a horizontal run on the suction plumbing and a swing check valve on the tank side of the horizontal run might be helpful to. I'd have to see it.

The idea is to have fuel flooding the fuel pipework when you first try to start and to not require a lot of cranking to have everything primed.

A quick check can be done if you temporarily install an outboard motor fuel priming sqeeze bulb into the fuel plumbing, before the fuel transfer pump, you can squeeze the heck out of the bulb prior to a cold start and be pretty sure of a "full" fuel system. (The engine should run fine with it in-line, though I don't know about full load.) Make sure the bulb and all the plumbing are air and fuel tight....no leaks.

If this helps to make for a quick cold start without ether, then you can implement some plumbing remedies. If not, go to the more involved tests.

Most good running 6-71's I've used start up real quick unless they are really frozen cold. Yes, the generator mass may take a second or two to get rolling but that's about all. I thought the original question came from Florida, so I assume it is relatively warm ambient temp. (?)
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Old 09-03-2007, 07:19:05 PM
Walter J. Walter J. is offline
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Default Re: GM-6-71 running, no power

I removed the old hoses as they were cracked and leaking to try a temporary start. Right now I have two 4 foot hoses in a jerry can. The large Deming pump sucks the fuel and seems to prime the system as it flows out and back into the can. Where would the restricter orifice be located? I do not have a manual yet as it is on order. 92 in the shade here, thus I do not think the diesel turned to gel.
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Old 09-03-2007, 09:54:27 PM
K D Redd K D Redd is offline
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Default Re: GM-6-71 running, no power

I went through this with a GW/Delco. Be sure you are running the engine at the alternator speed. You said the engine was not making much noise. This leads me to believe the engine IS NOT running fast enogh to excite the alternator.

Kent
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Old 09-03-2007, 09:55:51 PM
K D Redd K D Redd is offline
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Default Re: GM-6-71 running, no power

I went through this with a GM/Delco. Be sure you are running the engine at the alternator speed. You said the engine was not making much noise. This leads me to believe the engine IS NOT running fast enogh to excite the alternator.

Kent

Sorry, can not type
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Old 09-04-2007, 07:51:11 AM
Walter J. Walter J. is offline
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Default Re: GM-6-71 running, no power

Quiet is a relative term when working on Diesel engines. I was wearing earplugs. I do not have a tach but I would say it was running around 1800 based on whine of Engine. I think it is the board but have no way to test other than to pull it.
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Old 09-04-2007, 09:31:16 PM
Gunny Gunny is offline
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Default Re: GM-6-71 running, no power

Hard starting is probably a governor issue. Believe that thing is probably equipped with a Woodward. Phone companies had those things built to their specs and sometimes they asked for funny stuff. Sometimes they shut them down by dumping the governor oil supply with a solenoid. If so, you'll have to crank it until it builds oil pressure and then fills the governor. Might have had a solenoid to boost the rack to the start position.

It appears that yours is not original, someone seems to have replaced the control panel and who knows what they did with the control circuitry.

Basler regulator is not original to that machine either, I have seen them with Allis and Delco regulators. Measure output voltage and while doing that, what is the frequency? Mechnical governor should make it go at rated speed of either 1500 or 1800 rpm at 60Hz. If there is residual, might very well be the regulator, if no residual, might be as simple as flashing the exciter field. Measure the output voltage, also measure voltage to the exciter field (wires labeled F1 and F2 or X and XX), should be DC and post what you get here, we'll get you through it.

