Hooray! New higher thermostat for Universal 5432

I can barely contain my happiness tonight for having solved a seemingly minor problem with the standard thermostat for the Universal 5432 on Aeolus. As some will be aware, the only factory thermostat available for this diesel is set at 160 degrees. Although many folks on sailnet and other places have complaints about their 5432's running hot, I have always had the opposite problem on Aeolus. In fact, when I first purchased her, she wouldn't come up above 120 degrees and I knew she must have had a thermostat stuck open. Sure enough, I replaced the original one I inherited with the standard factory model and ever since she has taken her time getting up to 160 and then sits like clockwork right there.

No matter how hard she was pushed, she never budged off of 160. Now, also as many will know, this is fine if your diesel is raw water cooled as it prevents undue salt crystal formation. However, as a fresh water cooled engine, this is far too low. At 160, the diesel will build up carbon in the cylinders and around the valves and generally not burn cleanly due to the low temperature. In my case this is especially true because I run a high % biodiesel which has a lower flash point and benefits from a higher combustion temperature. Calder et. al. talk about this.

Anyway, I've been on a long slow search for a higher engine temperature. I began by putting a ball valve into my water heater line thinking that by taking this out of the circuit I could generate a higher engine temperature. No luck. Still stuck on 160 max temperature. My cooling system is really, really efficient it seems.

So since then I have been wanting to swap out my standard thermostat with one of a higher temperature. The 5432 engine manual I have says the optimum operating temperature is between 170-185. Then why do they only make a 160 thermostat???? Here is where the story gets good.

Loving to solve these problems, I pulled my old thermostat out, took it home and began some online research. I found online that I could get one of the same size and shape with various temperature ratings. Anything from 160 to 180 to 195. Yippee, I thought. Knowing from experience how things ordered online don't always size up right, I decided to try my local auto stores armed with knowledge of what cars used this same size thermostat.

I went into my local NAPA store and was mistaken to think they might actually enjoy something a little more challenging and interesting than fetching parts off the shelf that match what their computers tell them. The owner of the store helped me and early on I could tell that he was less interested in finding me an answer than trying to tell me I was wrong to even search for one. The arrogance and laziness of his work with me was so disappointing, as I would have thought a local guy who wasn't even busy would find some fun in matching my thermostat with one he had on his shelves in a higher temperature range. After 20 minutes spent mainly listening to him tell me that he couldn't find one and implying I was foolish to be bothering him with this quest, I left both annoyed and amused.

Later that day I walked over to our local Car Quest parts store, which is a much smaller shop here in Friday Harbor and had a wonderful experience. From the outside the place looks run down, and even when inside the walls are lined with merchandise that hasn't sold in the last two decades, but the guy behind the counter solved my problem quickly and easily. He took my old thermostat, measured it with his calipers, pulled out his Car Quest thermostat book, matched the specifications with one of the pictured thermostats exactly, and immediately had the part numbers. He turned around, walked back to his shelves, and two seconds later came back with my 195 degree thermostat for about $6.

I can't describe how happy I was to have this guy do such a simple and good job of solving my problem, with nothing but a helpful attitude. I was in and out in maybe 5 minutes.

Tonight I went to Aeolus and installed the new thermostat. I then ran her in gear at the dock (yes I have direct injection cutless bearing cooling) and watched her come up to temperature. Slow at first, but then she rose steadily past 140-150-160-170!!-180!! to 190. Hooray!

No matter how hard I ran her she wouldn't budge above 190. Even though this was at the dock, my previous long experience with Aeolus tells me she is not likely to go higher when running hard against the strong currents around here either.

To have her run steadily now at 190 relieves all my concerns about carbon build up. I can just see the carbon burning off the piston rings and the valves. For anyone else out there with a similar problem, I hope I have saved you some trouble by telling you that the 195 degree thermostat for you is Car Quest model #31979 which is made by Stant. The 180 degree model # is 31978. FYI, the thermostat shown in the picture is actually the old 160 model, which differs only in having those small holes along the flange.