Purpose and function of the raw cooling water mixing tee? - SailNet Community
 
LinkBack Thread Tools
post #1 of 8 Old 06-22-2011 Thread Starter
Junior Member
 
Join Date: Feb 2011
Posts: 23
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
 
Purpose and function of the raw cooling water mixing tee?

I have a 5411 raw water cooled engine and often wondered what may be the purpose and functioning of the mixing tee immediately atop the water intake shut off valve. Imagine this tee as having 3 arms or directions: one draws water from underneath the hull thru the shut off valve; another is connected by hose to the cooling water pump inlet; and the third is connected by hose to the bottom side of another tee just below the thermostat housing that is attached to the exhaust manifold.
Can anyone shed some light on this please?
confused Bateau25
Bateau25 is offline  
Quote Quick Reply Share with Facebook
Sponsored Links
Advertisement
 
post #2 of 8 Old 06-22-2011
Senior Member
 
JimsCAL's Avatar
 
Join Date: May 2007
Location: Glen Cove, NY
Posts: 2,882
Thanks: 2
Thanked 76 Times in 70 Posts
Rep Power: 9
 
The diagram in the manual describes this pretty well. When cold, the water recirculates back from the thermostat back to the pump suction. Only a little goes out the exhaust. Once the engine comes up to temperature (140 F) the thermostat sends more water out the exhaust and less is recirculated. This approach is much better than those that bypass the engine entirely until it warms up as it equalizes the engine temps much better during warmup. One thing to keep in mind - don't try to run the engine without a thermostat - it will overheat. Without the restriction provided by the partially closed thermostat, it just stays in recirculation mode.
JimsCAL is online now  
Quote Quick Reply Share with Facebook
post #3 of 8 Old 06-23-2011
Senior Member
 
Omatako's Avatar
 
Join Date: Sep 2003
Location: Auckland New Zealand
Posts: 2,558
Thanks: 1
Thanked 33 Times in 30 Posts
Rep Power: 12
 
The water pump that circulates water thru the engine (not the raw water pump) pumps directly into the engine. When the engine is hot (normal) the water passes thru the thermostat and heads for the exhaust manifold cools the manifold and then on to the mixer and cools the exhaust system (including the rubber pipe).

When the engine is cold the thermostat stops water leaving the engine and going to the manifold/exhaust. In this phase of engine warm-up, the water from the raw water pump has to bypass the engine to cool the exhaust which is very hot from the very first revolution.

If the raw water does not bypass the engine while the thermostat is shut, the rubber pipe on your exhaust is toast.

Hope that helps.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

__________________

"Two possibilities exist: Either we are alone in the Universe or we are not. Both are equally terrifying."

Arthur C. Clarke
Omatako is offline  
Quote Quick Reply Share with Facebook
post #4 of 8 Old 06-23-2011
Senior Member
 
JimsCAL's Avatar
 
Join Date: May 2007
Location: Glen Cove, NY
Posts: 2,882
Thanks: 2
Thanked 76 Times in 70 Posts
Rep Power: 9
 
What Omatako is describing is typical of many raw water cooled engines but not the Universal 5411. I lived with one for 20 years and know the cooling water system like the back of my hand.
JimsCAL is online now  
Quote Quick Reply Share with Facebook
post #5 of 8 Old 06-23-2011 Thread Starter
Junior Member
 
Join Date: Feb 2011
Posts: 23
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
 
I agree with JimsCAL. The 5411 (and the M15) is unique in that it is directly raw water cooled without a heat exchanger and only one water pump.

According to the manual, water circulates thru the block and heads out to the exhaust manifold to cool down the exhaust ports and then thru the thermostat, if its open, and onto the exhaust mixing elbow, to the muffler and out the transom. If the thermostat is not open or only partially open, then most of the circulated hot water goes back to the mixing tee where it is supposed to mix with fresh cold water and then go thru the pump again for another cycle. Is this correct?

