The marine engine repair is your first line of safety you depend on. Engine Repairs Marine inboard outboard repowers, over-hauls by a real marine engineer. Enginemans email direct 619-218-1018
san diego marine engine repairman doing
marine engine repair and 
marine mechanic in san diego for marine engines only • low cost marine engine repair by 30 yr.marine mechanic all here in san diego by Greg Moore marine engine repairs. 

Marine Engine repair San Diego Since 1986 Questions to Marine engineers direct email

Greg always has said he loves fixing marine engines. He says it goes by to his days watching dad and grandpa fix engines on the farmin Indiana.  "Sure its dirty and nasty smelling." Greg says. " Repairing a marine engine is very hard on your muscles and you have to be extremely organized and carefull you dont make a mistake. Thats why I like doing marine engine work, its very challenging and the customers really like it when not just the engine problems get solved but thhey love that i can build entire boat and systems. " 

 It also takes a comittee of peers and experts to make a good engineman the best engine repairman. Boat mechanics consult with specialist who take their calls at all hours. A mechanic who knows everyone in the engine industry is of great value to a boat owner.

Before the job begins, you have to protect the boat by making sure fluids dont get into bilges and then go over board. You have to protect your flooring and cover anything a mechanic can get his dirty hands and clothes onto. 

 You have to know transmissions and heat exchanger and closed loop cooling systems. You have to know all the electrics and controls, even fly by wire systems like mmcs, or glenn dinnings. You must know the sensors, the alternator and starter, batteries, for newer engines, the data buss, the engine manufacture specs and be able to do the marinization and intergrate the engine into the fuel system, oil changer system and drive shaft alignment. 

Then when you get every done, you have to load vessel shaft up speed to temp and rpm and ensuire your getting all the horse power into the water. Some engines have demanding exhaust systems and alot of naval vessels have shock and vibration mount requirements and navy regs that take you into the stratospere of marine engine science and inspections. 

Things take time, you cant always work real fast doing engines and sometimes repeat trips to get correct part or trying a repair to see if problem is eliminated and perhaps finding it didnt fix the problem and you still have more to do. Disposing of oils and fuel is hard too. 

All these challenges and Greg comes to you, yet cost you less than taking your car to dealer. 



The most common internal combustion engines of today can be defined as either four-stroke or two-stroke cycle. Two-stroke or four-stroke refers to the number of strokes the piston makes in the cylinder to complete one power cycle. A stroke is the movement of the piston in one direction, moving the piston from the top to the bottom of the cylinder is one stroke. A running internal combustion engine continually repeats a power cycle called: intake, compression, power and exhaust. Your automobile or stern drive engine is most likely a four stroke design. The majority of existing outboard motors use two stroke technology. However the current movement in emissions regulations is pushing the design of current outboards towards the 4 stroke and direct injection two stroke design. Efforts to build a 4 stroke outboard in the past have been many and varied, mostly unsuccessful as the design technology and precision production that can be achieved today were impossible to achieve then. Resulting motors were bulky and unreliable. Those motors that were viable were for the most part rejected by the boating public.

Section One


The first description reviews the operation of the 4 stroke power cycle. Each 4 stroke image depicts a piston in a cylinder, a spark plug and 2 valves; one intake, one exhaust. The valves are held closed by means of a spring and opened by a rotating eccentric called a camshaft. The camshaft is driven from the crankshaft by means of gears or a drive belt and timed to the up and down movement of the piston. To complete all 4 strokes the crankshaft makes 2 revolutions.



Intake Stroke


As the piston is pulled down during the intake stroke, The camshaft opens the intake valve and a fresh charge of fuel/air mix is drawn into the cylinder. The intake valve closes when the piston reaches the bottom of its downward stroke.

Compression Stroke


The piston now begins to move upward and starts to compress the air/fuel mixture in the cylinder. Both valves are closed. This continuing upward motion compresses the mixture to about 100-120 PSI, around 7 or 8 times atmospheric pressure (the compression "ratio"). As the piston reaches the top of the cylinder the spark plug fires and ignites the compressed mixture.

Power Stroke


The fuel air mixture now BURNS very rapidly, increases in pressure generated by combustion force the piston downward in the cylinder. Both valves are still closed. This is the only stroke that creates power in the 4 stroke cycle.

Exhaust Stroke


Upon completion of the power stroke the piston starts to move upward again and now the exhaust valve starts to open. The continuing upward movement forces the hot burned gases out past the exhaust valve. When the piston reaches the top of the cylinder the exhaust valve closes. The piston starts to go back down and the cycle repeats itself.

The advantage to the 4 stroke is that the combustion process is very efficient at varying RPM ranges with almost no unburned fuel escaping into the atmosphere. 4 stroke engines also develop significant torque at low Rpm's. The big drawback is there is only one power stroke for every 2 revolutions of the crankshaft so the engine lacks the burst of power experienced with the 2 stroke engine. Four strokes are more complex as well as generally much heavier as a result of additional parts, e.g. camshaft, valve train, balance shafts, etc. required to complete the power cycle. This additional complexity does not reduce the engine's reliability. Four strokes have a proven track record in reliability and dependability.

Next, let's review the two stroke theory of operation and examine the various types of these engines and how they work.


Outboard carburetion systems are generally pretty rugged and reliable. Unless you have many running hours on a modern outboard, this system gives little trouble.

Older, pre alcohol fuel days motors have fits when presented with " extended " fuels and should you have one of these I strongly recommend you upgrade the fuel system components.

The worst enemy of fuel systems is the fuel itself left to spoil in the unused motor. Proper preparation for storage of motors in seasonal climates is a MUST to avoid this nasty problem. Here is my storage tips page.

If your engine is suffering from a suspected fuel problem, here's how to check for dirt in the carbs. You will find a screw in the lower portion of the float bowl on almost all outboard carburetors, generally the main high speed jet is located immediately behind this. On Chrysler/Force concentric bowl carburetors you will have to take the float bowl clear off to look. IF there is white powder or jellylike translucent gleep you have water that has been sitting in the fuel system, the carburetor will have to be cleaned and the source of the water isolated and corrective action taken.

Plain clear water indicates only that you need to find out where it came from as above. Shouldn't hurt it any, but small low speed passages may have water in them as well and you will have to clear them with compressed air.

Find brown goo, brownish or greenish deposits or some stuff that looks like tree sap, you have a case of varnish and will need to examine ALL the lines as well as the fuel pump diaphragm for deterioration from the bad fuel. It eats everything.

VARNISH Varnished bowl

I have found the use of OMC Engine Tuner will clean the carbs without exposing you to caustics, has no unpleasant odor and it rinses away with water. Similar products are available from other manufacturers.

Many of today's modern engines have some sort of oil premixing or injection system, you need to examine this system closely as well. If you are experiencing excessive oil usage on an Evinrude or Johnson equipped with the VRO system, look for an air leak on the fuel side. Air leaking will cause the oil side to add too much for the imaginary gas that is actually air.