Impeller replacement with help from the cat
No matter where we are or what we are doing on the boat, we have our curious, little helper who tags along! He is always exploring the many small spaces he can fit into or the holes he can squeeze his paw through–and that means we have to watch him! Or like good ole Curious George, he could get into trouble!
Hot, hot engine
Our Universal diesel engine was running a little hotter than normal: 190 degrees F compared to 160 degrees F we’d prefer it to be at. Our thirty-year-old engine is the original our 1986 Catalina 30 was built with, so we are monitoring her and giving her extra care each time she runs. Wait–that sounds like Schnitzel! We have to monitor him and give him extra care too!
Time for an impeller change?
We had not yet changed the engine’s impeller, and Damian wondered if replacing it with a new one would be a factor in lowering its running temperature. You may be asking yourself the same question I did, which is: “Why does an engine need an impeller?” Short answer: to cool the engine down.
What is an impeller’s job?
Unlike car engines that cool with anti-freeze through a closed system, boat engines cool themselves with sea water that runs through a pump and enables the engine not to over heat. Captain Dave taught me in my ASA 104class that the raw water pump uses a small rubber vaned impeller to suck water from the bay to the engine and thus circulates the water through a series of valves through the exhaust bringing the engine’s temperature down significantly. This process constantly takes place every time the engine is running. Since impellers are made of rubber like tires, they experience a lot of wear and tear and need to be replaced on a regular basis. When they crack, real trouble is inevitable.
Replacing the impeller with Booh-bah
First, Damian located the raw water pump and took four screws off of it. And then there’s Booh-bah. The plate came off and behind it was the rubber impeller. Booh-bah (our cat) poked his head into the engine compartment to get a better look. Next, Damian used a flat head screw driver and removed the snap ring, which held the impeller on the shaft. He used needle-nosed pliers to pull the impeller off, because the impeller had melted over time around the metal shaft. Again, Booh-bah tried to sneak his fury body back into the tight-open space, and Damian gently pulled him out so that he would not get stuck or hurt. After examining the removed impeller, Damian discovered that nothing was really wrong with it (no cracks)–at least not visibly. And the cat took a look for himself too. Damian decided to be on the safe side and replace the impeller with a new one anyway.
From reading and researching engine care, Damian knew that having spare impellers on board was vitally important. So he took one of the new spares, which he keeps in a compartment under our chart table, and slathered the rim inside the impeller with Vaseline so that it would have less friction when it spun around the shaft. Booh-bah sniffed the new impeller and decided it was time to take a break, so he laid down beside Damian to be entertained by the rest of the replacement process. Then Damian pushed the impeller back into place and re-screwed the pump plate back over top of it. We were back in business! From what we could tell, the impeller replacement did not affect the engine temperature. We are still searching for the cause!