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Chris Johnson

USA
3751 Posts

Posted - 05/20/2011 :  12:23:43  Show Profile  Reply with Quote
Hello Art,

Thank you very much for taking the time to research this and post the write-up and pictures. I think this makes it possible for anybody reading all this to understand how it all works and what is going on in there.

It is my opinion that it doesn't really matter who is right, but it very much matters what is right. Ron and I can have a little fun giving each other a bad time but, ultimately, the facts need to be established otherwise this is nothing more than a social board, and I don't think any of us want to limit it to that. I think Ron is refering to the seal in the front of the PS pump (I'm sure he will clarify that), but I also think that it is important for other readers to understand that it really is in the front of the PS pump, not in the rear of the compressor.

At this point, what I am most interested in is how engine oil could be pumped into the PS pump. I have never seen this problem. The only scenario I can see that would cause this is if the return to the engine's sump were completely blocked. Since the compressor is force-fed oil by the engine's oil pump, the compressor and the front seal in the PS pump could experience engine oil pressures as high as 70 PSI (the rating of the oil pressure relief valve in the engine) if the oil could not return to the engine.

I can also envision another very unlikely scenario where the PS pump could suck engine oil past the seal, but this would require that the feed from the PS fluid tank be almost totally blocked.

In either case, the seal in the pump is not the problem, though it might appear as a symptom. You and I both have old seals that are approaching 50 years of age and don't have problems with engine oil in the PS system.

I'll be out until late this evening, but I look forward to reading Ron's thoughts on this.

Chris Johnson
If you aren't constantly impressed with your car, then it needs fixing.
100.012-12-000790
100.012-12-000867
www.300SE.org
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Ron B

Australia
11612 Posts

Posted - 05/20/2011 :  17:48:48  Show Profile  Visit Ron B's Homepage  Reply with Quote
Chris, As I pointed out, the seals on all vickers pumps are designed to hold pressure in .
So.. My own thoughts about the Compressor drain is that although the drain is large and it dumps directly into the bracket , it is the sheer volume of oil that is being pumped into the compressor housing which allows this to happen . When the lip seal dies, that oil is Sucked into the vickers pump via the low pressure side of the pump. And when it happens the oil is pouring out of the reservioir even at idle. Hot engine oil is easily sighted .. So,when the owner doesn't realize (or never bothers to look in the reservoir) it gets worse,a lot worse when the car is driven . That volume of oil becomes huge . In a matter of minutes most of the trans fluid in the steering is displaced and the engine oil takes over. I haven't seen any steering box seal failures but i doubt the flex hoses like it much.
The other thing to watch for when reassembling is to ensure that the two thick washers are against the pump ,between the bracket and the pump housing. If not,the pump housing will leak.
none of this stuff is in the manuals etc, but then they were written when the components were nice and new.. without several hundred thousands of miles on them.

On the matter of the oil volume,I dont know what sort of volume the engines pump can deliver but when I burst a feed line a couple of years ago ,the amount of oil sprayed all over the car in seconds was amazing. Even on a M116 ,which I had one burst at idle , the oil pumped out went everywhere before the engine could be shut down.

quote:
12-14-2004, 11:49 PM #8
Tom Hanson
MBCA Member

What the heck, try to stuff a MB 6.9 liter V8 in it. What a machine that would be..
__________________
Tom Hanson
Orange County Section

Edited by - Ron B on 05/20/2011 17:51:55
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Ron B

Australia
11612 Posts

Posted - 05/20/2011 :  17:56:53  Show Profile  Visit Ron B's Homepage  Reply with Quote
Art, thats the seal. it should be dual lip seal . Using a single lip seal ,of which i have found a few on the compressors which had failed, is not a good idea.
The outer O ring,generally doesn't do much because the fit between the housings is pretty good. a regular nitrile ring will work OK.
Do you want to sell those M189 bits?




quote:
12-14-2004, 11:49 PM #8
Tom Hanson
MBCA Member

What the heck, try to stuff a MB 6.9 liter V8 in it. What a machine that would be..
__________________
Tom Hanson
Orange County Section
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Art Love

Australia
6226 Posts

Posted - 05/20/2011 :  19:54:48  Show Profile  Reply with Quote
Not while I'm still running the W112 coupe and rebuilding the green car.

I'm not sure that I want to pull a power steering pump apart just at the moment to see if the other side of that radial seal is the inflow side of the power steering pump, not the pressure side, but, if it is, then what Ron says makes sense to me. There certainly is a lot of oil passing through the sump/coupling housing of the air compressor. The radial seal, while physically in the front of the power steering pump, is effectively the rear oil seal of the air compressor - an interesting Anglo-German collaborative design effort between Vickers and Knorr, even if they could not agree on the bolt specs. If the "suction" side of the power steering pump is behind that radial seal, it would effectively have a lower pressure than the "nil" pressure in the coupling without the necessity of a blocked oil return in the air compressor and suck oil if the seal failed. If the pressure side of the power steering pump is on the other side of that radial seal, then failure of the seal would result in power steering oil being pumped into the air compressor sump via the coupling housing. If there is neither suction or pressure on the power steering side of the radial seal, then its failure would be fairly benign unless the failure was gross.