I also noticed that as the engine warms up more water comes out with the exhaust gases via the open or partially open thermostat, but at the same time the raw water pump starts getting hot as apparently it begins to circulate some of the hot water! This confuses me as I thought the hot water coming back to the tee should then mix with fresh cold water to cool it down before it is sucked thru the pump for the next go around so that the pump does not get too hot. But in my set up, the pump gets too hot to touch as the engine reaches operating temperature! Is this normal? I am concerned that the water pump may not be designed to pump hot water so this could be a time bomb? Anyone could kindly shed more light here or please correct my dumb notions?
Bateau25 is offline  
Quote Quick Reply Share with Facebook
post #6 of 8 Old 06-23-2011
Senior Member
 
JimsCAL's Avatar
 
Join Date: May 2007
Location: Glen Cove, NY
Posts: 2,882
Thanks: 2
Thanked 76 Times in 70 Posts
Rep Power: 9
 
Bateau your understanding of the system is correct. When up to temperature, the water recirculated back to the pump should be about 140 F or so where it mixes with some cold water from the seacock. The pump should be hot, but not too hot to touch. What does your temperature gauge read? If over about 150 F your engine is running hot.
JimsCAL is online now  
Quote Quick Reply Share with Facebook
post #7 of 8 Old 06-23-2011 Thread Starter
Junior Member
 
Join Date: Feb 2011
Posts: 23
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
 
typically I get around 145F to 155F depending on how much I push her along. If it is just idling, the temp would hover at about 135F. Well if the pump normally gets hot then perhaps I am worrying for nothing! But it does get too hot to hold for more than say 5 seconds with bare hands. I only hope the rubber impeller does not melt at this temperature!

Many many thanks JimsCAL for the clarifications - sure were extremely useful!
Bateau25
Bateau25 is offline  
Quote Quick Reply Share with Facebook
post #8 of 8 Old 06-24-2011
Senior Member
 
Omatako's Avatar
 
Join Date: Sep 2003
Location: Auckland New Zealand
Posts: 2,558
Thanks: 1
Thanked 33 Times in 30 Posts
Rep Power: 12
 
Quote:
Originally Posted by Bateau25 View Post
I agree with JimsCAL. The 5411 (and the M15) is unique in that it is directly raw water cooled without a heat exchanger and only one water pump.

According to the manual, water circulates thru the block and heads out to the exhaust manifold to cool down the exhaust ports and then thru the thermostat, if its open, and onto the exhaust mixing elbow, to the muffler and out the transom.
And what cools the exhaust gas into the elbow if the thermostat is not open?

Quote:
Originally Posted by Bateau25 View Post
If the thermostat is not open or only partially open, then most of the circulated hot water goes back to the mixing tee where it is supposed to mix with fresh cold water and then go thru the pump again for another cycle. Is this correct?
So the water that is headed for the thermostat is first heated by the exhaust manifold and opens the thermostat before the engine reaches operating temp? That is indeed unique. And by the sounds of it the raw water pump has engine temp (hot) water running over it most of the time? That must be good for the rubber impeller. Tell me it has a rubber impeller!!

Sorry Jim, I wasn't contesting your opinion just trying to add to it but then I'm obviously not schooled in the odd way that 5411 is engineered. Maybe I'll just withdraw from this discussion.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

__________________

"Two possibilities exist: Either we are alone in the Universe or we are not. Both are equally terrifying."

Arthur C. Clarke
Omatako is offline  
Quote Quick Reply Share with Facebook
Reply

Quick Reply
Message:
Options

By choosing to post the reply above you agree to the rules you agreed to when joining Sailnet.
Click Here to view those rules.

Register Now



In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.


User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Similar Threads
Thread Thread Starter Forum Replies Last Post
Fresh Water cooling water dirty brown sailak Gear & Maintenance 17 07-31-2009 11:52 PM
Raw Water Cooling - No Water Coming Out montenido Gear & Maintenance 20 01-21-2009 04:16 PM
Connecting raw water cooling to water heater Northeaster Gear & Maintenance 18 04-28-2007 06:11 PM
Refrigeration -Using the water tank as a cooling water source HenryRusty Gear & Maintenance 7 03-29-2007 12:14 AM
convert from sea water to fresh water cooling.... john232 Gear & Maintenance 3 02-16-2004 03:44 PM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome