Water Pump Impeller Replacement on Mercury Outboard

Mark Corke has just recently posted about an outboard water pump service. It is reproduced here on this blog, but I encourage you to go over to his blog site to read the whole story. Mark also has excellent blogs on other boating projects and topics of interest to boaters. Well worth a click to read it at the source.

Read it at Mark's site here.

After Mark gives an introduction to the project at his blog site, the project is outlined below.

The engine that we serviced was a 1996 115 hp Mercury hung on the back of a aluminum Starcraft of a similar vintage and the pictures refer to that but all outboards are very similar and although the pictures may not look exactly like what you have the sequence will be the same.

 I took the pictures as Adam Conte at Portside Marine in Danvers, MA serviced the pump. Working thoroughly and methodically he did the whole project in less than an hour so a competent owner should be able to do the job from start to finish in under two hours.

 Here's how to do it.

The first step is to drain the oil from the gearbox. Unscrew the drain plug with a large screwdriver and the oil will start to run out. Make sure that you place a suitable pan under the motor to catch all the old oil. Unscrew the upper oil level plug too which allows air into the gearbox and ensures that all the oil is evacuated. There are small washers under each screw head which often get stuck in the threads, if they do not come off with the screw you may have to pick them out with a small screwdriver or other tool. Let the oil drain as you move onto the next step.

Loosen and remove the nuts that hold the lower unit in place, almost all outboards have four nuts holding this in place. A socket will not fit so use a ring wrench to give good purchase on the nuts which will almost certainly be stiff to undo.

 The lower unit should now theoretically be free but in practice it almost invariably sticks and will need a few taps with a soft mallet. Do not hit the flange cavitation plates at the sides or they are sure to break, a few taps on the after end of the gearbox unit as shown here are acceptable however.

 Once a crack opens up the battle is won and you can insert a broad screwdriver and carefully pry it apart being very careful not to damage the castings of the mating surfaces.

 Lift the unit clear and place it on a suitable bench or jig designed for holding it. They service outboards everyday at Portside marine so had a proper jig on hand which is ideal but you may have to prop it upright in the corner of the garage, it works but is just not as convenient and you will be working at floor level.

With the unit clear of the top half of the outboard leg we can get to work on the pump proper. The first thing to do is to slide off the seal which sits atop the pump housing. 

Unscrew the bolts that hold the pump housing in place. We needed an impact wrench as this pump had not been serviced for some time but a ring wrench will work in most cases. Avoid using an open ended wrench, if you round over the bolt heads you will have a bad day for sure.

Separate the housing and slide it up the shaft. You can see in this picture that the bottom plate is coming off with it. We need to remove this plate also so if it stays stuck in place you may need to pry it up very carefully.

All in all the pump was in pretty good shape, all the vanes on the impeller are intact. Note the old impeller on the right next to the new one on the left. The vanes should be straight, they develop a set to them after they have been in the pump for several months.

 Before reinstalling the pump clean up all the mating surfaces to ensure that there will be no leaks. A sharp razor blade can be used to scrape off the larger bits of old gasket and sealant, then some fine emery paper will get rid of the remainder. Wipe down with some clean rags when you are finished. Everything should be clean and bright.

Clean out the interior of the pump housing checking to make sure that there are no score marks or gouges, if there are water may leak past the vanes of the impeller and the pump will not work as efficiently as it should. If there is any doubt as to the condition of the housing then it should be replaced.

In addition to the impeller all the parts that are required for a routine service; gaskets, O rings and seals are included in the kit.

After cleaning up everything reassembly can start. Smear on a little gasket cement. Adam swears by Permatex Form a Gasket sealant liquid but any other proprietary brand should be fine.

Lower the gasket into position making sure all the holes line up. The gasket is asymmetrical so if something looks wrong you may have it upside down.  Next install the new bottom plate (shown) that comes in the pump kit, we used a little more gasket cement before dropping this on.

Install the smaller gasket which seals the joint between the top and bottom sections of the pump housing. This gasket has a neoprene bead built in so no cement is required or should be used.

Install the new key which sits in the flat on the shaft.

Then slide down the new impeller making sure that the key-way in the hub lines up with the key previously fitted.

