Manzanita’s engine, a Universal M25 diesel, had well-known temperature issues from Day 1 of our involvement. The heat exchanger and the raw water pump were both green with corrosion.
So after we got back to the Bay Area, we set to work getting these pieces. Each was available online, and could be shipped to us for twice the cost of the piece itself. Charles called around to Bay Area distribution companies, and was able to find one in Fairfield who would let us come pick it up for no extra cost.
So, I took the long drive to Fairfield for the parts. When I got back, I immediately set to work getting off the old raw water pump. Once it was off, which was an exciting process in itself, I watched a few tutorials about putting the replacement on. One of the videos I watched mentioned briefly the issues with Sherwood replacements for the Universal M25 Diesel Engine.
Perfect, exactly what we bought. I spent the next hour on the internet, and found out that Sherwood impellers have a tendency to fail, and need to be replaced more frequently than other replacement options. This had not been mentioned in any of the things I had read, so finding it buried in a YouTube tutorial was surprising. But, we decided to get the Oberdorpfer raw water pump and impeller instead. After a week of waiting for the new part to come in, I drove back to Fairfield to get the Oberdorpfer.
Installation was exciting, and some of the bolts were really hard to get off, but ultimately it went smoothly. With some elbow grease and help from my uncle, and tools from Charles’ father, we were able to get the new heat exchanger and raw water pump installed in just 2 days.
After installing the new parts, we did the requisite oil change and looked at the coolant. We topped up, and ran the engine again, which was still running hot. It took us a few more days to realize that the coolant manifold was closed, because that manifold is hidden behind the bulkhead.
The manifold has three positions. #1 is to send the 50/50 water/antifreeze mix to the the hot water heater, #2 closes the heater lines buy still circulates in the engine, and #3 is all closed. This made us think the thermostat had failed and was not opening when in reality the manifold was just closed. Once we got it into the proper position, we were ready to jump on the sailing season.
Since these projects, and with regular maintenance, the engine has been very consistent – my favorite thing in an engine.