Very cool write-up and project. Thanks for sharing. From: Dennis C. via CnC-List <cnc-list@cnc-list.com> Sent: Sunday, January 7, 2024 3:44 PM To: CnClist <CnC-List@cnc-list.com> Cc: Dennis C. <capt...@gmail.com> Subject: Stus-List Navtec hydraulic backstay - amateur rebuild
A fellow boater had a Navtec integral hydraulic backstay adjuster that blew the top seal. As many of you know, this is probably the most common failure for these. Exposure to UV and the elements deteriorates the rod wiper at the top of the cylinder and it's downhill from there. (I recommend a 1/2 washer on top of the cylinder.) This list has been down this road many times. There's always a discussion whether to take the thing to a local hydraulic shop or let Lew Townsend in Seattle rebuild it. For the record, I sent Touche's adjuster to Lew a couple years ago and am a satisfied Lew client. So I called Lew and chatted with him about this "orphan" adjuster. He asked some critical questions. Was I going to keep it as a spare? Was I going to try to auction it? He commented that neither option was particularly economical. Hmmmm. Then we talked about snow skiing. We're both avid skiers. After some thought, I tended to agree with Lew. Including shipping, a rebuild would be north of $400-500. An expensive gamble to have it sit on eBay for weeks like others I've seen. So I decided to give the rebuild a shot myself. The Navtec seal kit, IF you can find one, is about $200. Philosophically, it's not much more than a manual hydraulic jack that compresses rather than lifts. Internet research turned up a set of rebuild instructions. See here: https://www.plaisance-pratique.com/IMG/pdf/navtec_hydraulik_service_manual.pdf Armed with instructions and a pair of calipers, off I went. Disassembly of the cylinder was fairly straightforward. I found several equivalent seals at mcmaster.com<http://mcmaster.com>. For those who are really interested, parts below are referenced on Page 8. Part Qty Navtec Mcmaster Price 31 2 HJ-2-215 9452K36 $12.08 (Needed 2. Had to buy 100) 35 1 HI-005 9505K39 $4.83 36 1 HN-002 9403K55 $2.30 Jug of Fram Hydraulic Jack Oil AW32. $10 Reassembly went well. I strapped it between two trees in my backyard and pressured it up. I noticed the thing was leaking from the pump piston. Okay, I pulled the pump handle and piston. The piston rod seal disintegrated when I removed it. Turned out this is a generic U seal with o-ring 1/4x1/2x1/4. Internet search on the Navtec number turned up numerous suppliers. I bought it from Crescent Hydraulics in south Florida. Part Qty Navtec Crescent Price 39 1 12500250-250B P125-00,250-250B $4.05 It's now back between the trees pressured up to 500-700. Hard to tell because the gauge lens is very crazed. But it seems to be holding. I'll know for sure in a couple days. Granted, I did not get into the actual pump assembly and all the check valves, etc. The cylinder walls, rods, etc. seemed to be in excellent condition so no polishing was necessary. So far I'm in it for less than $50. I want to replace the pressure gauge. I can't find a generic one that is equivalent. It needs to be a certain shape for the gauge cover to fit it. It looks like a gauge off a fire extinguisher. Oh. well. A challenge for later. -- Dennis C. Touche' 35-1 #83 Mandeville, LA
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