Ca slow hydraulic leak?
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Category: Allis Chalmers
Forum Name: Farm Equipment
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URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=170216
Printed Date: 22 Oct 2025 at 4:09pm
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Topic: Ca slow hydraulic leak?
Posted By: Hunt4Allis
Subject: Ca slow hydraulic leak?
Date Posted: 17 Apr 2020 at 11:39am
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So I thought that I was golden but I've discovered that the elbow that is threaded into the top of the pump that feeds the right cylinder is slowly leaking... (The elbow is probably not the correct fitting as it looks to be maybe a gas line type fitting...) I used a paste type thread sealant when I installed this elbow into the pump threads, but I'm wondering if I should have used a Teflon tape thread sealant? Thanks Matt 👍 |
Replies:
Posted By: Jim.ME
Date Posted: 17 Apr 2020 at 2:08pm
| An oil rated paste should be fine. Some places, and people, will not allow Teflon tape on hydraulics or pneumatics as tape can get into the system if not applied carefully. It may need one more turn, don't break it. |
Posted By: Hunt4Allis
Date Posted: 17 Apr 2020 at 2:53pm
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It was as tight as possibly I could get it before I thought if I tightened it one more turn it's going to break something... It's definitely leaking around those threads I'm not sure that the stuff I used is oil rated paste. |
Posted By: Hunt4Allis
Date Posted: 17 Apr 2020 at 2:56pm
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It is actually made for up to 12,000 PSI hydraulic leak proof... at any rate I'm going to have to take it back apart and see why it's leaking I did notice when I had it all apart on my workbench that the threads were less than great. but when I tighten the elbow into it it seemed to snug up nicely. |
Posted By: Dave(inMA)
Date Posted: 17 Apr 2020 at 3:19pm
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Matt, bummer that the elbow is leaking! If the threads are damaged, replacing it sounds like the right answer. I used a similar plumber's paste when I reassembled my pump. No leaks so far. ------------- WC, CA, D14, WD45 |
Posted By: Jim.ME
Date Posted: 17 Apr 2020 at 4:30pm
| If it is pipe thread it may be worth the price of a new fitting to replace the old one. Be sure to get a true hydraulic fitting, not a hardware store grade fitting. |
Posted By: Hunt4Allis
Date Posted: 17 Apr 2020 at 6:40pm
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Ok, maybe I did not use enough paste on the threads(I was super careful not to get any near the end of the threads and I barely used any at all so maybe that's why it's leaking?) I really doubt this fitting is an actual hydraulic fitting (it looks like a standard cast metal elbow) |
Posted By: MACK
Date Posted: 17 Apr 2020 at 8:55pm
| Use red Loctite and a steel fitting, no cast iron or today's plumping fittings, they are junk. |
Posted By: Bill Long
Date Posted: 17 Apr 2020 at 9:02pm
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Back in the 50's we used number one peremetex (?). Worked fine. I do agree with getting the right elbow for hydraulics. Check the threads to be certain they are not damaged. Good Luck! Bill Long
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Posted By: Hunt4Allis
Date Posted: 17 Apr 2020 at 9:09pm
| Ok, anyone know what thread it is inside the pump valve where the elbow turns into and what thread the other end is on elbow that the hydraulic line attaches to? |
Posted By: Jim.ME
Date Posted: 17 Apr 2020 at 9:30pm
| The part book calls it a street elbow. I have a photo of mine, in place, and I would say it is pipe thread. As for size of each thread, I can't tell you at this time. If you take yours to a parts store, that makes hoses, or a hydraulic shop; they should be able to match it, a street ell is a common adapter. |
Posted By: Hunt4Allis
Date Posted: 18 Apr 2020 at 6:48am
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Mack, Does red loctite fill in worn out threads? I can't believe this thing has a leak because it tightened into the pump body very very tight... |
Posted By: Jim.ME
Date Posted: 18 Apr 2020 at 7:29am
