Originally Posted by Seastream
Addendum: Once I've resolved this situation, I've considered replacing the two 'machine screws' closest to the engine block with a smaller diameter bolt/nut/washer assembly, with the bolthead at the front of the engine, to facilitate future removal
At the beginning of the season I thought I would check the raw water cooling
rate on my VP D2-40 engines very carefully - after 6 seasons use I have had no problems so far. Starboard engine 12litres/min, the port 5 litres/min. Spend a couple of days checking everything else. It had to be either the sail drive intake or the pump. Decided to try the pump first as I thought it would be easier to swap the pumps around then re-plumbing the raw water
supply. In trying to do this I found that both water
pumps needed the seals
changing. Now this seems a common problem on these D2/D1 engines. Why do these pump seals
last less than 800 hours, thats only 20000 miles in a car. Water
pumps on cars last much longer.
Yes removing the water pump seems simple enough in theory until you try. On the D2-40 engine, VP have just added a "box" which contains the water pump "gears into the engine drive". The 4 bolts that hold the pump onto the box are threaded into welded on external nuts. As the bolt is 10mm longer some of the bolt's thread is exposed. I removed the port pump no problem. However the starboard pump bolts would not undo. This was because they were totally corroded. To cut a long story short I managed to removed 2 okay. The third bolt sheared. I was careful using a 1/4 socket drive and I don't believe I could have removed it. I then spend several hours cutting the welded nut off in a very confined space using every tool imaginable. Once done I have replaced it with a SS bolt and nyloc nut. After that I gave up trying to remove the pump. The fourth bolt I have left to the end of the season.
TIP - grease the ends of all these bolts to keep the corrision at bay.
Fortunately the problem was the sail drive water supply. I rigged a raw water feed from the port rear head
intake and now I get 12 lites/min.
As the boat was in the water I couldn't check the stop cock. Last year I helped a fellow cruiser remove the VP saildrive
in order to change the large main water rubber seal. In doing so the saildrive
is split into two and we found a large marine
growth, bigger than the raw water supply passages beginning to block the water supply. So it is important to visibly check the water passages in the saildrive whilst it is apart. This issue has not been mentioned in any of the articles I have read which explain how to change this seal.