Rudder tube grease fitting 316 stainless

One thing on my list for spring. My original rudder tube grease fitting is just a little rust stain clogging its hole. A replacement by a previous owner seems to be about halfway to that same state of decay. I found 316 stainless grease fittings at McMaster-Carr. Topping up that grease to prevent leaks is routine maintenance on the 32-3, and likely other Ericsons too. Pictures of part and it’s ordering info for convenience. It’s metric threaded, so likely need to drill and tap new hole.

I had a really difficult time matching a tap with a zerk fitting. Zerk fittings are almost all NPT threads and tapping an NPT hole to accept a fitting requires the tap to pass through the hole, but the rudder stock is in the way unless you drop the rudder. I did try a metric fitting like the one you have, but I couldn't find an affordable tap. I ended up epoxying in a reducer without tapping treads in the fiberglass. The reducer had large exterior threads and a1/4 18 NPT threads in the inside. I'm hoping this will give me the ability to replace the zerk fitting without having to break an epoxy bond. I detailed the install in post 51 here:

You can just epoxy the threads in, no real need to tap. Excerpt from blog entry:

The next morning I picked up a new half-inch stainless Zerk fitting with a quarter-inch inlet from a boat yard parts department. I drilled a half inch hole in the side of the rudder tube as deep as the Zerk threads. This didn't penetrate through tube to post. I drilled further with a quarter-inch bit, carefully probing. When I thought I was all the way through it was out of the slip again, full speed ahead again, down into the after berth again--and indeed water was squirting out of the new Zerk hole, proof of an open path to the inside of the tube.



I glued the new Zerk in with thickened epoxy and when it cured pumped in three 3-ounce tubes of marine grease through the new nipple. Pump, pump, pump, filling a void empty for who knows how long, and with a growing suspicion that the whole system relied heavily on grease, lots of it, probably an expected annual application of grease, an application that could not have been made through a rusted Zerk...

Christian Williams said:

You can just epoxy the threads in, no real need to tap. Excerpt from blog entry:

The next morning I picked up a new half-inch stainless Zerk fitting with a quarter-inch inlet from a boat yard parts department. I drilled a half inch hole in the side of the rudder tube as deep as the Zerk threads. This didn't penetrate through tube to post. I drilled further with a quarter-inch bit, carefully probing. When I thought I was all the way through it was out of the slip again, full speed ahead again, down into the after berth again--and indeed water was squirting out of the new Zerk hole, proof of an open path to the inside of the tube.

I glued the new Zerk in with thickened epoxy and when it cured pumped in three 3-ounce tubes of marine grease through the new nipple. Pump, pump, pump, filling a void empty for who knows how long, and with a growing suspicion that the whole system relied heavily on grease, lots of it, probably an expected annual application of grease, an application that could not have been made through a rusted Zerk...

Click to expand...

Christian,
You stated above that water was coming in through the newly drilled zerk hole, and then you epoxied in the new zerk and let it cure. I'm a
bit surprised that the epoxy was able to cure properly in that wet condition. Did you use a special epoxy that cures in water, or how did you manage that?
Thanks!
Frank
it

The hole is well above the static waterline. Underway, the stern squats and the wake come up which puts the zerk under water. You can use epoxy in this area without worrying about it getting wet as long as you are at a calm moorage.

Watch out for grease leaking out of the rudder tube! I found a big pile of grease under the rudder tube after pumping it full. Eventually I discovered a small hole where the packing gland seats. It’s filled with grease with no evidence of water leaks so I left it. I’ll probably need to reinstall the packing gland at some point.

I recenly got a package of 10 stainless fittings from Grainger. I also got a 1/4-28 thread tap along with the matching drill bit (#3?). The original fitting is a mass of rust, so I drilled a new hole at the same height, but in a convenient location (I can access it from the quarter berth). The fiberglass tube is about 1/4-3/8" thick, and it was obvious when I got through and hit the rudder post. Tapping was easy, as was installing the Zerk. Note that the fitting is tapered thread, but presented no difficulty going in the straight-threaded hole. I have pumped about 12 ounces of marine grease so far, with no sign of oozing anywhere, but it seems like more pressure is needed recently compared to the first pumps. The upper bearing has a stainless Zerk already, and only needed about 4 strokes before grease was coming out mostly at bottom, but also at top of the rudder post. The wheel turns noticeably easier now.