Try to no ether it to start it, not especially good for them unless done properly. Proper way to do it is to get the engine to crank and then give it a short snort.
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Old 09-04-2007, 10:16:47 PM
Walter J. Walter J. is offline
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Default Re: GM-6-71 running, no power

Gunny thanks I will keep you posted. What is the long cigar looking object in the bottom picture. It has been disconnected and is mounted on the side of the generator.
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Old 09-05-2007, 07:38:42 AM
armandh armandh is offline
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Default Re: GM-6-71 running, no power

those things are resistors [wire wound on a ceramic tube] with a high wattage rating. the ones with a sliding clamp are variable resistors.
given your electronic experience level you may need a bit of help once the engine is running well.
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Old 09-05-2007, 09:44:34 AM
Walter J. Walter J. is offline
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Default Re: GM-6-71 running, no power

Thanks. Do you need them? They have been disconnected. I have the local Detroit Diesel tech coming tomorrow to look things over and tell me what I need as I am over my head on the wiring side.
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Old 09-05-2007, 07:46:41 PM
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Default Re: GM-6-71 running, no power

Quote:
Originally Posted by Walter J. View Post
Gunny thanks I will keep you posted. What is the long cigar looking object in the bottom picture. It has been disconnected and is mounted on the side of the generator.
Walter:
That resistor was part of the original voltage regulator system. Not needed with a Basler.
Hope the Detroit man can help you. Wish you were closer, I'm pretty partial to those old 2 stroke Detroits and have excellent luck in making them go, boh ends, the engine and the generator.
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Old 09-07-2007, 11:01:06 AM
Walter J. Walter J. is offline
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Cool Re: GM-6-71 running, no power

Detroit Diesel Tech was out today and everything checks out on the generator and the old 6-71. I don't think it had been run in awhile and of course it started right up for him. The Basler board also checked out aok. I have a bad or sticking Murphy valve that opens but does not close to shut engine down. I also have a bad temp sending unit for the water temp. Two part changes and I should be ok. Other than that he thought I was good to go. Thanks for everyones help and comments.
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Old 09-07-2007, 11:08:34 AM
Walter J. Walter J. is offline
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Default Re: GM-6-71 running, Delco manual

The Detroit Tech let me copy the Delco Generator head Service manual DG-2 April 1970 which is 18 pages of maintainence intructions for the older GM Delco generator heads. If anyone wants a copy let me know as I scanned it in pdf.
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Old 09-07-2007, 03:28:12 PM
Jim Davis Jim Davis is offline
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Default Re: GM-6-71 running, no power

Congratulations Walter!
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  #17  
Old 09-07-2007, 03:42:34 PM
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Talking Re: GM-6-71 running, Delco manual

Quote:
Originally Posted by Walter J. View Post
If anyone wants a copy let me know as I scanned it in pdf.
I would like to get a copy of your Manual in .PDF Format.
<fastpath@btpost.net>

Bruce in alaska
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Old 09-07-2007, 06:19:28 PM
Walter J. Walter J. is offline
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Default Re: GM-6-71 running, no power

I am out of town and will get out the pdf on Sunday night for those who asked.
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Old 09-07-2007, 07:37:26 PM
Doogdoog Doogdoog is offline
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Default Re: GM-6-71 running, Delco manual

" If anyone wants a copy let me know as I scanned it in pdf.[/QUOTE]"

Aloha Walter,
Please send me a copy. TIA

< kasu@hawaii.rr.com >
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Old 09-07-2007, 11:56:21 PM
Jeff Conner Jeff Conner is offline
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Default Re: GM-6-71 running, no power

The GM 71 series generator engines I remember usually used the Woodward PSG or SGX governors. Both were hydraulically actuated by engine oil. For better start/stop control the oil supply was externally supplied from the engine oil gallery. For start/stop control, there usually was a normally closed solenoid valve on the oil inlet to the governor, and another normally open (dump valve)that bled off the governor oil pressure and dumped the oil back to the crankcase. Sometimes it worked with just one or the other valve, but the engines ALWAYS started and stopped quickly when the pair of valves were used together. Most generator engines also used a small oil reservoir located next to the governor, and it was piped into the oil supply line. This provided oil supply for the governor charge pump so it didn't have to wait for engine oil pressure before enabling the governor to open the fuel rack on starting.
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