My Outboard Motor

I was encouraged to put this story up on the website during a lunch break discussion about dodgy hardware. Mostly it was PCs but the outboard deserves a little mention of its own.

The engine

It is an Evinrude 2.3HP 2 stroke. When we bought it in 1997, it had a faded stop button and part of the catch holding the cowl on was broken. The price was reasonable. This evidence of extreme age was ignored as it was new in all other respects.
For some unaccountable reason we bought it on a trip to Sandwich in Kent, as a part of a visit to my parents.
It worked well with the Avon Redcrest bought for 200 at a boat jumble, especially after I made some rigid floorboards from marine ply.

Its early years

It looked quite reasonable until one day on a summer holiday cruise, when it was attached to the Redcrest, as a part of a gaggle of  tenders jostling against a quay wall at Fowey. It lost one of its catches and the transfers on one side on the granite. Shock cord to the rescue. It has worked well ever since and has proven very useful for immediate access to fiddle with the idle screw on the carburettor.

Its Middle Age

Each time it came out and was used it got harder to start. It happened gradually and we just got used to the starting position. Set the throttle to start position, the choke nearly closed. Set the steering friction lock to tight .
One hand holds on to a fixed object, the quay or a boat. The other hand makes repeated violent movements pulling the starter cord until the engine fires.  The throttle
has then to be fiddled with as the engine changes as it warms up. Most of the time the throttle is set too high for easy control at low speed. Loosen friction lock to allow steering.
Once running OK it was easy to start  so I would not remember the problems later .
Taking out the spark plug and cleaning it often improved the problem. There was a suspicion that the wetness was water.
So I changed the cylinder head gasket , cleaning out salt deposits and the problem did not really change. I did this several times. I never took it to an outboard dealer but DIY fixed it all of the time.

2003 : final diagnosis

On one occasion after a couple of months of  non use the spark plug gap was rusty. Fairly conclusively it was water in the cylinder ....
A new fault emerged. Once the engine could be persuaded to start and run with a clean plug it would run up to a high speed and then die completely. After some more starting fiddling it would run badly ..

Some work with the idle control and the engine could be persuaded to fire once every three or so revolutions firing just before it stopped. In this way we staggered from Beaulieu quay outside the Abbey down to Buckler's Hard in April. And again in Salcombe in July, where it could just beat the tide. I think I stripped down the engine 4 or 5 times to see if there was anything visible. Each time it would run for about 2 minutes and then die again.  I suspected the ignition coil and tried to find someone in Salcombe who would look at the engine. Nobody could.
Instead I bought a gasket and a new spark plug from an outboard dealer where the spares department person's brain was fried by the high temperatures during the summer heatwave and took several tries with a calculator to add up the bill.

So when we got back, I went to talk to a local outboard motor dealer who handled OMC products.

He suggested the problem with the water in the cylinder after replacing the gasket was a warped cylinder head. This turned out to be correct. About 0.5mm out of flat. I also discovered that the bolts holding on the cylinder head shear at exactly 23 foot pounds torque (which is pretty brutal) and that actually the correct torque was about 7 foot pounds.... Had I warped the alloy head by over torqueing or overheating , or was it bent anyway ?

Head Skimming

So off the head went for skimming and was duly lost for a couple of weeks by the company with the skimming machine, not the outboard dealer.

It came back and was fitted along with a Mercury head gasket which has a kind of sealant on it unlike the Evinrude version.
The engine blocks are the same so the gasket is an exact fit. The engine then started and ran up to higher speeds in the tank before dying again.

I also cleaned out as many waterways around the engine as possible removing the power head from the leg, and finding some salty deposits.


I eventually rigged up firstly a timing  strobe from my ancient petrol car days (about 10 years ago) along with a car battery and discovered that when the engine was misfiring there was no spark at all. I then connected a mains inverter to the battery and an oscilloscope and monitored the voltage on the kill switch which is across the ignition coil. I noticed that when the engine fired , the primary voltage was always lower than a certain amount. Once this level was exceeded the voltage would collapse randomly on each firing cycle until the dropped and hence the magneto output voltage dropped below that magic voltage again .

Outboard starter Repetitive Strain Injury

It is often forgotten that other things can cause RSI than PC keyboards. Boy did I find out! With all the pulling on the starter, I landed a severe case but it faded over a couple of weeks of stopping using the arm for anything like typing on a PC, but instead adopting a 'thinker' pose propping up my head with it on the keyboard wrist rest.

Back to the outboard

Further discussion with the outboard shop suggested that it was not the coil that was at fault but the condenser or capacitor. He seemed surprised that the engine did not have a CDI unit given the purchase date, as it should have in the late 90s. I have a horrible feeling it is 10 years older. ....

So  I got the flywheel off to get at the ignition system using a 17mm socket which just happened to be the size missing from my socket set. Quick trip up to Halfords for a new one.
I took the capacitor off and up to the dealer and he did not have one in stock . He could not find it in the spares catalogue and so I left the old one with him to match up for a replacement.

