Draining fresh water and sea water on ford lehmans

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GrandWood

Senior Member
Joined
Jul 16, 2022
Messages
186
Hello guys and girls, I’m trying to find the best way to drain both sea water and fresh water from the cooling systems to replace both coolers and the heat exchangers on my Lehmans engines. Have an odd set up as port is a 120, and starboard is a Dorset 80. I’ve looked online and can’t seem to find a drain for either. I had a stuck open thermostat on the Dorset, which I replaced yesturday stuffing a massive amount of paper towels around the bottom of the tank. I tried the drain on the heat exchanger and some came out, seemed to be what was in it, tank level didn’t go down. Ended up pumping out the tank best I could, then the paper towels and was able to change thermostat.

Is there a single drain plug that drains the system or you have to drain each component. Online picks haven’t helped as I can’t find what’s shown in picks, and when ever I find a vid to change water pump or other cooling component they never show how they drained the system.

Thanks
Joe
 
There's an NPT coolant drain plug on the port side of the 120, from memory it's pretty close to the water temp sensor. I replaced the plug with a drain valve to make the job easier.

For the raw water there's no drain port - the system is all external to the engine, and the volume of seawater is pretty small. When I swapped the heat exchangers I just pulled the system apart one piece at a time.
 
There's an NPT coolant drain plug on the port side of the 120, from memory it's pretty close to the water temp sensor. I replaced the plug with a drain valve to make the job easier.

For the raw water there's no drain port - the system is all external to the engine, and the volume of seawater is pretty small. When I swapped the heat exchangers I just pulled the system apart one piece at a time.
Thank you sir, much appreciated
 
Have an odd set up as port is a 120, and starboard is a Dorset 80.
You have mismatched twins? How is prop speed balanced?
 
Have an odd set up as port is a 120, and starboard is a Dorset 80.
You have mismatched twins? How is prop speed balanced?
I was told there matched by the fuel Injection pumps. I really dont know how you would do that, turn one down, or turn one up. Still learning many things about this boat. Owner stated in the ad that there was a 120 and a 135, which was wrong. When I looked at the boat, they both looked the same, and the starboard engine is green, which is original to the boat. Took pics and Brian at American diesel told me it was a Dorset.
 
80 is a 4-cylinder, has 4 injector lines coming off the top of the injector pump. 120/135/140 is a 6-cylinder, has 6 lines off the top.
Mixing a 6 and a 4 would be unusual.
A 4 or a 6 can be either a Dorset or a Dover.
A 120 and a 135 mix is not too unusual in the 1983-1986 range. I was told that some 120 warranty replacements were made with 135s after production stopped on the 120s.
 
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