John E3
Active Member
Our sort of new to us 370AC had 7 quart jugs and an almost empty gallon of Dextron II oil, plus stop leak hiding in the back of the engine room, which I found over the winter. Not a good sign. Neither the seller, nor the surveyor, mentioned or noticed it, or any need to add some. The seller later said he knew nothing about it. He only owned it about a year, and he runs the marina, so I think he's being honest.
After removing the holding tank from below the genset, and cleaning all the genset oil out of the bilge (another saga I've posted about - hole in block and missing rod) I found that more oil had accumulated over the next week or so. This time it was red. I found traces of oil coming from the port coupling, and after reading some posts here and online it seemed like the obvious issue was a leaking seal. Thankfully there is enough clearance to replace the seal, in place.
I split the coupling and a couple ounces of oil poured out of the center. Some more quality time here and online led me to the coupling nut being the culprit. It has a machined washer on the back, and nylon insert on the front, and between the 2, seals the spline from leaking oil. The outer coupling seal is dry. Given the spec is about 220ft/lbs I gathered up the tools I expected to need, and finally crawled back there expecting to need a 2ft extension on the breaker bar only to find that it took near zero effort to turn the nut. This was good and bad news. Good that it was easy to get off, but bad in that it was not tight. Installing a new nut was uneventful.
This leaves me rather concerned however. Why was the nut loose, and what are the implications of it being loose? The sea trial with the surveyor did not indicate any unusual noises, although WOT was a bit low (props had some heavy dings in them) and the bottom is in need of a heavy sanding, many divots from layers of chipped paint.
There is whole section in the service manual about pre-load and shim washers on the outlet shaft. If the nut was loose, could it cause damage inside, or is it possible the shim washers may have worn resulting in the nut becoming 'loose'? The machined washer on the nut was also separated from the retaining flange on the nut. I should have used a mirror to inspect the spline, or pulled off the coupling to inspect, but didn't think of either until now. It's not too late yet, but the nut is not reusable.
The procedure calls for preassembling this shaft assembly and torqueing the nut to 50 ft/lbs and taking some precision measurement on the coupling end play. The goal is to adjust the shims to create an allowable endplay while maintaining a certain amount of shaft break loose torque. Then you take it apart, set it aside and continue assembling the rest of the parts, and then torqueing the nut to 220ft/lbs. (the range is pretty wide, 160-250 IIRC).
My torque wrench only goes to 150, so I opted to make it as tight as I could with 24" of breaker bar. The break loose torque is now much higher than it was, easily turning with a 8" socket wench, but too tight to turn by hand (it's slippery from oil and hard to grip). When I was inspecting the shafts a while back, I was able to turn both by hand, but barely. Again, I didn't think to check this again before I left yesterday, and see how they compare now. Since I was not able to turn it from inside, I was only able to get 2 bolts in, so it's not quite a fair comparison till it's torqued tight on all 4.
There is no visible oil on the dipstick, so that's concerning as well. I'm going to drain whatever might be left and study it closely for any metal. I don't think I got more than 1 cup out of the bilge since fall, and some was from the genset, for sure. It holds 2qts. The color of the first round of soaking with absorbent pads seemed a bit off for standard motor oil, but I didn't give it much thought till I had the bilge pumps out and all of it cleaned up, then a distinct red reappeared. The surveyor (and I) disregarded the genset oil situation as the seller stated there was something wrong with it. Way more than he alluded to, but he's not a mechanic.
Short of a tear down, or replacement, any suggestions of what else to look at, or check? I believe there are specs in the manual for pressure testing, but that is an in water test.
John
After removing the holding tank from below the genset, and cleaning all the genset oil out of the bilge (another saga I've posted about - hole in block and missing rod) I found that more oil had accumulated over the next week or so. This time it was red. I found traces of oil coming from the port coupling, and after reading some posts here and online it seemed like the obvious issue was a leaking seal. Thankfully there is enough clearance to replace the seal, in place.
I split the coupling and a couple ounces of oil poured out of the center. Some more quality time here and online led me to the coupling nut being the culprit. It has a machined washer on the back, and nylon insert on the front, and between the 2, seals the spline from leaking oil. The outer coupling seal is dry. Given the spec is about 220ft/lbs I gathered up the tools I expected to need, and finally crawled back there expecting to need a 2ft extension on the breaker bar only to find that it took near zero effort to turn the nut. This was good and bad news. Good that it was easy to get off, but bad in that it was not tight. Installing a new nut was uneventful.
This leaves me rather concerned however. Why was the nut loose, and what are the implications of it being loose? The sea trial with the surveyor did not indicate any unusual noises, although WOT was a bit low (props had some heavy dings in them) and the bottom is in need of a heavy sanding, many divots from layers of chipped paint.
There is whole section in the service manual about pre-load and shim washers on the outlet shaft. If the nut was loose, could it cause damage inside, or is it possible the shim washers may have worn resulting in the nut becoming 'loose'? The machined washer on the nut was also separated from the retaining flange on the nut. I should have used a mirror to inspect the spline, or pulled off the coupling to inspect, but didn't think of either until now. It's not too late yet, but the nut is not reusable.
The procedure calls for preassembling this shaft assembly and torqueing the nut to 50 ft/lbs and taking some precision measurement on the coupling end play. The goal is to adjust the shims to create an allowable endplay while maintaining a certain amount of shaft break loose torque. Then you take it apart, set it aside and continue assembling the rest of the parts, and then torqueing the nut to 220ft/lbs. (the range is pretty wide, 160-250 IIRC).
My torque wrench only goes to 150, so I opted to make it as tight as I could with 24" of breaker bar. The break loose torque is now much higher than it was, easily turning with a 8" socket wench, but too tight to turn by hand (it's slippery from oil and hard to grip). When I was inspecting the shafts a while back, I was able to turn both by hand, but barely. Again, I didn't think to check this again before I left yesterday, and see how they compare now. Since I was not able to turn it from inside, I was only able to get 2 bolts in, so it's not quite a fair comparison till it's torqued tight on all 4.
There is no visible oil on the dipstick, so that's concerning as well. I'm going to drain whatever might be left and study it closely for any metal. I don't think I got more than 1 cup out of the bilge since fall, and some was from the genset, for sure. It holds 2qts. The color of the first round of soaking with absorbent pads seemed a bit off for standard motor oil, but I didn't give it much thought till I had the bilge pumps out and all of it cleaned up, then a distinct red reappeared. The surveyor (and I) disregarded the genset oil situation as the seller stated there was something wrong with it. Way more than he alluded to, but he's not a mechanic.
Short of a tear down, or replacement, any suggestions of what else to look at, or check? I believe there are specs in the manual for pressure testing, but that is an in water test.
John
