Hubert S

A clarification regarding my previous message: Reinstalling the seawater inlet hose on the heat exchanger is a delicate task. There are two clamps to tighten—one on the heat exchanger housing and the other on the tubes. If the clamp on the tubes is misaligned, seawater will enter the coolant system, and the coolant overflow will start to leak when the engine is running hot. It is essential that the clamp be perfectly positioned around the edge of the tube sheet and be tightened securely to prevent any internal seawater leakage. You must push the large rubber seawater inlet elbow all the way onto the engine block to properly position the second clamp. It’s surprising that Volvo designed a seawater intake system that’s so difficult to reassemble....It’s not dangerous for the engine if seawater gets into the coolant for 1 or 2 days, but it means you have to drain and replace the antifreeze coolant every time. It’s a long process, and it wastes a lot of time.

Clean your seawater/coolant heat exchanger! I’m writing this post just to share an experience I had last year. On my 2000 HR34, which I’ve owned for 10 years, I had never taken the heat exchanger apart, since the Volvo manuals don’t require maintenance on it, whereas other manufacturers specify that it’s best to inspect and clean it every 3 or 4 years. I noticed that half of the small seawater circulation tubes were clogged with salt and/or lime scale deposits, as shown in the attached photo. My mechanic sent it to a shop that specializes in cleaning and inspecting marine heat exchangers; it came back as good as new, and I now have much better seawater flow. My engine is a 2030 D with S-Drive from the year 2000, which has about 1,200 hours on it.