Johnson V4 140hp 1990 CJ140TLESE Outboard Cooling System Diagram / Repairing Thermostat

s199810

Cadet
Joined
Jun 4, 2020
Messages
14
I guess I want to contribute to this forum as I learned some good stuff here, and others can save time/efford when dealing with the same/similar motor. I cannot say I am 100% correct on this and I am a naval architect desining ship but not a marine engineer neither a mechanic. I just like screw/unscrew something so it keeps me away from cellphone. The link below is a pdf document with photos and detailed illustration in pop-up comments. You need to download it to your computer, hover the mouse over the arrows, lines, and you will see my comments. Through today's test(and other tests) on my outboard by pouring water through the thermostat after the thermostat cover is removed, I think I kind of understand how the system works, so I made that diagram on the fist page (again, I might be wrong). If you have more thoughts, comments are welcome so we can help each other to better understand how it works. I tried to find the original designed cooling system diagram but till now, no luck. As I created the pdf out of photos, it's too large to upload to this website so I put it in Google Drive, it's about 25 MB. For people is cautious on cliking links on Internet, you can copy and paste the link below as you can see it's a legit link to the Google Drive, not a phishing link that hides the real address (I thought I was very cautious but made a mistake once by clicking a link on FB Marketplace) https://drive.google.com/file/d/1q31-tmW3ac8fIxvTsBqyfxmoOrQTuvjr/view?usp=drive_link English is my 2nd language so forgive me if the grammer doesn't sound right to you. Happy boating!
 
Last edited:

dingbat

Supreme Mariner
Joined
Nov 20, 2001
Messages
16,155
I guess I want to contribute to this forum as I learned some good stuff here, and others can save time/efford when dealing with the same/similar motor. I cannot say I am 100% correct on this and I am a naval architect designing ship but not a marine engineer neither a mechanic. I just like screw/unscrew something so it keeps me away from cellphone. The link below is a pdf document with photos and detailed illustration in pop-up comments. You need to download it to your computer, hover the mouse over the arrows, lines, and you will see my comments. Through today's test(and other tests) on my outboard by pouring water through the thermostat after the thermostat cover is removed, I think I kind of understand how the system works, so I made that diagram on the fist page (again, I might be wrong). If you have more thoughts, comments are welcome so we can help each other to better understand how it works. I tried to find the original designed cooling system diagram but till now, no luck. As I created the pdf out of photos, it's too large to upload to this website so I put it in Google Drive, it's about 25 MB. For people is cautious on cliking links on Internet, you can copy and paste the link below as you can see it's a legit link to the Google Drive, not a phishing link that hides the real address (I thought I was very cautious but made a mistake once by clicking a link on FB Marketplace) https://drive.google.com/file/d/1q31-tmW3ac8fIxvTsBqyfxmoOrQTuvjr/view?usp=drive_link English is my 2nd language so forgive me if the grammer doesn't sound right to you. Happy boating!
A 6 cylinder but a bit more detailed1692531867309.jpeg
 

dingbat

Supreme Mariner
Joined
Nov 20, 2001
Messages
16,155
Oops
Here is the one I meant to post
 

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