OK. I agree that, unless your engine is different from my W50, the oil cooler should not be part of the freshwater coolant circuit. I am trying to figure out how that could happen or be thought to work. Since there are so many potential points of obstruction in this cooling system and (it is tough to see in photos) it is difficult to suggest where the problem is, but I do not like the look of your main exchanger cooler tubes. The lower set of tubes (which is where the initial salt water is first exposed to the hottest coolant) looks a bit crusty. The upper ones look OK in the picture-but you understand the flow is sequential through both—so if either is clogged you are in trouble. Removing the coolers is a bit of a chore but is doable and I would not let this stand in the way of doing the right thing at some point—cleaning it at a radiator shop (and getting it pressure tested) if it has been 1000 or 2000 hours since it was blown out. I replaced my W50 engine 10 years ago with a Yanmar, so my recollections of working on the W50 are a bit hazy, but I had the coolers out at least three times to have them cleaned out in 4000 hours I had it—twice it was essential as there was a heating problem related to them. The first time I took it apart, it was a bitch, but it got easier subsequently. The hardest part is the manifold nuts that are in a very cramped spot, but a crows foot open end wrench is a big help—but I have done it with a regular wrench and some tape to catch the nuts and set them (if you take it off you will understand what I mean). I think you can reuse the manifold gasket at least once—they are not generally crushed or glued on and the torques are “two finger” and not critical—at least once or put some RTU gasket maker on it (by the way, I found the manifold loose when I first did the job). Yes you will have to replace some coolant if you take this apart, but that seems a small price to pay if these are the problem. I realize dumping a caustic chemical in there could maybe do the same thing (seems risky to me—the insides are copper and react to some acids), or maybe flushing it backwards with a garden hose might help, but sooner or later you have the choice of doing this right or running a significant risk of overheating when you do not expect it. If you are doing ocean passages, I think this is a regular critical maintenance item at some interval. You have a different and less fussy cap on your main cooler than some of the W50’s, so that is probably not the problem. Some of them have a cap with a deep groove the divider must be exactly position in or overheating is inevitable (don’t ask what I went through to learn this). One of the reasons I do not like these “marinized” tractor engines is the fact that the marine salt/fresh cooling systems are generally cobbled together with a lot of hoses, connections, dissimilar metals in salt and heat, and a lot of potential points of failure. You can manage it, but it takes active owner involvement in maintenance or there will inevitably be problems. You cannot wait till you have a problem because it will happen at the wrong time. I have stories about how I learned this—it once was near disaster, but I will save them for a different venue. I am telling you this, because you appear to be someone out there actually doing ocean passages and probably depending on your diesel in some out of the way places where failure could be a problem. Marina folks and weekenders can probably just limp to the slip or call the tow boat when they have the predictable overheating that will occur without maintenance of this system. Ray Durkee
|