I thought I'd contribute with a recent upgrade that I'm very pleased with. On this engine, the cooling tank has a very wide neck and cap. The style is reminiscent of 1950's cars and tractors. There's no gauge adapter from anyone I nor my Yard could find to enable pressure testing of the system. There was no way to install an overflow / recovery bottle as the neck and cap design pre-date this function, so excess coolant would leak out the overflow tube and drain down to the pan.
In my instance, I was chasing a small coolant leak, and could not find it for love nor money for 3+ years. Everything looked fine. It only leaked while it was running hard. It only lost a few tablespoons a day.
There is a two-part pipe that connects the tank to the heat exchanger at the back of the engine. The pipe is joined in the middle and at the heat exchanger by pieces of radiator hose, then joined to the tank by an elbow hose. This pipe was corroded, and eventually became my target to stop the leak. The hose parts were old.
I got a fresh parts list from American Diesel (804-435-3107) and shared some emails with Bob Smith [bobsmithadc@gmail.com]. I noticed they sell a kit to upgrade the pressure tank neck to a smaller, recovery style cap with overflow bottle and tube (ADC p/n 810-0405, $65). I chose to purchase their water hose kit (ADC p/n 510-4116 $80). With this kit, I can replace every water hose on the engine as the job comes up. Per advice, I also purchased a new t-stat and gasket. [ Note: if you're not buying a new t-stat, be sure to get a gasket. No body is likely to have one near you ].
Finally, upon taking off that two-part tube, it was pretty badly pitted under the hose connections, so I bought a piece of stainless tube to replace it with.
This is 1 3/4" thin-wall tubing. The short and long piece together are about 20" in length. No local source was found for either steel nor stainless, so I ordered 24" from steve@onlinemetalsupply.com via his eBay site. Cost was $25.33 delivered.
OK...so now on to the job I'm writing about:
1) Drain the cooling system
2) Loosen the hose clamps for the elbow connection to the two-part tube
3) Remove the old overflow tube from the front of the tank so you have more wrench swing. (this tube is discarded during this upgrade)
4) With an open-end wrench, loosen and remove the nuts and lock-washers at the joint of the expansion tank to the head. Be ready to hang your head up-side-down for a while; you can only swing the wrench a tiny bit at a time.
5) With a soft mallet, knock the expansion tank loose, and lift it off the studs on the head.
6) Remove the old thermostat, and clean off the old gasket using care not to drop bits down into the head.
7) Do any other hose replacements you are planning. Deal with your two-part water tube with either a clean & paint job, or replacement.
Either plan to replace your t-stat, or check it in a pan of hot water on your cook stove using a hi-quality thermometer. The opening temp is stamped on the bottom of the wax bulb in Celsius. 84 C = 183 F.9) Clean and wash (and prep-for-painting if you will) the expansion tank.
10) Follow the instructions with the neck kit for replacement. In summary, you cut the old neck with a open-blade hack saw to make a break in the "ring" that is pressed into the tank opening. Once cut, the old neck can be broken out of the tank opening easily. Clean the old epoxy out, sand and prep the surface for installing the new, then using thickened epoxy, glue the new neck in place. Give consideration to which direction you want the new overflow nipple to face, as you can orient this new neck in any position you want.
My only advice for this job is to find a socket that just fits inside the new filler neck. Use this to hammer (or press if you have one) on, rather than taking any chance of damaging that neck. It's a snug fit...so apply epoxy to the new neck and the opening in the tank. Take your time...I assure you the new neck will "cock" in the opening more than once.
11) With the new neck installed, I painted my tank and then installed it over a new t-stat and gasket and mated it to new hoses and pipes to the heat exchanger. (As a retired car tech, I still use a small amount of "form-a-gasket non-hardening" on water system gaskets to ensure they never leak and also are easy to dis-assemble in the future.)
12) Re-fill your cooling system and pressure test. Now any automotive pressure tester will fit your tank neck and work.
13) Find a home for your over flow bottle, mount it and connect it with the supplied tubing.
14) Done!
Enjoy, all.
After 4 years of running all around the coast of Maine (and one trip up the Hudson River to Albany), I'm happier now than every with this wonderful boat!