Tue 25 May, HHN day 42: New seal kit installed into the outhaul cylinder. My version of hydraulic oil filling and air purging process. Ready to fit back into boom tomorrow.
Last of the cool days today. Must make the most of it outside while I can. Having finished the rudder, my next priority is to finalise the boom. Ideal outside work.
The boom has been waiting on the outhaul system to be reinstalled inside. The system being hydraulic piston with sheave carriage, outer end sheave, lead-lines, and finally the 2 boom ends put back on. The main hold up has been the seal kit for the cylinder.
I had ordered the kit for the 2008-2012 version of the cylinder (boat was launched 2008) whereas it transpired that my cylinder is the 2004-2008 version with slightly different seals. As usual, Ludvig in Hallberg-Rassy Parts did the battle of patience with Selden and finally received the correct kit last Thursday, then managed to get UPS to pick up the same day, arriving here yesterday. I’m starting to think of HR-Parts as HR-Amazon!
I have already changed the outer seals on the piston itself, but there is still one internal seal to the piston. I tried to remove the piston from the rod previously, but with no luck. This morning I have Ray’s help. But try as we might, the piston still refuses to unscrew from the rod. So I give up on that one.
As this seal is not a moving seal and has been in the oil all the time, I’m convinced it mostly likely would not need changing anyway. And trying to get at it looks like we would have to get seriously rough with it. Which may end up with more damage than good.
While waiting on the right seal kit to arrive, I have been researching how to do the minutely difficult task of installing the rod seal, which is situated inside the cylinder end fitting. The piston rod goes back and forth through this end fitting each time we use the outhaul. So it has seen a lot of movement and definitely needs renewing.
YouTube videos on the subject all show technicians installing rod seals into large cylinders. Well, frankly, anyone can do that! But there is nothing on how to get a stiff rod seal into a 25mm diameter hole that I cannot even put my finger into!
However, this morning I am armed with a little knowledge, a seal twister tool, hot water, petroleum jelly, and punches which I have rounded the ends of. The water slightly softens the seal making it more flexible. The seal twister contorts the seal to allow its diameter to be reduced so you can get it in (in theory!), petroleum jelly for lube, and smooth ended punches to do the prodding to persuade the seal into its internal slot, without damaging it.
The hot water works a bit. The jelly just makes everything too slippery, and the seal twister still does not reduce the size enough to get it in. It is one damned fiddly job!
On my 3rd attempt, I finally manage to locate one edge into the slot then gently prod the rest of the seal into place. I feel like a bloody gynecologist working on a mouse! When it finally submits and the last seal edge slips in, you could have heard my whoop for joy a mile away!
With the seal fitted back on the piston rod and screwed back into the end of the outhaul cylinder, the next task is to try to refill the piston with hydraulic oil and purge (expel) all the air. Selden documents the method on how to do this when it is already installed in the boom and the boom is back on the boat and linked up to the boat’s hydraulic system.
But, for me, I would rather do it now. Or at least get 95% of the oil in and air out before it goes anywhere near the boat. Hydraulic oil escaping inside the boom and draining onto the boat is an unthinkable but quite likely scenario!
Then Paul turns up for a chat, just in time for me to put him to work! Together, we manage to cycle the piston back and forth, sucking in oil while at the same time raising and lowering the ends to allow air pockets to bleed out. It is quite interesting to see how quick one oil container empties while the other one fills as we cycle the piston.
This all sounds simple, but the piston cannot be moved by 2 manpower alone.
To pull the piston out, we use Paul’s car to anchor one end of the outhaul cylinder while I pull on the piston with a block and tackle secured to one of the mast stands. And to close the piston, we again need a block and tackle forcing the rod back in.
It all looks like a recipe for disaster and you certainly won’t find such a set up in any operating manual (!), but it all worked swimmingly well.
All in all a very successful operation, apart from one glitch. We run out of hydraulic oil! And there is no way a local supplier will have such a rare oil type. But, inside the boat, our hydraulic system has a big reservoir, full of the stuff. I’m very reluctant to get hydraulic oil from there, as I fear a spillage into the bilge while trying to extract it. But using a simple hand pump which we use to drain the dinghy, we do manage to get 1 gallon out without spilling a single drop. Incredible! I’m starting to think Paul is some sort of lucky charm today! Thank you, Paul!
Later in the afternoon, I clean up the outhaul cylinder and paint the few areas where my previous beautification has gotten chipped.
Then I install the sheave carriage onto the end of the piston, and the new sheave wheel in the outer end of the boom. The old one had literally disintegrated! It was clearly not up to the job, and the powerful hydraulics had killed it. This time I install a heavy duty Lewmar block, rated to 5 tones.
And there we are. The whole day on hydraulics. But it has been very interesting and I am happy we are ready to install the piston back into the boom tomorrow.
Now time for a curry, beer and bed!
