I got the impeller out by gingerly persuading it with a very small screw driver "the size that is used to adjust carb settings on a small engine" and lightly prying off of the pump housing. I could only pry on about 90 degrees of the housing as that is all that is reachable. I did have to completely remove the alternator, and discovered that when the top arm bracket bolt that secures the bracket to the motor is removed, will drip coolant from the engine head. A slow drip, but a drip none the less, so the alternator bracket had to be reinstalled, adding another restriction to an already limited access. The alternator was removed and disconnected from all wiring harnesses. It was such a delightful experience, that I wish I could convey my deep appreciaition to the Yanmar engineering staff on a fine job well done. My little sister could have done as good.
Next, replace the impeller. Arrg. I greased up the splines on the drive shaft of the impeller pump and the inside of the impeller housing by feeling my way through it. No big deal there. Next, I needed to orientate the impeller vanes in the correct direction and at the same time line up the splines between the impeller drive shaft and the internal splines on the impeller, without being able to see much at all is this is facing the rear of the engine. Arrg. I ended up using a plastic wire tie to secure the vanes in the correct orientation compressing them and making the OD of the impeller quite a bit smaller. Then by usuing the tail of the plastic wire tie as a handle I was able to hold it in one hand whilst rotating the impeller with the other hand to try and line up the splines, all the while using my chin as a balance point to rest the upper part of my body on. Arrg. It sucked in, the bastard actually went in part way!Then I cut the wire tie off and pushed the impeller the rest of the way into the pump housing. I am waiting on the speedseal to arrive, which I thought was a good suggestion, which I had already considered early on, but blinked on the idea.
The 3JH2 already uses an o-ring for the impeller cover seal. To remove the impeller pump housing I would have to remove the front port engine mount bracket. Arrg. I really did not want to leverage off of the impeller housing but as I studied the limitied access environment, it became increasingly clear that to use an impeller puller would necessitate removing the engine starter motor. Arrg. This task is not meant to be accomplished in a seaway, nor is it a fast fix like some impeller changes are.
The job is finally completed awaiting it's test when the boat is launched this spring. The speed seal install went well of course. The alternator reinstall went ok, but like this entire task it sure was close quarters. This Yanmar is beginning to remind me of a Triumph 500cc trophy motorbike that was previously owned. Wouldn't you think that engineering could have gleaned something after 30 years?
Last edited by RickBowman; 03-12-2007 at 08:58 PM.