Update 2
Success!
After coming home from work last couple of days, it was raining off and on so out I went and continued to work it. I was able to get the thread chaser to screw in and tried to use it to clean up those ‘bad threads’ at the bottom of the hole I highlighted before. I was getting more resistance than I would have expected so again I took the cautious approach and stopped. Looking in the trim cylinder hole it’s obvious the threads go all the way to the bottom. Is it possible the manifold threads do not? I took a closer look at the endoscope pictures and started to suspect what I thought were bad threads at the bottom of the hole were instead simply no threads by design. Huh? I started searching the web for pictures of this manifold block (Part No. 3852559) and sure enough found very clear evidence that is not threaded to the bottom! See picture and mockup. In the picture the squiggly red and blue lines are shown as the red and blue ‘seats’ in the mockup. Also, in looking at the hose with the O-Ring installed the O-Ring does not seat against the flare of the tubing; it is sized to perfectly fit on the smallest diameter of the tubing, see picture. While it’s possible to force the O-Ring onto the slightly larger diameter where it would rest against the flare it’s my experience that is not how O-Rings work > their diameter is not meant to be stretched. The VP Workshop manual for Sterndrive and Transom Shield make no mention of trim hose installation other than to say, “Coat new O-Rings with hydraulic fluid and place them on the lines. Tighten to 84-108 in lb.” Regardless I followed my gut and did not push up the O-Ring to the larger diameter. I figured that if it needs to stretch out and go there, it will do so when the nut is tightened down.
So, I remain a little confused at exactly how these fittings work. And the pressure is significant > more than 1000 PSI at times.
But I digress. Here is the rest of the story.
Post ‘threads do not go to bottom’ understanding I started measuring the best I could to ensure the actual treads were fully cleaned up (the chaser was same length of the nut, so used that as a gauge). Using plenty of WD-40 with the multiple thread chasings followed by air blasts the smoking gun finally presented itself: a thin curled hair of metal. Anyone who has stripped threads knows this tell-tale. Here is my hypothesis: when the hoses were replaced there was a slight stripping of the thread, just the crown of the thread, not the root. And this sliver of metal interfered with the hose nut precluding it from fully seating but just a teasy bit. No leaks until after some time the ‘not fully inserted’ nut allowed a whisper of a leak to occur. (I did try to tighten it as the first step but it still leaked and post getting it out the O-Ring was in good shape.)
Convinced I now had reasonable treads – or maybe I was just cold – I inserted the hose using a couple of screwdrivers as fingers. One to push the nut up to the manifold and the other, with a rubber tip (see picture), to turn the nut. The trick was to have the nut nice and square on the manifold and held there. I used some spring clamps for this (like a close pin). But initially I did it the easy way: the hose was on the incorrect side of the gimble bearing grease tube. This was done as practice to see if the nut would turn into its threads using the screwdriver. Said differently, I needed to see if the nut would catch nice and easy and it did. Good. And it was an easier set up on the wrong side of the grease tube. Resetting it on the correct side, it was much more difficult to get it square but finally did. A few ‘pushes’ with the screwdriver and it took hold. I initially snugged it down to seat it but then backed it off so the tube could swing. Put the hose behind the hose clamp and loosely tightened its bolt. And then got the other end into the trim cylinder. After making sure all looked good with no twists in the hose, torqued down the hose and clamp nuts.
Removed the drive support devices, held my breath, and cycled it up and down to get rid of the air, filing the reservoir as needed. After a 6 or so cycles, did my inspection and no leaks!
I know this is a long write up so I will post a summary of the key elements to get this done. And if I can get some information on these fittings, I’ll share that as well.
For now, I need to finish getting the boat ready for the season and I am ecstatic I am going to have one!
