Plumbing for dripless shaft seals

[cwiert]

I have a question regarding dripless shaft seal plumbing. Currently, I only have a hose going from the oil cooler on the 3116 to the shaft seal on it's respective side. No double protection. This past summer, my stbd hose got clogged, and I melted the stbd shaft seal housing due to lack of water. So now I'm trying to avoid that from happening again. I replaced the housing for the stbd side with one that has inputs for 2 hoses. My port side still only has 1. My question is, do you think I need to add 1-way check valves anywhere in the plumbing? I'm worried that if I lose one engine, will the other engine be forcing water back into the stalled engine? And if so, would that be bad?

Here's a diagram of my proposed and current set up.

 

[PlayDate]

Sorry to hear about the line clogging. Without overthinking the issue, most of the manufacturers recommend a single t fitting on each of the supply lines to the seals. A crossover hose is then attached between the two t fittings. There isn't a lot of pressure on the supply hoses and the hose is relatively small. I have never heard of one causing a problem back flow issue into a engine which is switched off. If you are concerned about running on one engine for an extended period, you can always place a small, manual flow valve on the crossover hose.

 

[fwebster]

Trying to look ahead a ways, at some point you will need to replace the old (1-barb) seal with the new design. At that point, you will just connect the 2 seals with t he 2nd barb on each seal. I would run the line from the 2nd barb on the new seal to the old seal, add about 18" of hose and install the "T" close to the old seal. That way you can just clip t he crossover hose and connect it to the second barb when you eventually do replace the old seal.

 

[rondds]

I had set up my own cross-over up on my boat. I called Tides and they said you can T off no more than 12" from the shaft log. You may want to call them and double check this out for sure. They are very helpful.

See HERE for my story with a melted dripless. If you haven't figure it out already, you need to ask WHY there was an occlusion that caused the meltdown. And you should probably check the other side for good flow, just to be sure it doesn't happen there too.

Also, what Frank said. If you are due for a replacement, the new design has two nipples on the dripless.

Here's another link on that whole process if you're interested.

http://clubsearay.com/showthread.php/64474-Replacing-Dripless-on-a-2001-380DA?highlight=

 

[cwiert]

Thanks for the replies. So, because I like pictures, is this what you guys are talking about? Should I do something like this (at least until I replace the port seal with a new double nipple version)?

Sent from my iPhone using Tapatalk

 

[PlayDate]

Yes.

 

[dpmulvey]

I'm not a big fan of Dripless Shaft Seals because of the failure mentioned above. The cross-over you depict will work. If you are going to change out a seal unit, consider an oil bath system. To me, next best thing to a stuffing box.

 

[rcknecht]

Mine was changed as you depicted in your first diagram...

 

[rondds]

That's what I did. Originally. Then the other one fried and I had two with the new style (double nipple). STRONGLY suggest you run the engine at the dock and stick the hose that goes to the dripless in a bucket and evaluate the flow. Do one engine at a time and if you're ambitious, then check the crossover (once it's all done and installed).

 

[cwiert]

That's what I did. Originally.

Which version did you do originally? The diagram in my original post, or the one in post #5? And yes, I will definitely be doing a lot of testing. once I get it set up.

 

[rondds]

I had set up what you sketched in post #5.