After a couple of weeks he said he had it in , so I went to collect it. However it had by then been lost somewhere in the spares store at the dealer. I am still waiting about 4 months or so since starting the repair on the engine.... I marked the dodgy one with an X scratched on the end of  it.
So if you bought a spare condensor for an older Evinrude 2.3 and it has an X scratched  on the end then your engine will run for long enough to check out but will die after about 2 minutes of hard running.

In the mean time I decided that one of the mains filter  capacitors (400 volt 1uF) found inside PC power supplies would do the job. So I soldered some long flying leads on the capacitor and covered it in hot melt glue. I then wired it in place of the condensor and reassembled the engine setting the contact breaker gap by eye to open about when a marker on the flywheel aligns with a mystical marker on the engine body. I dont have a service manual.

The outboard has since run for several minutes flat out in the tank, with an old Morris Marina spark plug . This is so long it nearly gets hit by the piston...
Problem was I had lazily reached in with the plug spanner and crunched the correct spark plug insulator with a quick turn of the spanner.
I have since replaced the plug with the right one.

26 thousandths of an inch gap at full opening is the correct setting .for the contact breaker points. When I get the new condenser back I will reset the gap.

My other Outboard

In the meantime I was given a somewhat rusty Seagull Century  longshaft. This had been last seen running 10 years ago and all the fuel had evaporated leaving an oily brown varnish all over it. Filled it with some fuel, tickled the carburettor and pulled the starter. It started immediately and ran well in the tank. I think I will spend some time cleaning off the rust and making it more presentable as an alternative - I also could use it on a bracket on Forethought the GK24, to give that period look and sound if ever the Yanmar fails. Most likely it will be used to push the Pacer dinghy around the river.

Dead Again June 2004

I test ran the Evinrude engine in the tank trying to adjust the points to get the timing right and eventually it ran up something like it should have. Then it stopped. It would not start again at all.
When I dismantled the engine enough to get at the flywheel  I could get a spark but a weak one. Then I realised that the replacement capacitor was neither short nor open circuit but lossy. I hate it.

So I went off and bought a Tohatsu 3.5, with an instruction book, a warranty, a dinky set of tools a spare plug and split pin and shear pin,  more power and a clutch. And it goes when you want it to.
Now I have an outboard I can trust with CDI ignition system, and which doesnt send you in circles when you start it.
The Evinrude joins my long list of not-working but recoverable equipment littering the garage.

Siezed Early 2006

I turned over the engine only it wouldnt. After a lot of wobbling the flywheel in a forceful manner the engine turned over again. I tried to start it and I was greeted with a 'sneeze' sound when it fired. So I put it away again.

Back again September 2006

I left my Tohatsu on a dinghy on a mooring out in the river for 6 hours one evening and somebody nicked it. So its back to the old rubbish.

Seagull running

By this time the Seagull had a lot of rust inside the fuel tank so a lot of stainless steel bolts were thrown in and the whole thing rattled around until the rust (and bolts) stopped coming out. Then rinsed out with white spirit , the outside of the tank and engine block  tastefully Hammerite'd and the engine still runs.  Loads of white smoke. I may well be seeing in the end of retail twostrokes with a 29 year old one running on 10:1 ... Datecode says May 1977.

I made a video of  it running, and uploaded it to YouTube . As a result, Ian from British Seagull Parts.com got in touch.

Back to Evinrude

The Evinrude was stripped down further and the following was found.
As far as I can tell the bearings still run fairly well so I am going to soak the whole lot in white spirit and re-oil before reassembly with new gaskets and piston ring. Even if  it only lasts a couple of years it gives me more of a chance to wait for the next generatiion

Tohatsu 3.5

I have replaced the Seagull with a Tohatsu 3.5 and this has worked well until I dropped it into the river while it was running. It stopped and I quickly yanked it out of the water by the lanyard which I alway use. I assumed that I had killed it  , as I was on the way to Hamble Point for a lift out for Forethought I didnt have time to mess about with it . So I left it back on the back of the dinghy and rowed out. Once I arrived at Forethought, I realised there was still time to look at the outboard. A few tentative pulls on the cord and I could feel some back pressure from water in the cylinder but then I took out the plug and pulled. No more water in the cylinder, dry off spark plug and replaced it. Much to my surprise it worked and ran normally. So I took Forethought up to Hamble Point and was glad of the outboard on the way back against the tide.

I looked inside the cowling and could see no trace of salt . It didnt look like seawater had ever been inside the cowling. As the engine still ran well under test, I left it as it was.

A month or so later and the outboard wouldnt start, with fuel dripping out of the air intake. On stripping down I found salt/corrosion in the carburettor float bowl - jamming the throttle full open and stopping the fuel feed valve from closing. I cleaned the salt off the needle valve and the bowl. Some time soon I probably should split the crank case to see if there is still water in there.

Mike James