Changing impeller and belts on 25SC with 4BY engine

[SmallChange]

Has anyone had to inspect or change the raw water impeller or water pump belt on a 25 SC with the 4BY2 engine? If so can you give me any advice on how best to get access and perform the task? It looks like one would need very long thin arms and the ability to work by feel or using a mirror. I'm hoping that it is not as awkward as it looks.
I haven't yet reached the point when I need to do this but I would like to figure it out and be prepared with the proper tools before the need actually arises. Any advice would be appreciated.

 

[ttlmac]

I'm glad you asked this question and hope someone responds. I have the same engine in the R25 "classic". I don't think there's any tension adjuster on the pump belt; I was told that the belt would need to be cut to in order to remove the housing and access the impeller. I'm new to all this, so hope some of the more experienced people can answer your question.

Tom
Indian Summer

 

[Stella Maris]

Lyman and I attempted to change an impeller on a R-25 110 Yanmar while in Desolation Sound. We did not have to cut the belt as Lyman worked it off with a screw driver. You will need an impeller puller to get the old impeller out though. That is why we "attempted" to change it. We did not have a puller and could not get the old one out. Lyman was able to determine though that the old one was still in decent shape.

You will need to be able to stand on your head (Lymans job) for about 45 minutes though to do this job. You will also need a skinny assistant (my job) to hand you the tools and screws as you need them.

It can be done, it is just not an easy job.

 

[yuukis]

Unfortunately, I have had the unenviable job of replacing the impeller on my R27, which will be the same as the 25SC. Difficult but doable. First of all, I am skinny. You will need to remove the hatch at the step into the cabin entirely to get access. You will have to remove the vertical panel that is on the port side of the boat just next to the step and then remove the panel that you are looking at through the hatch opening that you just removed to expose the front part of the engine. Now, you can squirm your body into that opening and you can see the raw water pump and belt that you need to remove over on the starboard side of the engine. You will need a 3/4 inch socket to rotate the main drive pulley on the port side of the engine. Not easy because you are working against the compression of the engine and you can only move the belt and inch or so at a time. While rotating the pulley with your right hand, you will have to work the belt off the impeller pulley with your left hand a bit at a time. This is a ribbed belt and comes off with sweat and a few choice expletives. The pulley housing is attached with 4 6mm allan bolts and I have a socket wrench with an allan set that works well. You will probably need a bout a 2-3" inch extension to get in. The housing comes off easily and the impeller can be pulled out with needle nose pliers . For me, the hardest part was getting the new impeller in. It is very awkward and you have very little maneuvering room. I was unable to do it and Andrew saved me by coming by and putting all back together in short order. He said it would be much easier next time. I have been told that if you put the new impeller in hot water, the fins are easier to compress and it goes in with less problem. Once you get this all together, make sure the belt is completely on. It won't center itself because of the ribs and grooves on the pulley.
Good luck. I hope it will be a couple of years before I have to change the impeller again.
Charlie
P.S. Make sure you have a magnetic wand to retrieve the allan bolts that you almost surely will drop into the bilge.

 

[SmallChange]

Thanks for the responses and advice. It still sounds like an awkward and perhaps very difficult and frustrating job. Has anyone considered alterations to make the step into the cabin removable? It looks like this would give much better access to the front of the engine without having to fit through such a small opening. Does anyone think cutting around the step to remove it would have any negative structural implications?
Any opinions and/or advice will be greatly appreciated.