A little glycerin or dish washing liquid makes getting the pump cover on that little bit easier and provides some lubrication for the second or two until the water gets into the pump and lubricates the vanes. Do no use oil or silicone which can attack the composition of the impeller and lead to premature failure.

Slide the housing down and ease it over the vanes as you twist the shaft in a clockwise direction with the other hand. This bends the blades and allows the body of the pump to sit fully down onto the base plate gasket.

Reinstall the bolts and tighten them till they are just snug.

Slide the new seal down over the shaft until it just rests against the pump housing.

A setting tool is included in the kit and this is pushed down on top of the seal and does double duty of spreading it out and ensuring that it is not compressed too much. With the seal thus set the compression tool is then removed.

Smear a little engine spline coupling grease onto the top of the drive shaft.

Then a little more on the gear shift coupler which should still be on the gear shift shaft inside the leg, it is a fairly loose push fit so it may have fallen off onto the floor if it is not where it ought to be.

Refill the gearbox with the correct oil. Note that contrary to what you might expect the oil is forced in from the bottom until it comes out of the upper level hole, then both screw plugs can be replaced with a new washer under each. Portside marine service lots of engine so that have a big tub of oil but the average DIY boater is more like to use the oil that comes in squeezable quart bottles but the technique is exactly the same.

Reinstall the lower unit onto the leg, it helps a great deal to have a helper rotate the engine by hand a little to get the splines to mesh. Then replace the nuts and washers that hold the two parts together, there are torque settings for these but Adam does them up so they are just snug. As long as you don't swing on the wrench it is difficult to over tighten these. 

With everything back together the job is complete. We ran the engine in a barrel to make sure all was well. You can use muffs on the water pick up but the pressure of the hose tends to force the water into the engine, running it in a barrel ensures that the suck from the pump is correct. Note that there should be a healthy spout of water coming out from the telltale in the engine housing.

Homemade Teak Cockpit Table

Mark Corke has once again turned out a great boat project;  a beautiful looking cockpit table.

I've tried a cockpit table in my cockpit, and ended up using hinges and support legs. I eventually removed it. Mark has a unique way of doing this and the pictures on his blog site say it all. Hop on over to his blog site to check the whole project out

He says this about the table.

 " I think that the pictures are fairly self explanatory but what I like about this table / cup holder is it's simplicity; no fancy hardware and nothing to break. As you will see it is all made from teak and teak plywood and consists of a drinks holder securely clamped to the crash bar ahead of the compass binnacle. When out cruising this offers a great place to hold mugs and cans without fear of spillage and yet within easy reach of the helmsman and crew in the cockpit. But what really sets it apart is when you get into port and you need to set up the table for alfresco dining. The table is simply lifted off it's stainless hooks and pulled away from it's clips keeping it neatly in position and slid into the horizontal, no metalwork, flaps, hinges or other impediments to adjust or break off for that matter. "

Cruzpro

Shortly after writing about my Paddle Wheel Dilemma, Mark Corke also wrote about the Cruzpro (also mentioned in my blog) and offered up some pro's and con's. Go over to Mark's blog and have a read. He is going to buy one and install it. Keep an eye on his blog site for updates and reports of this interesting device.

Finished Teak Grate

Marke Corke has finished his teak grate and I wrote about his cutting jig here.

Hop on over to Marke Corke's site to read about his write up of this wonderful wood working project. Plenty of details are there, along with lots of photo's.

Teak Grate Cutting Jig

Mark Corke has a teak grate project in hand and shows us how to get perfectly spaced rebates on his teak project. Mark explains first of all, how he came to be making a teak grate. You can read his initial blog here, but essentially he says...." The alterations also meant that I had to install a couple of water tight hatches in the cockpit sole and although they seem robust enough I am a little nervous about walking on them. I don't think that they would break but somehow the cockpit just does not look finished. So I have spent a long time agonizing over what I should do and I have decided to go down the route of the classic teak grating. .....".

Mark, in part two goes on to explain.....

As you can see I made a jig from a couple of sections of scrap three quarters inch plywood into which is cut a slot exactly the same width as the notch that I required in the grating

Off set to one side is another section of wood glued and pinned in position which slots onto the groove already cut and thus giving the current spacing.

