Went down to the boat on Wednesday to see if I couldn't track down our 'overheating' problem with the diesel engine. Started with the obvious places, the water intake filter, and then opened up the impeller to take a look at it. The impeller showed a little bit of wear, but wasn't completely toast, so I don't think that was the problem. To be on the safe side, I took it down to the ship's store to get a new one (as long as I had it opened, I figured I might as well replace it and keep the old one as a spare). I seem to remember buying a replacement once before, but couldn't seem to find it anywhere.
The next step was the manifold and cooling system. I located the manifold and cooling tank thanks to the engine manual, and opened up the cap and stuck my finger inside to check the coolant level. It was bone dry. This could very well be the culprit. The overflow tank was full, but the manifold itself didn't seem to have any coolant in it. I checked with a few people at the ship's store, and they confirmed that, yes, it should have coolant in it. So, when I bought the impeller, I also picked up a bottle of engine coolant and a funnel ($65 bucks so far -- the impeller alone was $40).
I went back to the boat and put the impeller back together and then put some coolant in the manifold. At this time I noticed that the impeller cover was leaking (wonder if I should have bought some gasket seal while I was there), and took it apart once again to double check that I had put it together correctly. The second time I managed to tighten the bolts a little more snug and the leaking was much less, but still there. I decided to try running the engine for a bit to see if the overheating problem was still there.
I ran it for just a few minutes, and got spooked when the temperature gauge wasn't registering anything at all. It was possible that I didn't run it long enough, but I was worried that there was something wrong with the thermostat and I wouldn't know if the engine was overheating or not, if it stopped working. I figured I better wait and bring Terri out here to monitor the temperature gauge while I watched the coolant levels. In the meantime I thought maybe I'd try tightening those impeller cover bolts one more time to see if I couldn't stop that slow drop. Bad idea. The first bolt I tried tightening twisted off and broke off inside the impeller cover. At this point I threw in the towel and decided to schedule a maintenance visit from the boys at the marina.
If it was the coolant in the manifold being dry, though... why did it not get checked at our launch? Is this part of what we pay for winterizing the engine every year? I wonder how many of our 'problems' we've had since buying this boat have been caused by oversights by the marina crew at haul out and launch? Off the top of my head, I'm remembering the backwards furling gear on our first launch, the dip stick not in place on that first launch (which caused us a major oil spill cleanup that first summer), the bilge pumps not being wired to the batteries for the first few years (which led to our boat sinking in the slip when the propeller packing failed), cosmetic damage caused at one of the haulouts when one of the blocks got caught either between the wall and the boat, or one of the haulout straps and the boat, and this year, when they once again forgot to hook up our bilge pumps to the battery and then tried to charge us for the service call when we asked for it to be done.
Of course, we've been the cause of a few of the problems, ourselves. I'm remembering the 'dead battery' mystery of a few years back that ended up being our fault for not hooking them up properly (the one year we winterized our own batteries and reinstalled them ourselves). This boat ownership has certainly been a steep and expensive learning curve. I wish I was more confident at doing my own repairs. But I'm trying. At least this time I managed to become a little more familiar with the engine, and managed to locate the manifold and the thermostat housing (the thermostat was going to be my next item on the list, if the manifold wasn't the problem)
Steeling myself now for the engine repair bill.