Vacuum pump seized?

I got this DV-142 vacuum pump (refrigeration style) and am a little bit disappointed. It seems seized. If I turn it on, it shakes, the
motor hums, but the pump does not spin. The motor is coupled to the pump with a flexible coupling and it becomes visibly strained, but no movement. The motor seems to be fine.
I have a feeling that this pump is rusted inside and should be simply thrown away. While I am upset about it, the rest of the stuff in that lot seems like good stuff, such as a box of belts, 100 lbs Owatonna universal puller kit, concrete vibrator and two manual hydraulic pumps, so on balance it is likely to wotk out. But the pump is in quite sad condition.
i
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freon plus moisture produces acid which corrodes the insides of refrig pumps - i'm not surprised it's seized. oil may free it (try kroil) or try coke - the acid and foam will often free stuck pistons in a few days
On 11 Feb 2006 06:44:48 GMT, Ignoramus11720

Bill
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On Fri, 10 Feb 2006 23:37:43 -0800, William B Noble (don't reply to this

Thanks Bill. I already filled the pump with oil, I am kind of doubtful that it will help. I may remove the motor and try to turn the shaft with a wrench. As for Coke, do you suggest pouring it in instead of vacuum oil?
i

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since the pump is now working you don't want to try the coke trick, but.... it's an old engine trick - you can often free stuck pistons from their cylinders even when there is pretty heavy corrosion by pouring coke into the cylinders and letting it sit for a while - this would not be the first thing you would choose, but it's better than cutting the pistons out with a cold chisel (which I had to do on my 38 plymouth).
On 11 Feb 2006 19:58:33 GMT, Ignoramus1088

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On Tue, 14 Feb 2006 22:59:02 -0800, William B Noble (don't reply to this

Bill, I will remember this trick. Meanwhile, I have located where the exhaust comes out of -- it comes out of the carrying handle! There is a little threaded bit on it, so, I think, I will be able to attach an exhaust filter. I have intake and exhaust filters from truly broken (fully rusted) 1/3 HP vacuum pumps.
I think that installing exhaust filter will help with "oil mist" issue.
Thanks Bill.
i

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    The optimum filter should provide metal onto which the oil condenses, and be shaped so the condensed oil runs back into the exhaust port to return to the pump for re-use.
    This is easier with a pump with a vertical exhaust, of course.
    Enjoy,         DoN.
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It is horizontal in my case... Anyway, the filters are also horizontal.
i
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Sorry to hear that. It always sucks when you get a bad deal. But I certainly wouldn't chuck the pump without dismantling it. When I got my Edwards pump it was seized, though turning the pulley by hand freed it. On dismantling I found only a minimal trace of dirt and corrosion - not enough to affect the performance of the pump once it had been cleaned out, but enough to seize it because of the very tight clearances. These pumps are never easy to turn over, even when it perfect condition, but naturally the motor should be able to turn it! I would dismantle it and see what you find. A clean might solve the problem and be all that is required for a de-soldering system, but you're likely to need to replace the seals, gaskets and oil if you want good performance. Also, you'll get to see the mechanism, which is really cool. It was so cool I took some photos of the mechanism and turned it into a GIF animation, which I meant to put on a web page about my vacuum pump project. I never got round to it, but one day I will...
Good luck!
Chris
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wrote:

Thanks. I must say that that lot had two surprises. The vacuum pump is likely bad. That was a bad surprise. But the rest is surprisingly good stuff. I bought a huge (120 lbs) universal puller kit from Owatonna (for heavy equipment), in beautiful condition, and a WYCO concrete vibrator that sells for over $200 used on ebay. Plus a big box of automotive belts, including cummins.
Not bad for $57, even if the pump goes to garbage (sans the motor).

Thanks Christopher. I will definitely not throw it away without dismantling the pump.
i

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If the pump was totally emptied of oil when you got it, it might be fine. Try turning it by hand to get the oil into the tight spaces. As I said, there's a hell of a lot of friction in these pumps even when they're running normally. I wouldn't be surprised if it was impossible for the motor to turn a pump which had been drained of oil.
Chris
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are you trying to pump something that has pressure in it? that will stop a vacuum pump. Vacuum pump oil has no wax in it, and is resistant to moisture absorbtion, regular refer oil is not the same i would flush the pump(well can't use r-11 anymore) then refill with vacuum pump oil turn over by hand. my big pump 8cfm would not pump at all, then flushed it and put fresh oil, still works like a champ 25yrs later. Won an arguement with the eng. staff at singer corp(hvac div ST.L.) small pump is 30 yrs old still pumps down like new! tt
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Thanks! My pump is 5 cfm. I got it to work last night, after disassembly and turning it with a wrench. Washed the housing, put in new vacuum oil, ran it for a few hours, it runs pretty well. Will try adding valves and a gauge.
i
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Couple of additional points come to mind...of the "ingrained below the usual need to mention them" sort.
Got a filter on the exhaust? Got the exhaust routed outside? Fine oil mist is a considerable health hazard, and over the time that I was working with pumps, keeping it out of people became an increasingly elaborate exercise, with both filtration and ducting to carry it away. There's not much, but it does not take much to cause damage, either. You do not want this stuff in your house, your kids, etc...
If you are running the pump to warm and dry it, best to pump on a closed vessel, or plug the intake, rather than pumping air through it - vacuum pumps like to work at a vacuum.
When you stop the pump, best to vent the pump up to atmosphere. If you want to keep a (low-quality) vacuum on something connected to it without running it all the time (which is the usual method), provide valves so that you can shut off the pump from the vessel, and vent the pump intake without venting the vessel.
"Vessel" is whatever - bell jar, vacuum laminating bag, etc...
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wrote:

No... You are making a very good point actually, I wanted to ask a question about that. First of all, I have not actually found the exhaust port. I suspect that it may not be easily converted to exhaust filter.

I completely agree here.

I did just that yesterday -- ran it for several hours with the closed intake port. That completely cleared the oil of bubbles. I appreciate your suggestion.

Yes, that's also 100% right. I think that the way I will use the pump is, I will run it continuously while I need the vacuum, and let air in once I do not need it.
i
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