Someone want to pull a power steering pump apart Paul Germy will have done so fairly recently, maybe he can tell me if no one else knows. I'll be doing it with Justin as well at some stage, but I don't think it is on his immediate agenda. It's all an education for me and I hope other readers will find it interesting as well including Tim and Kai.
Art
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Art Love

Australia
6226 Posts

Posted - 05/21/2011 :  22:40:10  Show Profile  Reply with Quote
I was talking to Justin yesterday about these air compressors. He has exactly the same thing on his trucks, just bigger. He showed me one disassembled from one of his trucks. He said the main problem with these air cooled pumps is that the bore and the piston become oval with time. He said that once they begin to pump oil, repairing them using the existing piston, even with new rings, results in only a short term fix before they start pumping oil again. He said that even though he measured the truck piston and bore and they were OK, his repair with new rings was short lived. His enquiries with his local expert revealed that the metal distorts as the pump gets hot and things become oval. Only solutions if that is the case are to buy a new pump or to bore the cylinder and put in an oversize piston. As these pumps are NLA new, once these is a lot of blow by, seems a rebore and replacement piston and rings will be the only answer.

So grab every one of these pumps from wrecks before they are crushed. I do not know if Knorr are able to supply oversize pistons or whether we will be forced to look elsewhere. I just post this for general advice. Overall, these little pumps are very durable with most still doing an adequate job after 40 years.
Art
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pjtigger

United Kingdom
153 Posts

Posted - 05/22/2011 :  13:10:42  Show Profile  Reply with Quote
Art

Your in luck - i remembered to take a picture of the PS pump when i overhauled it.





Hope this helps show how it works
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Art Love

Australia
6226 Posts

Posted - 05/23/2011 :  03:24:30  Show Profile  Reply with Quote
Thanks Paul.
I can see how it works in principle, but not in detail. Justin is not planning to pull one apart in the near future, so I'll have to remain ignorant for the time being. That set of O rings you listed does not seem to include the radial seal. I presume it is in addition to the O rings you list.
Art

Edited by - Art Love on 05/23/2011 03:29:31
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pjtigger

United Kingdom
153 Posts

Posted - 05/23/2011 :  07:11:39  Show Profile  Reply with Quote
Yes - the PS has a 22x35x7 seal
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Cardock

Ireland
91 Posts

Posted - 05/30/2011 :  12:20:11  Show Profile  Visit Cardock's Homepage  Reply with Quote
Can anyone confirm these measurements are correct. I measured the seal on my 600 p/s pump and it seemed more like 36/26/7. Are there a range of pump sizes, could the previous post relate to a smaller pump ? The part doesn't seem to be listed as a stand alone item on EPC so if anyone had a part no. that would be great (if it exists)

Gar
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pjtigger

United Kingdom
153 Posts

Posted - 05/30/2011 :  15:27:13  Show Profile  Reply with Quote
The size was for the 6.3 pump - could the 600 one be a different pump ?.
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Art Love

Australia
6226 Posts

Posted - 05/30/2011 :  23:22:33  Show Profile  Reply with Quote
The pumps are different. 100 460 03 80 for the 600 and 189 460 06 80 for the 6.3. Without going down into the garage and lifting bonnets, I don't know what the external differences are, but I would not be surprised if the 600 pump were bigger and worked at a higher pressure. I don't have a part number for the 600 radial seal.
Art
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Mercedes300sel

Iceland
4 Posts

Posted - 04/06/2015 :  14:38:52  Show Profile  Reply with Quote
Hi i have a 1970 300SEL 6.3 and I have taken the compressor out and apart and the crank is very worn because of the blocked lubrication lines, is there any thing I can do to repair it.
Regards Pétur
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cth350

USA
1523 Posts

Posted - 04/06/2015 :  20:54:49  Show Profile  Visit cth350's Homepage  Reply with Quote
Used pumps are around. Do be careful with pulley on yours as been probably said three times already on this thread, but it bears repeating as a used pump may or may not have a good one.

Also, anybody shipping a pump should ensure that it is packed immobilized and such that if dropped, the pulley won't suffer a catastrophic shock and crack. A few cm of styrofoam packing is a good thing.

-CTH
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Art Love

Australia
6226 Posts

Posted - 04/06/2015 :  23:27:06  Show Profile  Reply with Quote
If you know anyone in Iceland who is good with motor bikes or works on engines in general, show them the crank shaft for advice. There is nothing fancy regarding this small "engine" as far as the crank is concerned. It would depend on whether the wear is through the hardening and the availability of undersize bearings if the bearing surfaces are not beyond repair. If the crank is beyond repair, then you would need to buy a second hand pump or check with the Classic Center if they can still supply a new pump and at what price. They were still available new in the 1990's but I have not enquired since.
Art
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Mercedes300sel

Iceland
4 Posts

Posted - 04/07/2015 :  21:38:32  Show Profile  Reply with Quote
Thanks for the quick answer I appreciated, I will find some experts here in Iceland to take a look at it for me thanks again.
Pétur
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