To prevent break out, it is essential to back up the cut on both sides. One side is supported by a back fence screwed and glued to the template and the front is supported by another scrap of wood which is simply held in place as the strip is cut. Finger pressure is sufficient but obviously keep your hands away from the cutter. In this shot, I am holding the bearing cutter to illustrate how the whole system works. Of course normally the cutter would be held in an inverted router on a table.
Use a sharp carbide tipped cutter; teak is very abrasive and will dull a HSS cutter in no time at all.

Clean cuts on Plywood

Mark Corke has shown us a wonderful tip for cutting ply. Go on over to his web site to get the full blurb.

Mark says.....  The picture shows some cuts that I made in half inch thick marine ply and as you can see they are perfect straight from the saw. The blades that I use for this type of cut is the Bosch 101AO, which have needle teeth not too dissimilar to those found on Japanese pull saws. With the pendulum action turned off they really are the nuts with almost no tear out even when cutting against the grain on the face laminate. A quick trawl of the internet shows these blades can be had for around $8 for a pack of five which considering the little cleaning up you have to do once you have cut out the component is money well spent.

Stitch and Glue Pram Dingy. A Weekend Project

Here is a project by Mark Corke, which would only take a couple of weekends to complete. It follows the traditional stitch and glue method  and below is a small extract of his project. The complete article  can be read at  his web site here

snip...

"A kit boat is good introduction to boat building, as little preparatory work is needed before construction commences. You will need some space and typically this will be the family garage but because the boat takes shape so quickly the car will not have to stay outside for more than few days.

The boat is built using what is often called the stitch and glue method, pioneered successfully many years ago by Barry Bucknell and Jack Holt in the mirror dinghy. Now however rather then using polyester resin and glass tape epoxy resin has taken over and is used both as glue and coating material.

 The average reader is likely to have more than enough tools and skill to successfully build this boat but I would strongly recommend building a couple of strong sturdy saw horses on which to work. Make sure that the work area floor is level because it is all too easy to build a twist into the boat. Read the through the instructions several times before you start is a piece of advice that I should have told myself in past construction projects. Reading the plans and instructions that come with any kit will make the project go that much easier.

I mostly followed the manufacturers instructions but where I deviated I did so as either time saving method of work or because experience has taught me that their might be a better way of doing it. Next issue I will be concentrating on painting and varnishing.

Building the Eastport pram took me about 40 hours of building time and this is a reasonable estimate but expect to put as much time in again on the finishing if you want a high quality job." continues.......

The whole project can be read at this link here

Heap Big Job Mate! A new cockpit floor with Beckson Hatches

 
The original sole looking aft at left

.

A big job replacing the cockpit sole with Beckson hatches  for access. Mark Corke explains how...

When I built Mallard my gaff rigged cutter I was never quite sure how to finish off the sole of the cockpit. On the one hand the cockpit needed to be water tight but on the other hand I also needed to have access for essential maintenance to the stuffing box and primary fuel filter. The other problem was that the cockpit sole was very close to the water line so rigging up the drains so that they would be self draining also became something of a headache, on a larger boat with more free-board the sole is higher and the water can run through drains and exit the boat above the waterline. This was not possible on Mallard so in the end I connected both drains to an inch and quarter sea cock in the bottom of the boat. This worked well enough but it meant that the sea cock had to remain open even when I was not on the boat and this made me nervous not least because if the clamps let go or the sea cock failed water would flood in and the boat would sink. I thought about the problem for several years not quite sure what to do. Finally I came up with the solution that you see in the following pictures, the old sole was completely removed and a now marine plywood sole installed. Two Beckson watertight hatches were fitted to allow continued access to the area under the cockpit and the drains were routed to a self contained sump pump which keeps the cockpit dry and means that the large sea cock can be dispensed with allow me to sleep easier at night.

 Of course every boat will be different and if the hatches are installed in a cored fiberglass deck then I would recommend scooping out some of the core after the cut out has been made and filling with a thicken epoxy to prevent water from migrating into the core material.

 One final point and that is to carefully think through the install before you go cutting into anything; will the hatch interfere with anything above and below decks, will it weaken the boat and do I have the necessary skill set and tools to enable me to complete the installation in professional manner.

Here's how I went about it in words and pictures.

