6-71n Mixing Elbows

[Jammin']

I received a pair of stainless steel exhaust elbows from Johnson & Towers for my 6-71's to replace what appear to be original cast iron elbows. There are no indications that I have a problem with the existing elbows, but if these really are supposed to have a 5-10 year service life, then it's time. If the old ones can be cleaned up, they will be good spares. The new water inlet has a 90* elbow whereas the original goes straight in. I was going to have the inlet reworked to match the existing, but a simpler solution would be to use a rubber 90* elbow. I don't think they are any clearance issues under the hatches with the added height. Am I missing something?

 

[MadHatter53]

What did they cost ?

 

[Jammin']

What did they cost ?

Sent you a PM.

 

[SEVEN]

Seems as if you have covered it all. Should not be any major issues as long as you have the room for the extra elbow. They sure are pretty. Good luck.

 

[kelpy]

When mounted up, make sure that the water drains completely out of the elbows when the engines are off.

 

[Jammin']

When mounted up, make sure that the water drains completely out of the elbows when the engines are off.

Since the elbows will be higher, that shouldn't be an issue. I sure hope it fits!

 

[scottinsydney]

Hi Robert,

What is the sensor?

Scott

 

[Jammin']

Hi Robert,

What is the sensor?

Scott

It's an Aqualarm cooling water flow detector. I'm planning on putting in a multifunction alarm panel with flow and exhaust temperature alarms among other things. For me, over heating the engines would be a financial disaster.

 

[Cricket]

Oh wow, like the idea but not the placement with PVC pipe and lots of heat at that location. Always thought those were supposed to be on the suction side of the water pump????

 

[scottinsydney]

Nice.

The cost of a single engine replacement is about 1/3 the value of my boat. It would not be a good thing to happen.

About a year ago I took the boat up to 1500RPM for about 20 minutes. The Systems Monitor alarm beeped and showed portside Exhaust temperature.

About a month later I replaced both engines' impellers. Port side impeller was shot but still showing a decent flow at idle when I did the checks after starting.

I'd like to incorporate flow alarms too. At the same time I would plumb in a ball valve and T piece before the mixer elbow to be able to do intercooler and heat exchanger cleaning with Barnacle Buster.

 

[Jammin']

Oh wow, like the idea but not the placement with PVC pipe and lots of heat at that location. Always thought those were supposed to be on the suction side of the water pump????

The instructions say the flow detector can be installed between the engine raw water discharge and exhaust raw water overboard. How hot is the cooling water at this point?

Now that I've gone back and read the instructions again, it says the detector "should" be installed with the tower perpendicular to the ground, not to the side. I'm not sure there will be room for that sticking up. It depends on whether "should" means "must".

 

[oscarvan]

It depends on whether "should" means "must".

According to the FAA's enforcement branch (which is wholly unaccountable).... usually it does. Doesn't apply here of course. But if it was me I would. Keep the variables to a minimum.

 

[Jammin']

According to the FAA's enforcement branch (which is wholly unaccountable).... usually it does. Doesn't apply here of course. But if it was me I would. Keep the variables to a minimum.

I found this:

"The sensor needs to be perpendicular to the ground. It can be angled slightly to one side or the other . If it is angled a lot or parallel to the ground, you may experience unsatisfactory results. Only installation and test will tell. When the detector is angled, gravity starts affecting the paddle."

But the paddle is spring loaded so it's a little hard to figure how that will affect it.

 

[oscarvan]

Proceed at your own risk.

 

[KPTIM]

Consider a non-invasive point of contact marine exhaust temperature sensor.
It mounts directly to the stainless elbow. You do not have to have a bung welded in the elbow.
This would be similar to the ones originally on the elbows stock from Hatteras (at least on mine and others I have seen)..
A lot of them out there to choose from.
They are a lot more elegant looking and have no moving parts. Just a bi-metalic switch.
I think the one pictured has a paddle wheel sensor and will require some maintenance.

There are also marine ones that are designed to strap onto the exhaust hose.

 

[Scarlett]

I have the Aqua Alarm flow meters, don’t make it to difficult, install as close to parallel to the floor. Best place is in the hose between the outlet of the heat exchanger and where that hose goes into the exhaust. Cut the hose and put it in will work just fine. Side benefit of these flow alarms is you don’t have to go look and see if you have water flow out the exhaust. Great for us lazy people. If you search the forum for flow alarms there is a picture of mine installed. John

 

[Jammin']

I'm having the elbows cut off and straight inlets welded on. It will solve all the issues. It turns out that these were made by DeAngelo for Johnson & Towers. I found that out trying to track down the alloy.

 

[dsharp]

I’m glad that you made that decision. Those 90’s are major restrictions.

 

[Top Hatt Craig]

Our boat uses the 90s and the water inlets bolt on, I talked to J&T a while back about getting the inlets as ours are heavily corroded inside. The price was eye popping but now I’m thinking it was for the whole assembly?

 

[Cricket]

J&T is just reselling parts with a big markup added that a vendor made for them such as D'Angelo or Marine Exhaust Systems from Florida. Go direct to save some $$$ and also get exactly what you need. Also, I'm pretty sure Marine Manifold on Long Island made exhaust parts for them too. Many of the cooling components came from Lenco, also on Long Island.
J&T in Mt Laurel NJ was an insane place to visit back in the 80's, engines and parts bins as far as you could see with teams of installers removing DDA original parts and installing the J&T components. They would run the engines before they painted them and they must have been 15 different colors. We needed some obscure part for our 8v92's which they knew they had, just not exactly where except in 3 shipping containers out back. They told us if you can find it you can have it, took 2 of us maybe 3 hrs before we found it. .