Add Tempature sending unit to a Classic Fifty by Mercury

Kevin60181

Seaman Apprentice
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Jun 30, 2012
Messages
44
I have a Mercury Classic Fifty. Told is was a 1984, but the serial number A950272 and it's a 4 cylinder says it's a 1986.
I was thinking about adding a temp. sending unit to this engine. I see a small one in the Sierra catalog, part number 18-5896. It's 1/8" - 27 NPT threads. That should be pretty easy to drill and tap.
The question is where? or does anyone know of a plug that could be removed and used.
I'm open to any ideas????
I also see a nice selection of gauges, any one any better than the other?
 

Kevin60181

Seaman Apprentice
Joined
Jun 30, 2012
Messages
44
Has some useful information. Thank You!
Different engine. Looks to be a 6 Cyl., were mine is an outboard 4 cyl. Best bet is for me to slow down and think this out over time.
All thoughts, information, plans and ideas welcomed.
When I start this project, I'll be sure and take pictures along with video so it can be shared on You Tube with Iboat fans.
My new water pump and prop arrived from Iboats Saturday. So I'll get busy with that and take another look at this project during the install.

What's up with this forum? I keep posting pictures to my post and the Tags & Pictures disappear a few minutes later.
 

sam am I

Commander
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Jun 26, 2013
Messages
2,169
Sure, just didn't think you'd want/need to be drilling/taping holes and yes, it was a V6 w hopefully some similar features you can get some ideas from ...............

The forum? Oh, it wasn't broke, so they "upgraded" errrr, downgraded it about a month ago, owners kids bored I think :facepalm:. The site is free to participate in tho and most certainly there's no potential revenues that come from this .:lol: So no complaining now.....

Ahhhh yes, Groupthink is such a wonderfully(and cheap!) predictable tool eh?

At any rate, some days it doesn't work and others, it doesn't work less. They're working on it tho, hang in there "they" are informing us....lol. So just relax and http://www.youtube.com/watch?v=y6Sxv-sUYtM clap along.


Pictures of the motor would be nice tho, I'd be interested in seeing what we are working w here. Some here use links to like Photobucket and the like as a work around.
 
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Kevin60181

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Joined
Jun 30, 2012
Messages
44
No Title

Here's 6 close ups of the engine. There is a picture with me pointing at a water outlet with a pen.
I was thinking maybe switch that with a few fittings to pass over the temperature sending unit then continue the rubber hose.
That's the hose that shoot the small stream of water to let you know the pump is working.
I sure hope these upload...
I used this forum a number of years ago to get some help with my 1st engine, a 1956 Fastwin 15HP by Evinrude. Those guys where a great help. I also made a few videos with their help and mentions Iboats.com. They are on You Tube https://www.youtube.com/watch?v=ga1Cjymj6ms

I was thinking I was doing something wrong..... Still the best sight out here!
 
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Kevin60181

Seaman Apprentice
Joined
Jun 30, 2012
Messages
44
No Title

Has some useful information. Thank You!
Different engine. Looks to be a 6 Cyl., were mine is an outboard 4 cyl. Best bet is for me to slow down and think this out over time.
All thoughts, information, plans and ideas welcomed.
When I start this project, I'll be sure and take pictures along with video so it can be shared on You Tube with Iboat fans.
My new water pump and prop arrived from Iboats Saturday. So I'll get busy with that and take another look at this project during the install.

What's up with this forum? I keep posting pictures to my post and the Tags & Pictures disappear a few minutes later.
 

Kevin60181

Seaman Apprentice
Joined
Jun 30, 2012
Messages
44
No Title

Has some useful information. Thank You!
Different engine. Looks to be a 6 Cyl., were mine is an outboard 4 cyl. Best bet is for me to slow down and think this out over time.
All thoughts, information, plans and ideas welcomed.
When I start this project, I'll be sure and take pictures along with video so it can be shared on You Tube with Iboat fans.
My new water pump and prop arrived from Iboats Saturday. So I'll get busy with that and take another look at this project during the install.

What's up with this forum? I keep posting pictures to my post and the Tags & Pictures disappear a few minutes later.
 

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Kevin60181

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Jun 30, 2012
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Looking at the picture below. the one where I'm pointing with a pen. That is an out flow tube that connects to a hose, which sprays the hot water out back into the lake. The one that lets you know the water pump is working.
How about hooking that to a larger tube so the how water from there flows over the temperature sending unit???
Just not a lot of room to play with in that area.
I see my pictures stayed on my last posting. :adoration::cheer2:
Finished installing my new Water Pump from Iboats.com
 

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sam am I

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Don't see why not.

I don't know that block's coolent flow path, but your inline hose exit point idea is properly better than drilling a hole in the block perhaps not knowing what on the other side.

You could always use a no touch thermo gun(or other similar but accurate means) as the reference and compare the two as the thing heats up. Shoot the block while watching your new gauge, if they're both track within like 5% or 10% for example of each other from a cold start up to run temp, then there ya go, who cares what the path is as long as that water temp reflects'ish the block, yer good to go. If not, we'll cross that bridge if it comes
 
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Kevin60181

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Jun 30, 2012
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44
Did it in line with the pee hose. Getting a temp around 125 to 130 degrees.
I'll try and up load a few pictures.......
 

Kevin60181

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Hope these post!
 

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roscoe

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Did it in line with the pee hose. Getting a temp around 125 to 130 degrees.
I'll try and up load a few pictures.......



So, what kind of temp do you expect to see if there is no water flow?

It could read lower, even though the head temp would be climbing.

I would want my temp sensor directly on the head, or in the water jacket surrounding the head.
 

Kevin60181

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Better safe than sorry... I didn't want to drill and tap into the CYLINDER BLOCK COVER ASSEMBLY, not knowing what behind it.
This was the simplest and safest way to get this done.
Sometimes something close is better than nothing......
It does work!
 

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Kevin60181

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Do to a Cylinder Block Cover leaking gasket , I found the perfect place to mount the sending unit.
Right by Cylinder #3.
 

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