Engine Cooling Water Pump

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

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)

It plugs onto the small terminal... you may have to use pliers to get it to stay on

I think you will find that the other tab is to receive a wire for a temperature guage if you opt for one.

Seawolf: If you are running in salt water, please do one more check an that is where the cooling water re-enters the exhaust elbow. The cooling water comes from the head via a 1/2" ID hose that connects to a barbed fitting on the exhaust elbow whose ID is 1/4". If there is any rust flaking coming from either your cast iron head, or the inside of the steel cylinder cooling ports, they will jam up that 1/4" hole, the engine will overheat, and before you know what has happened the head gasket will be compromised. This will allow some water or vapor to get into the cylinder and you will have a much bigger project on your hands. A bit of vinegar won't help you. If you find any sign of rust flakes accumulating where the hose meets the small barbed fitting, then I strongly suggest that you install one of those small raw water inlet filter in that hose between the head and the outlet. The instructions will say that these fittings belong only on the intake side, but ignore that and just install the little filter such that the arrow is pointing in the correct position. This will allow the screen filter to pick up the flakes and prevent blocking the outlet. Then check that filter occasionally and empty as required.

I had this problem and it led me to rebuilding my engine. In other posts on this site you will find my explanation of how I fitting a heat exchanger to my engine an no longer run raw water through my engine and sleep much better. At the very least, if you are running in salt, you should plumb a separate pick-up on the intake side so that when you put the boat away each time after use you can run a bucket of fresh water through it. This is very easy to do.

Thanks for the heads up, no pun intended. The boat did see a trip to the bahamas about 12 years ago. After the trip the owner had the engine overhauled. That being said, the boat has been and will be in fresh water, every winter it has been winterized with antifreeze and left in the engine. The manual does state you need to drain the antifreeze but I don't think many do this.

re the thermostat housing. When I bought my boat I found the yellow wire to the alarm was cut. Why? I reconnected it but the alarm would sound and the light for temperature would light up-turns out the thermostat housing was rotated 180 degrees- for some reason, either the motor was overheating (unlikely) or the temperature probe was getting a false reading. As the alarm also warns that oil pressure is low or the membrane is leaking, I certainly felt that unplugging it was not smart.

the housing was rotated because the mechanic was stupid-no other conclusion can be drawn- the alarm was disabled because the owner was stupid-see above

tell me more about the wood fletch, what are you rerplacing?  And what is the wood you are referring to?  Can you share a link to show us?  Maybe "we" could help.....  :)bill

Regarding wood to replace, I will start with the galley and totally rebuild it to the same configuration, but replacing all plywood with glass/foam composite. Next I would do the head area, Then the long strips of ply that house the engine and holding tank.

Next I will replace the main bulkhead, but I won't use the same paneling for this as it is structural and most likely it will be a glass/foam layup of my own development which will incorporate in it the athwartship stiffening currently done by the retrofitted aluminum bar. There is nothing wrong with my current bulkhead, except that someone varnished with this orange tinted junk. Also, I think it is epoxy glued and riveted to the hull and athwartship stringer, and I would prefer a glassed-in connection. For the time and trouble of stripping all the varnish and re-finishing in situ it won't take that much more time and effort to build a new one and eliminate the wood altogether.

I have been instrumental in bringing 3 more Lasers into the Vancouver yachting area over the past few months, (there are lots of deals around), and several of those boats' joinery is in much worse shape than mine. Lots of rot, particularly in the head and on the head/nav bulkhead, so when I take mine apart to use the old ply material as a pattern to cut the new composite, I may as well cut three of everything and spread the bits around. Also, all the other boats that have come in, save one, need new floorboards, and if we have the composite, why use wood?

If you have knowledge, or a connection to a reasonable supply of either 3/8" or 1/2" composite paneling, I would love to know of it. Mostly this material is commercially produced for the construction of trailers, RV's, and for the paneling on large delivery trucks and light weight containers. It seems the marine industry is either too small or too fragmented to attract the marketing efforts of the Chinese manufacturers. However I know of a yard in Hong Kong who brings panels in by the container, and then uses what they need and sells panels to DIY people and other small yards. All my friends in Hong Kong buy from them for their projects. I suppose I could buy from them and ship from Hong Kong, but the materials will have been double-shipped if I use that source, plus I will be paying his mark-up as well.

I have considered laying up the panel myself, and I did do this back in 1978 in Hong Kong when I built the interior of my custom built 1/4 tonner, but the modern manufacturing process uses vacuum and achieves a quality finish on both sides, which I would have to go to great lengths to achieve.

Thanks for any assistance you can lend.

Frank