Engine Cooling Water Pump

I just changed mine last weekend and thought I'd add my observations.

Thanks for the really great info, it helped a lot because I wasn't sure where the water was dripping from, but I noticed the weep hole and my oil was pretty foamy.

The new pump and the wrench-grinding sounded like a hassle so I tried to find the original pump but I couldn't. So I ordered the parts above, and brought my grinder and some cheap wrenches to the marina. My original bolts were 12mm so try it out before you grind a 13mm wrench.

My bolts were really rusty (PB Blaster got them loose) so I replaced them with allen head screws (M8 x 25 I believe). I was able to get them installed with a regular allen key (L-shaped), slipping a box end wrench over it for leverage. So I avoided grinding my wrench to fit.

Now I can run the engine without mopping up after!

-Mike (Firebolt)

The cooling water pump on my engine failed just as I was about to pull the boat for the season. It wasn’t the impeller, it was the shaft/bushing.   If you look at Page 34 in the Laser 28 Owner’s Manual you will note that the water cooling pump is driven by a vertical shaft which has a gear (Item 40) in the oil sump of the engine. You should note on Page 43 that the cooling water pump which came with your engine has an internal stainless shaft inside what appears to be a bronze bushing. Over time these surfaces wear and will eventually allow water to go into the sump of the engine. When the pump fails in this manner it will continue to pump water through the cooling system so you will not know it failed unless you regularly check your oil or look at the pump when the engine is in operation. There is a hole in the side of pump housing and water will pour out through the hole, some of which will also go into the oil sump of the crank case. Since my boat was the first production boat I would strongly suggest everyone regularly check the pump or even replace it with the newer model pump which has a bearing in place of the bushing. Water in oil turns the oil a milky color and this can cause a catastrophic engine failure.

Johnson Pump (http://www.johnson-pump.com/jpmarine/marinedistributorsusa.html) is the distributor for the pump worldwide. The manufacturer that supplied the original bushing pump for the Bukh engine also makes the replacement pump with ball bearings. Apparently the older style bushing pump is also available. Here are the ball bearing pump part numbers:

Qty          Item                                           Part Number
(1)        Water Cooling Pump (ball bearing)               10-35157-3
(2)        Clamps                                           01-43238

Note also that the two Clamps identified above replace Item 51, Flange, on Page 34 since the bearing requires a housing larger in diameter than the earlier bushing design. This larger diameter also causes a clearance issue when you tighten the bolts which hold the pump to the housing beneath it.   To secure these bolts you will need to purchase a twelve point 13 mm box end wrench and grind down the outside wall so it will fit on the head of the bolts. The Clamps go on with the flat side up against the bolt head. I found it easiest to remove the impeller to align the shafts during pump installation. I also took off the Elbow for Breather Pipe (Item 5, Page 34) for easier access during installation, but I kept the nuts on the ends of the four bolts to protect the threads. Note also that your impeller, the pump cover plate, and the screws which hold it on the bushing pump are the same as on the bearing pump, so save those parts as spares. Items 53 and 54 (Page 34) from the bushing pump will fit on the bearing pump. All three items (pump and two clamps) with shipping should cost about $300 US. Considering the age of these engines and the potential consequences I believe this would be money well spent even though your original pump may not be leaking quite yet.

If you decide to replace the pump I would also suggest that you check your oil filter at the same time. To do this you will need to purchase a 17 mm open end wrench. I would also recommend that you bend the handle of the wrench about 15 degrees to provide easier access to the Locking Screw (Item 10 on Page 34). You may have to remove the Oil Pressure Switch (Item 11, Page 34) to remove the Locking Screw, but I was able to get mine off without removing it. I did have to grind down the face of my wrench to get it on inside the Oil Pressure Switch.

E-mail me if you have any question at wmabrock@gmail.com. An ounce of prevention is worth a ... and most likely save you a lot of money.

Bill