 

Step one was to remove the old drains, which were big, mostly because they incorporate a non return ball valve to prevent water from sloshing back up into the cockpit.

 

The next step was probably the most time consuming of the whole project for me, it was certainly the messiest. Using a Fein multimaster I cut out the existing sole but left the bearers in place as I would need these later to support the new sole.

 

Once the old sole was out of the way I was able to accurately measure for the new half inch marine plywood that would make up the new section. I then cut this out with a circular saw with a fine tooth blade but I could have used a jigsaw. To allow a little room for the epoxy and also to make sure that the ply would not get jammed in I allowed an eighth of an inch clearance all the way around.

 

 

After cutting out the ply to the correct overall dimensions the cut outs for the hatches were marked and then cut out with a jig saw. Like the overall size of the play I made the cut outs and eighth oversize to allow for a little movement.

 

I then bored for the new drains which was much easier to do off the boat. I used a drill press which gave a perfect hole but a hand held drill would have been almost as good had the machine not been available.

 

I used a brass plumbing fitting from my local home store which has a screw on one end and a barb on the other which is perfect for three quarter inch inside diameter hose. With the holes drilled I had a dry run before permanently gluing them in position.

 

Mixing up some epoxy thickened with colloidal silica and wood flour to a mayonnaise consistency I used mahogany dust which gives it the brown color.

 

I then spread a goodly amount onto the screw threads and the inside of the hole and screw the fitting down into position, notice the squeeze out which is ideal. I then left the epoxy to set overnight.

 

With the epoxy set I used an 80 grit disc on the random orbit sander to sand the brass fitting which was slightly proud of the plywood flush. It is important to keep the sander moving for if the brass gets too hot it will soften the epoxy and could weaken the bond.

 

There are two things to do before the the sole can finally be permanently glued in place; drill and countersink holes for the fixing screws and coat both sides of the sole with unthickend epoxy to seal out any moisture.

 

The sole is then ready to be installed and I glued it in place with epoxy thickened to the consistency of peanut butter with colloidal silica which makes a very strong bond once set.

 

With the epoxy still wet the sole is screwed in place. In truth the epoxy is plenty up to the task without using any screws but the screws hold the sole in place whilst the epoxy sets up and don't do any harm if left in position. I used brass screws but if they were in an area that were to be subjected to a lot of sea water than I would have used bronze.

 

With the sole screwed in place I used some more thickened epoxy to fill over the top of the screws and form a fillet (pronounced fill-it) in the corner to provide a smooth transition from the cockpit side to the sole. A maxed out credit card with the corner trimmed to a large radius makes the perfect tool.

 

When the epoxy has set after a day or two the whole sole and fillets were lightly sanded and the paint applied to match the existing surrounding paint. I have found that the best paint over epoxy seems to be the Interlux Epoxy Prime Kote which is then followed up with the colored top coats.

 

With the paint dry the next and final stage of the job can start. The hatches are dropped back into position and the holes for the mounting bolts made. I used an automatic center drill to create a pilot hole. When all these have been completed I removed the hatch once more and set it aside.

 

On the underside of the hatch in hard to read writing is stamped 'use a 12 mm diameter drill'. This is to allow the hatch to move during temperature extremes. It may be tempting to simply fix the hatch in place with some suitable wood screws but it you do there is a good chance that the plastic around the mounting holes will crack as the hatch expands and contracts at different rates to the ply substrate.

 

Using the pilot holes as a guide I drilled the holes to the specified 12 mm with an auger drill.

 

The hatch is ready to be installed but before squirting on the silicone I taped some blue painters tape all around the opening where I knew it would project under the hatch flange. With the hatch dropped back in place a razor blade is run around the perimeter tracing the outline and cutting through the tape.

The hatch is once more removed and the tape on the inside of the cut is peeled off.

 

Some silicone sealant is applied around the entire perimeter.

 

The hatch is then bolted into position with 10-24 stainless steel flat head machine screws, backed up on the underside with fender washers and nuts which are also stainless.

 

Then the perimeter tape is peeled up pulling any squeeze out with it leaving a nice clean and tidy job with no need of any rags or chemical solvents.

 

The finished job all ready for another season. A teak floor grating will be installed in due course.