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445 Hydraulic Pump Leaking From The Relief Valve

J

JRMoline

Member
I have a 1958 445 that leaks profusely out of the power steering relief valve (on the pump not the damper valve up front). I have removed it, cleaning it and inspected the internal seat as well as I can. I've also examined the pump closely for cracks but nothing is evident. I'd like to remove the pump for further inspection and a possible rebuild but I'm not sure if there are any pitfalls when doing that. Is there anyone out there that can coach me on removing it. I have the shop manual but the instructions are very vague. I believe it's known as a Webster pump and the model is #10A8010.
Also I'm wondering if I'm looking at a weak valve spring but don't know how to test it. The manual says it should read 31.5-38.5 lbs. when compressed to 1 3/4". It looks good other than minor wear on one side but could still be weak. Any guidance will be appreciated. :?:
 
(quoted from post at 19:00:42 01/01/21) I have a 1958 445 that leaks profusely out of the power steering relief valve (on the pump not the damper valve up front). I have removed it, cleaning it and inspected the internal seat as well as I can. I've also examined the pump closely for cracks but nothing is evident. I'd like to remove the pump for further inspection and a possible rebuild but I'm not sure if there are any pitfalls when doing that. Is there anyone out there that can coach me on removing it. I have the shop manual but the instructions are very vague. I believe it's known as a Webster pump and the model is #10A8010.
Also I'm wondering if I'm looking at a weak valve spring but don't know how to test it. The manual says it should read 31.5-38.5 lbs. when compressed to 1 3/4". It looks good other than minor wear on one side but could still be weak. Any guidance will be appreciated. :?:
Click to expand...

Im sure you already know this but there is supposed to be an O ring on the plug if it is a regular hydraulic pump. Can you post a picture of the pump?
 
Here are pictures of the pump on the 445 and the model number tag. I've also included the pump blowup from the shop manual. It doesn't show an O ring between the plug (#7) and the pump body. Virtually all blowups in the manual show O rings where they are required. I feel I would change the cracking pressure if I added an O ring under the plug because it is set with shims inside the barrel of the plug. That's why I am suspicious of the valve spring compression pressure being weakened. Any thoughts?

cvphoto70120.jpg


cvphoto70121.jpg


cvphoto70122.jpg
 

The spring isn't your problem.

Unless low hydraulic bypass pressure is suspected/confirmed there's no reason to worry about it.

I checked the Agco parts lookup and there's NO o-ring or seal ring shown on the relief "plug".

That tells me thread sealant must have been originally used.

Did you use any?

I would clean the internal and external threads with BrakeKleen, allow to air dry, then install the plug with some good thread sealant.

(To get things reasonably oil-free with the pump in place you may have to drain the oil, as well as leave the plug out of the pump for a couple of days while oil in the pump drains out.)

That should fix the problem UNLESS the case is cracked.
 
THANKS! That seems like a reasonable conclusion and an easy fix. I had a fella service my hydraulics about 10 years ago and maybe he didn't use sealant or it simply deteriorated. The head on the relief plug is worn and it's obvious it has be out and probably torqued down in the past. The steering was working fine before the leak started so I think my pressure is okay. I'll need to get a gage and check it when I get the fluid refilled. I have it drained already so it shouldn't be too hard to dry things out. I have some Permatex and some marine liquid gasket material, either of which I think would be suitable. Thanks again for the tip. She's an old beast but has been a reliable starter in cold weather which is important since it's my main snow mover.
 
There is an O ring on mine. I have the replacement pump (10A17560 I believe) maybe that is why. I will check my Webster parts book on the O ring. If there is a recess in the pump or a space on the plug with no threads just above the plug end it is supposed to have an O ring. Some times MM didnt have everything listed correctly in the parts books. It also might have a copper washer, but yes, USUALLY MM listed them separately.
 
I looked in the parts books on the 5 Star, 4 Star, and early M5. All use the 10A9003 plug. M5 is the only one that shows an O ring, part number 10P2023. As I stated, a different pump number might have it and yours not. I do have a couple of old pumps I will check.
 
There is supposed to be an O ring on it. My Webster book lists it. My 1957 5 Star pump (same style) has the O ring as well. It is 7/16 I.D. according to the parts book. I believe it is 1/16" thick.
 
(quoted from post at 16:17:03 01/09/21) There is supposed to be an O ring on it. My Webster book lists it. My 1957 5 Star pump (same style) has the O ring as well. It is 7/16 I.D. according to the parts book. I believe it is 1/16" thick.
Click to expand...

Thanks for all of your research. I guess I'll pick one up and give it a try. Does that need to be the special high pressure type of O ring? I forget the term but I needed to use them when I rebuilt the steering damper valve.
 
I dont believe so. The pressure will be on the valve end past the spring it holds in. I believe it is about 1/16" thick. The book
listed it as 7/16" inside diameter. It wont go much beyond the threads on the plug and I believe it fits snug against the recessed
hole in the pump. If you cant find the proper one you might have to try an Agco dealer for 10P2023 O ring. (10A9003 is the plug
number)
 
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