They don’t call it “preventative” maintenance for nothing.
Changing oil, spark plugs and filters all fall into the preventative maintenance category, things which we do to both keep our engines running properly and prevent significant problems from occurring. Changing the water pump’s impeller is often included among these tasks and for those with inboard diesel engines, or those with outboards on boats which are used seasonally or are kept on trailers, it’s probably easy enough to do. Unfortunately, in order to access the impeller on our Yamahas, the engines must be pulled out of the well and the lower units must be removed, tasks which are difficult enough to make this something that does not get done as frequently as it should. At least by us that is.
Note: Our friend Drew wrote on his blog how he pulled the lower unit while in the water! Crazy? I think so!
For those who are not up on the role of the impeller, and I would certainly have included myself in that group not all that long ago, the impeller is part of the raw water pump which draws water into the engine to cool it. Without it functioning properly, the engine will overheat, something that ours was definitely doing. On a properly running outboard you can typically see a “pee stream” of water exiting the engine when it is operating. This tell tale does not guarantee that the water pump is all OK nor does a lack of it mean that the water pump is not functioning. It is a good indicator though and we try to always ensure that we see this stream when the engines are first started.
Although we did observe the stream prior to our experiencing our engine issues, no water was flowing when we began troubleshooting it. Additionally, the engine was running very hot, another symptom of a cooling problem. Always checking the easy things first, we got in the water to remove the water intake plate to see if it was clogged. It was there that we saw little bits of black rubber, a sure bet that the impeller was toast. Given that I had never changed it, that was not all that surprising for me.
Like all maintenance jobs that we do for the first time, we entered into it with a tiny bit of apprehension. We had read about the difficulties of separating the lower unit from the main part of the engine and were not eager to have that kind of fight. Fortunately for us, pulling the engine, a job which we had done before, and removing the lower unit actually went quite well. In truth, we were feeling quite good about ourselves when we removed the water pump housing and saw that our assumption was correct, the impeller had indeed been trashed. As luck would have it, our repairs went downhill after that though.
All ready to raise the engine. We re-tasked the block and tackle from our dinghy davits for this job.
Our outboard engine “work bench.”
The lower unit removed. Things went downhill after this.
Do you think the impeller needs to replaced?!?!
All documents that I have read state that if you’re going to go to this much trouble, you might as well replace all of the serviceable parts in the water pump instead of just the impeller. No problem for us, we have a water pump service kit for just that purpose. The stumbling block to completing this though was removing a pesky little piece of metal called a woodruff key. This half-moon shaped disk fits into a slot in the shaft and when mated to a groove on the impeller, forces it to turn with the drive shaft. Unfortunately, it needed to be removed to access the other parts of the water pump. Do you think it would come out? Not even maybe. We tried pulling on it with various types of pliers, dousing it with penetrating lubricants, tapping it every which way and even heating it for a bit with a lighter. None of those solutions worked. In cases like this, we always consult the Oracle to see if we’re missing something but without decent internet on the boat, we couldn’t even do that.
Problem two reared its ugly head when we turned the water pump’s plastic housing over to inspect it. It was then that we saw how the remnants from the impeller had all melted inside of it. I believe the housing itself was actually melted too but even if it wasn’t completely trashed at that point, it is now. I messed it up trying to remove the metal insert. 🙁
Have you had enough bad news? Well, here’s the good news. Following a trip to shore to get internet, Rebecca found a source of water pump repair tips that included a method for removing the woodruff key using a chisel. Did it work? I am happy to report, yes. The second bit of good news is that the water pump housing that we destroyed is not a super-expensive part. They sell for only $30.00 on Boats.net and I have since ordered two, along with another water pump service kit for the other engine. These parts are being shipped to our daughter’s and we’ll pick them up when we’re in California in 2 weeks. Remembering what I wrote yesterday about St. Martin being a great place for repairs, there is still a chance that I might find the part I need to purchase here and assuming that I can, and it’s not stupid expensive, we’ll pick one up. Until such time that we do obtain that piece, our starboard engine is going to be living on our cockpit floor. We’d much prefer to get it back in the water though.
The pesky woodruff key!
The water pump housing. Yeah, this doesn’t look good.
We definitely deserved a drink after all that. Frozen Mojito at Barnacles… MMMM!