How do one takeout the piston from 1996 Johnson outboard 115

The piston rings, which create the sliding seal between the cylinder walls and the pistons, don't form a perfect seal. Some of the gasses from burning fuel with air makes it past the rings into the crankcase. This is normal, and the crankcase should be vented with the PCV (positive crankcase ventilation) system.

Excessive gas blowing by the rings IS a problem however. You would likely notice greater than usual oil consumption in that case.

the compression pressures are on the low side. The indications are worn rings as the pressure readings come up when the ring seal is improved with the addition of oil. The bores will be worn in a taper and if the head was to come of there would be a noticeable lip where the top ring stops in the cylinder
rings and cylinders wear equally but rings suffer from a loss of tension, and an increased ring gap that allows more compression to escape to the sump
Do you need to do something about it--
if there is an oil consumption problem( smokey) then yes
If the economy is acceptable to you then --no --not immediately
What should you consider in making a decision----
1. good engines are available from japanese spares ( imported engines with less than 30.000klms on the engine for a fair price
2. consider what is termed a "short motor" which is the block,crank, pistons ,rings,oil pump and sump all new
What you should not consider is a quickie fix--set of rings and nothing else as this will cost you more in the long run.

The oil is either leaking through your head gasket into your coolant or leaking past oil seals or piston rings, check for blue smoke whilst revving engine,and check coolant for oil contamination. check for white sludge in your oil filler cap.

head gasket or blown rings on the pistons or you ruptered a piston head at worst

If your plugs are wet with oil then you have a piston ring problem. They are not sealing and oil is flowing from the crankase around the pistons. There is a possibility that you have a bad head gasket also. Or is the question asking how is oil running down and getting on the plugs from the outside?

Your plugs are fouling out probably from excessive wear on the piston rings. Replace the plugs and check them in about 3 days to a week and see how bad they look. Clean them if necessary and reinstall them. Your engine will burn oil that slips past the rings if they are worn. Usually this will happen when the engine is cold and the rings have not expanded. The expansion is normal so what I suggest is at your next oil change use 3 quarts of the regular oil that you use and 1 quart of 20w/50. The thicker oil will help seal the rings a little better. Don't use more than a quart or 2 at the most because it will make your oil pump work harder causing premature failure.

Either your valve seals are bad or you piston rings are wore out. I would say it is the valve seals though.

If you remove thermostat water will circulate too fast and will not cool down, replace thermostat and check if your fan is turning in correct direction. Also make sure your ignition timing is ok. I found on some vehicles the waterpump seems ok but when vehicle starts heating up the impeller gets loose on the shaft. Check your brakes if they are not binding.

Whoa whoa ... You've said that the car takes 7 quarts of oil. That's 14 pints. Depending on which engine variant is fitted, engine oil capacity is either:

• 5.75 litres + 0.4 litre if the oil cooler is drained
• Turbo - 3.85 litres + 0.6 litre if the oil cooler is drained
• These figures are for a UK 3 litre version of the 960

If you've filled the car with 7 quarts of engine oil that's almost twice as much oil as should be in the engine. Did you mean pints when you wrote quarts?

If you've filled it with 7 quarts it's overfull. Way too full. Check your oil dipstick - remove it, wipe it clean and then dip the oil level. At the bottom of the dipstick there is a flattened wider part. The oil level should not be below the bottom of this marker, and nor should it be above it. If the oil level is way above the flattened marker bar - you're overfull and will have to drain some oil out of the engine. An overfilled engine will try and blow oil out from wherever it can as the oil system will over-pressurised.

Ok .. so there's no problem with the engine compression. The crankcase isn't overfilled with oil (the crankcase is known as the oil sump in the UK). There's no oil fouling of the plugs and the car isn't burning oil, just leaking it. There's no misfires or running

If the engine isn't overfilled with oil there may be a problem with a broken/sticking piston ring or piston/cylinder. That high oil loss you mention seems severe. A problem with a piston/ring/cylinder can allow the compression to leak past the rings/piston into the engine oil sump and pressurise it. Under pressure, the oil will try and leak to atmosphere from anywhere it can.

A blue smoky exhaust is also an indication of piston/ring problems. A quick check is to start the car. If there's a cloud of blue smoke at start up which clears quickly, it's like to be worn valve guides. If, when driving the car with a warm engine there's blue smoke on acceleration - it points to a problem with rings/piston.

A quick check is to remove the spark plugs. Is there engine oil on one or more of them? An oiled up plug indicates that the engine oil is finding its way up past the rings/piston - and if oil can find its way up to a spark plug, then exhaust gasses/compressed fuel/air can find its way into the engine oil sump and pressurise it.

Another quick check is to start the engine and remove the oil dipstick. If fumes are 'chugging' out of the tube or oil is spitting out, that's another sure-fire sign that the oil sump is becoming pressurised due to a piston ring/piston/cylinder problem.

If you possess or can borrow an engine compression tester there is a further test you can do yourself to confirm whether or not there are piston/ring problems. Basically, a compression tester is just a gauge that screws into the cylinder head in place of the spark plug.

Warm the engine for 5 minutes so that the pistons expand fully in the bores.
Remove the spark plugs
Fit the compression tester into No1 cylinder and crank the engine for 10 seconds. Make a note of the compression reading on the gauge.
Do the same for each cylinder.

Here's an example of what you might find (the figures are for example only)
Cylinder Reading
1 115
2 120
3 118
4 95
5 96
6 117

Figures vary, but there should not be more than a 10% difference between the readings.
In the example above you can see that cylinders 4 and 5 have readings that are well below those of the other cylinders. This is indicating problems within those two cylinders. The lower compression could be due to a head/gasket fault or piston ring/piston problem. A split or worn exhaust valve in the head may cause low compression, a misfire and uneven running but it won't cause the engine oil sump/crankcase to pressurise. Now, some fine tuning to locate the exact problem:

Put a liberal squirt of oil into each cylinder - something like Redex, WD40 or engine oil.Put a cloth over each spark plug hole and spin the engine to get rid of the excess oil. The idea is that the oil you have squirted into the piston bores will form a 'seal' around the outside of the piston/rings.

Do the compression tests again and note the readings. If the readings go up significantly it indicates that the rings/pistons/bore has a problem. Readings that go up significantly are due to the oil forming a seal around the piston which raises the compression whilst testing. Here's an example:Cylinder Reading on 1st test 2nd test
1 115 118
2 120 121
3 118 120
4 95 110 Significant rise - more than 10%
5 96 98
6 117 119

Ok .. all this means is that cylinder 4 has compression problems due to the rings/piston/bore. The 2nd compression reading (with the oil squirted in) is higher simply because the oil formed a seal. Cylinder number 5 still has a low reading which didn't increase significantly on the 2nd 'wet' (when oil is added) test. This suggests that the problem is an exhaust valve/head gasket/head problem.

If there had been no significant increase in the reading on number 4 cylinder, this would suggest valve/gasket head problem. Low readings on adjoining cylinders (and which don't increase with the 2nd compression 'wet' oil test) would indicate a faulty head gasket between those two cylinders.

I'll continue this article ... ran out of word space