Navtec "secrets" revealed
My backstay started leaking by the rod seal. I dismantled the unit as far as I could and like everyone else, could not figure out how to separate the square tube body from the pump base without risking damage to the tube. Fortunately after an extensive web search I found document that list a breakdown and parts listing for most of Navtec's products:
https://www.hisse-et-oh.com/system/...avtec_hydraulik_service_manual.pdf?1321964899
After removing the rod with the piston, there is a gland nut at the bottom of the tube that screws it into the base. The nut has a slot groove in it. I could not find a screw drive ANYWHERE that was wide enough. It must be 1 1/8 wide as there is a centre hole in the nut. (the top four screws in the cap only hold the cap on, also be careful removing the screw, ONE of the also covers a plug in the bottom of the screw hole that is part of the hydraulic circuit). Fortunately I have a machine shop and was able to manufacture the required driver out of a piece of 1 1/8 round bar that I milled one end into a flathead screwdriver point. I then covered the rod with tape so that it would not score the inner rod barrel. Total length is about 2 feet so that it can reach to the bottom of the tube. I just slid it in and the nut turned right out. I can gladly send pictures of it, or even SEND it to anyone that needs it (at no charge) by taking it to a UPS store, and you do the rest. Just send it to the next person that needs it and no charge.
I got the complete seal kit from
https://store.offshorespars.com/products/navtec-10-series-7-integral-backstay-adjuster-seal-kit
Al I can say is EXCELLENT. Just be ultra careful with the two little springs. Drop or mishandle them and they will bounce into orbit. I think one of mine is still orbiting the space station.
It gets really tricky with the valves. Just do them ONE at a time. And be careful making sure that you do not mix up the balls. Plus be ultra careful with the high pressure relief valve. Make sure the ball is seated perfectly before you reinstall the spring. It may hang up if not seated in the exact spot. Put the ball in and use a small hex key to make sure that it is seated before replacing the spring. I eventually put the ball on the end of the spring holding it with the ball sitting on top of the spring and sliding it up in the valve body with valve body above it. This little step took me a month to figure out. When the pump was reassembled it would not build pressure, I could see oil moving back and forth out of the reservoir, a clear indication that a valve was not seating. This unit is extraordinarily designed with some of the hydraulic passages serving two purposes. I found this after hours of putting probes through the passages in order to figure out the hydraulic schematic. Like the nut at the bottom of the tube barrel, once you see it, it is clear, but a mystery until you do see it. I my case there was a score mark on the valve seat that I could only see with help of high magnification from my smartphone (a really helpful tool). Once I lightly used a drill (using my fingers, not a drill) to remove the burr, it built pressure on the first pump.
For the piston seal, I see this is also a source of trouble for people. I found two large sockets, putting one at a time on against the seal and putting the whole thing in a smooth jaw vise (I just put several layers of shop rage over the jaws) I just carefully closed the vise pushing the seal up into the groove in the piston. One socket will only push the seal part way until it runs into the taper of the piston, then just switch over to the next larger socket to push it the rest of the way. Also do not put in the Teflon bushing into the same grove until the piston seal is in the grove. And even then only after you put the piston onto the rod and reinsert the pin that holds the piston to the rod.
Just play out each couple of steps ahead of time in your head so you do not have to redo anything.
The unit is brilliantly designed and not all of its features are initially apparent, and it is huge EXPENSIVE, but well worth the effort. As a side note, mine has been installed for about four months and not a single drop of oil or drop in pressure.
P.S. DO NOT USE red transmission fluid. It will appear to work BUT WILL eventually destroy all the rubber seals. Use 30 W non detergent (I used hydraulic jack oil).
I know this is a long winded reply, but I just wanted to help anyone that is in the same position.
If you have questions or want to borrow the tube nut tool, or just want pictures of it, just ask.
jsocket@interlog.com