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1. Neglected Services - part 1
- Replacing the impeller of the engine's sea water pump

[Click images for larger versions]
Left: recently replaced impeller; almost all
vanes are gone. Right: the new impeller
This is how they looked the previous time.
On the photo to the right you can see ..
Rubber parts from the damaged impeller.
They were found in the heat exchanger

If there is one particular service issue that tends to be neglected aboard Scorpio, it is the impeller on our Perkins engine. Because this impeller is so painful to access, I sometimes change it too seldom. On the two photos above (left and centre) you can see what happens to the rubber impeller over time. On the third photo (right) we have the vanes that have been torn off the impeller. They were found in the heat exchanger (down stream of the sea-water cooling circuit). The front end of the heat exchanger is even more painful to open for service, so if things have gone this far I'm being cruelly punished for my neglect.

The photos below are from Perkins's Workshop Manual. They are absolutely ridiculous. There is simply not enough room to put in a hand into that space, let alone one that could work the pliers. The photos have probably been shot with the engine on display on a convenient level and with space to walk around it. It is showing a right hand, which indicates that the guy is standing on the port side of the engine. Compare to the photo on the next row below (#1 left).

Photos left and right:

Let your mouse hover over a photo for details of hand and water flow.

All photos:

Click on a photo for a larger version.

The two photos in the centre below (## 2-3) are from the real world. They show the area from above (looking in the direction of the upper yellow arrow on image #1). The part with 3 electrical connections (image #2) is the oil pressure sensor, which has to be taken out of the way. Behind it you can see the cover of the water pump. In image #3 the sensor and the pump cover have been removed, but it is not possible to get a hand in here all the way down to the pump. The red wire is the transmission operating cable and metal-color rod closer to the camera is the engine-stop (connected to the fuel pump). Image #4 shows the area without water hoses, pipes, wires, fuel filter housing and other peripherals etc (compare with image #1). It was taken when we completely rebuilt the engine in 2007.

Picture in the work-shop manual.
Water pump, sea-water circuit and access-ways highlited by me.

1. Real life pictured in the 2 photos in the middle. Far right the area during the rebuilding 2007. 2. Looking down (upper yellow arrow) Oil pressure sensor is in the way. 3. Pressure sensor and impeller cover out. Impeller visible now. 4. View when we rebuilt the engine. No hoses and pipes in yet.

Scorpio has a larger engine room than many sailing vessels of the same size. There is more than a metre space above the engine, which is convenient. I can even sit on it when working on electrical installations (the back of the main panel is accessed from the engine room), the autopilot etc. Problem is, there is very limited space around the engine. Trying to access the port side (where the water pump is located) I have to lie on top of the engine, head facing forward (to the left on image #1). In this position I can reach the water pump with SOME of the fingers on my LEFT hand, but I can not see the area anymore (the hand is blocking my view. Getting out the knobs holding the cover is relatively easy even for a blind, but getting them back is extremely difficult. I manage to do it with the tool shown in image #3 (close-up in image #6).

5. My left hand after an impeller-change. The right one didn't look any better.
6. The tool I used to put back the knobs holding the pump corer. It is 70 cm long. 7. Some tools have to be modyfied. The Workshop manual is essential if one is cruising in remote places. I also recommend the Parts Book.

Painful as it is, however, the process is now much easier than it was when I purchased the boat. The impeller used to be covered with Jabsco's original cover, which has 6 screws that require the use of a screwdriver (image below, left). This would be almost impossible. Remember: restricted use of left hand only and no visual! More than 10 years ago I installed the Speedseal, a very clever cover kit. There are only 4 bolts, or knobs, which can be turned by hand and only 2 of them have to be taken out completely. When opening the cover, you leave the lower two bolts in place so that when you again return the cover you can just drop it in place, guided by two slits (se image below, right). The cover will stay in place by gravity until you get the two upper bolts back in place. Genius!

But if I have to take out all bolts for some reason, like last time, I still have to use a tool to get the lower two bolts in place (see image #6 for a close-up and #3 for a view in action).

Original cover requires screwdriver
Speedseal's bolts turn by hand
See speedseal.com for more info
Speedseal has slots for guidance
Click image for larger demo

The hardest part today is getting the old impeller out. I haven't found an easy way to do this yet. There is no space for even a small puller like the one pictured below. I'm presently in the process of designing my own tool, and will upload an image of it when/if it is ready. Today the whole process of changing the impeller takes me around three hours provided that the boat is not rolling, and it cannot be done when the engine is hot.


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