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Loctite 545 is their actual fitting thread sealant/locker and it is red. It is a good product. It may fill the threads and hold, it is used in a lot of mills and industrial plants. Threads deform when tapered pipe threads are screwed together and may not match up well when re-used. Sometimes using a combination of thread tape and sealant (sealant, tape [3 wraps], sealant) helps. If you do this keep the tape back at least 1 full thread from the end of the male thread on the fitting to avoid it getting inside the female side. Could there possibly be a crack in the fitting threads? |
Posted By: CTuckerNWIL
Date Posted: 18 Apr 2020 at 8:22am
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Pitch the elbow in the scrap pile and get the right fitting for it. Common water and gas pipe fittings aren't made for hydraulics and sometimes crack in the root of the thread, making it almost impossible to see. It's most likely a 3/8 NPT thread, but I don't know what you have for a connecting thread. https://www.google.com/search?q=3/8+npt+hydraulic+elbow&client=firefox-b-1-d&source=univ&tbm=shop&tbo=u&sa=X&ved=2ahUKEwiWv6aNiPLoAhXMQs0KHTjRDfQQsxh6BAgMECs&biw=1280&bih=608&dpr=1.25" rel="nofollow - https://www.google.com/search?q=3/8+npt+hydraulic+elbow&client=firefox-b-1-d&source=univ&tbm=shop&tbo=u&sa=X&ved=2ahUKEwiWv6aNiPLoAhXMQs0KHTjRDfQQsxh6BAgMECs&biw=1280&bih=608&dpr=1.25 ------------- http://www.ae-ta.com" rel="nofollow - http://www.ae-ta.com Lena 1935 WC12xxx, Willie 1951 CA6xx Dad bought new, 1954WD45 PS, 1960 D17 NF |
Posted By: Dave(inMA)
Date Posted: 18 Apr 2020 at 9:47am
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I located the elbow in the CA parts manual online: p/n 70227215 "Street Elbow". My old print version lists 901722 which I guess translates to 70901722 with the updated p/n's. Not sure why there are two different p/n's, and I'm not disagreeing with the recommendations to switch to a high pressure hydraulic fitting - just noting what AC used at the time. I know that the elbow in my CA doesn't look at all like the ones suggested by CTucker - it's a steel street elbow from what I can see....which doesn't make it the safest approach, just what it is. Dave ------------- WC, CA, D14, WD45 |
Posted By: Jim.ME
Date Posted: 18 Apr 2020 at 11:17am
| "Street elbow" is the title of a style of elbow (male on one side and female on the other) and can be made of many different materials and have different ratings. The original AC elbows may look similar to what you see in hardware store but they are slightly different and heavier. I expect the AC ones were made out of better material than the ones in hardware stores today. A true steel fitting is better than the mallable iron ones at the hardware store. You can still get steel street elbows in sch 80, 160, etc. often used in steam service, and such, that look more like the old AC ones. The right answer these days is to use an elbow made for hydraulic service. JMHO |
Posted By: Dave(inMA)
Date Posted: 18 Apr 2020 at 12:19pm
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Jim - thank you for the education. I wonder if the cubed shape of the hydraulic version would cause an issue - that elbow fits into a fairly tight spot. Suspect the only way to know for sure is to try one! ------------- WC, CA, D14, WD45 |
Posted By: Jim.ME
Date Posted: 18 Apr 2020 at 1:08pm
| Trying one will be the only sure tell for sure. From looking at my CA I think one will fit. Here again there can be some size differences between manufacturers. |
Posted By: Hunt4Allis
Date Posted: 18 Apr 2020 at 6:21pm
| Thanks for the link to the correct type of fitting. It would be nice to have the female part be able to turn so that I don't have to rotate the hydraulic hose around in circles to get it to go together again...(it's in such a tight spot ya know) |
Posted By: Hunt4Allis
Date Posted: 18 Apr 2020 at 6:26pm
This is the fitting( silver- greyish)
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Posted By: Jim.ME
Date Posted: 18 Apr 2020 at 6:55pm
For pipe thread you can get a straight swivel adapter which would screw into the elbow. Or you can get an elbow with a swivel adapter. You need to be sure the hose end has the seat to match the adapter. Most new hose pipe thread fittings will have the seat, its about 50/50 on old hose fittings. I prefer these over hose fittings with swivels made in them, which are also available. 
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Posted By: Hunt4Allis
Date Posted: 23 Apr 2020 at 5:44pm
| So thanks to ( Brenda)Sandy lake I got a new hydraulic fitting from her and installed today and no leaks!(I'm ready for some brush hogging and fence post drilling!) |