Mainship 400 Twin Engine - Change impeller on Port Engine

[Butch Hammel]

On my 2007 Mainship 400 the impeller on the port engine is almost impossible to get to. Anyone figured out the best approach or any special tools to get to it? Thanks

 

[DavidM]

Do you have a Cat, a Yanmar or a Cummins engine?

The Cummins 6BTA usually requires lifting the engine off of the engine mount a little to get clearance to remove the pump so you can replace the impeller.

For the Yanmar 6LY you need to remove the pump also to more easily replace the impeller, but I don't think you will have an engine mount interference.

Don't know about the Cat.

David

 

[Butch Hammel]

I have Yanmar 4LHA 240hp engines.

 

[Tonic1]

On my Pilot 34 with twin 4LHA, I removed the pump as there is not room to replace the impeller while the pump is installed. I believe I had to remove the alternator bracket to get better access. Not sure of the engine room layout on the 400, but Ton the Pilot, the starboard engine has the same issues, just a little to get in position to work on it.

 

[Comodave]

I have one water pump that I cannot even see. I had a horrible time changing the impeller. The marina where the boat was stored when I bought it said the mechanics drew straws when it needed an impeller change and the looser had to do it. I found impellertool.com and got one that fits my water pump. Wonderful little tool. It allows you to slide the impeller into the tool and then slide the tool into the water pump. Then hold the impeller and pull the tool out. I also bought a Jabsco impeller puller. It comes with a T handle that you tighten up and pull the impeller out. The T handle would not turn on my engine due to a pipe being in the way. I had to get some metric all-thread and put double nuts on it to turn the all-thread. Now I can change the impeller in about 20 minutes, much better.

 

[Dougcole]

The only way to do it, unfortunately, is to pull the pump.


Getting it off is pretty easy, once you get the hang of it, but getting it back on can sometimes be a jagged little pill to swallow. I started a thread about this some months ago that may be of some help, I'll link to it in a below.


The thing you want to avoid is spinning the pump shaft when you remove/replace the impeller. If you do, it is hard to get the pump lined back up with the studs that hold it in place. The best thing to do is to carefully mark the shaft and housing before you pull the impeller.


Leave the inlet hose attached to the pump, no need to take it off.



The port side impeller change is the hardest regular maintenance job on these engines, the stb side is easy.


Here's the post: https://www.trawlerforum.com/forums/s6/tips-raw-water-pump-install-48377.html

 

[Butch Hammel]

I want to thank all of you for the guidance and good ideas. And thanks to dougcole for the link to a past thread on this subject. Guess all I got to do now is just go do it! Thanks Butch