Yanmar 6LPA STP Problems : 4 Known Issues (Solved)

Boats and yachts run on different kinds of engines. There are various brands and models. Yanmar makes a wide range of boat engines one of which is the Yanmar 6LPA STP. The Yanmar 6LPA STP boat engine is a good engine but with its own set of common problems. We shall be looking at some of those common Yanmar 6LPA STP problems.

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What Is The Yanmar 6LPA STP?

The Yanmar 6LPA STP is a boat engine. The Yanmar 6LPA STP has a rated output of 232 kW and a rated speed of 3800 RPM. The Yanmar 6LPA STP is a 6 cylinder, turbocharged, and intercooled engine. It features mechanical controls. The Yanmar 6LPA STP also has quite a number of certifications. Some of them are RCD 1, IMO Tier 2, EPA Tier 2, BSO II, EMC, and SOLAS.

Yanmar 6LPA STP Problems

The Yanmar 6LPA STP boat engine obviously has various moving parts. That alone makes it inevitable for problems to occur sometimes. The Yanmar 6LPA STP engine is a powerful engine. However, you must know some of the common Yanmar 6LPA STP problems. This will streamline your user experience as you will be able to avoid and or address them. Here are some of the common Yanmar 6LPA STP problems:

1. Overheating

This is a common Yanmar 6LPA STP problem. You will usually know the problem is at play when a high temperature alarm sounds. This will indicate that there is an overheating problem with your Yanmar 6LPA STP engine. Some of the possible causes of the problem are:

  • Low coolant level
  • Leakages in the cooling system
  • Contamination in the cooling system
  • Cooling pump may be damaged or faulty

Troubleshooting Overheating Problem

When your Yanmar 6LPA STP experiences an overheating problem it should be fairly easy to diagnose. This is because the problem often stems from the cooling system. Conduct some checks to ascertain the root cause. Some of the solutions you can explore here are:

  • Top up or replace coolant
  • Plug or fix leakages in cooling system
  • Get rid of dirt, debris, or any contaminants in cooling system
  • Fix or replace cooling pump

2. Low Engine Pressure

This is another common Yanmar 6LPA STP problem. It is not desirable for your Yanmar 6LPA STP engine’s pressure to be too low. Yet this is a problem you may encounter. Some of the probable causes of low engine pressure are:

  • Low engine oil
  • Contaminated engine oil
  • Engine oil filter could be damaged or leaking
  • Engine oil filter may be clogged

Troubleshooting Low Engine Pressure

This is also a Yanmar 6LPA STP problem that is often easy to diagnose and fix. The problem usually stems from engine oil-related issues. Do your inspections with that in mind. Once you have narrowed down the possibilities, you can consider the following remedies:

  • Top up or replace engine oil
  • Plug, fix, or replace engine oil filter
  • Flush the engine oil filter

3. Engine Is Not Starting

This tends to be a common Yanmar 6LPA STP problem. At times the starter motor fails to operate at all. Then in some cases the starter motor runs but the engine fails to start. Some of the possible causes of this problem are:

  • Insufficient or incorrect fuel type
  • Fuel filter could be clogged
  • Fuel injection is faulty
  • Compressed air leakages

Troubleshooting Engine Is Not Starting Problem

You have to conduct the necessary checks to figure out the source of the problem. Check the fuel, the fuel system, and other related components. Some of the solutions you can explore for this Yanmar 6LPA STP problem are:

  • Top up or replace fuel
  • Flush or replace fuel filter
  • Fix fuel injection
  • Plug leakages in intake or exhaust valves; or replace the valves

4. Excessive Smoking

Your Yanmar 6LPA STP engine may begin to excessively smoke. The type of smoke being emitted could be white smoke or black smoke. Either scenario is a problem and must be addressed. Some of the causes of this Yanmar 6LPA STP problem are:

  • Overloaded engine
  • Air cleaner element may be clogged
  • Fuel type may be incorrect or may be contaminated
  • Fuel injection could be faulty or timing could be wrong
  • Valve clearance may be too big

Troubleshooting Excessive Smoking Problem

It is fairly common for one to experience their Yanmar 6LPA STP excessively smoking. The problem can be correctly diagnosed and addressed if you do thorough checks. You must narrow down the possible causes then explore the following solutions:

  • Reduce engine load
  • Clean air cleaner element
  • Replace fuel with clean and correct type
  • Fix or adjust fuel injection timing
  • Reduce intake or exhaust valve clearance

How To Avoid Yanmar 6LPA STP Problems

Regular routine maintenance of your Yanmar 6LPA STP engine is important. You must regularly do things like oil changes or greasing. You must also get your Yanmar 6LPA STP serviced as per schedule. Use the correct products e.g. fuel and oils. There should also be times where your Yanmar 6LPA STP engine must be thoroughly cleaned. Conduct regular routine engine inspections as well. All of the above will help avoid Yanmar 6LPA STP problems.

How Much Does The Yanmar 6LPA STP Weigh?

When the Yanmar 6LPA STP is full or complete i.e. with the 8 degree down angle hydraulic gearbox, the whole engine weighs 994 pounds. That is dry weight. By the way, the Yanmar 6LPA STP engine measures 50 inches by 28 inches by 32 inches.

What Is The Average Lifespan Of A Yanmar Diesel Engine?

Typically, a Yanmar diesel engine should last as long as 10000 hours or more. That will largely depend on usage dynamics and routine maintenance.


Avoidance of problems and longevity for your Yanmar 6LPA STP engine are borne out of responsible use. For instance, every 2000 hours, the injectors need to be rebuilt or recalibrated. The same applies to the injector pump but it should be done after 5000 hours. Doing those routine maintenance processes is what makes your Yanmar 6LPA STP engine perform better and last longer.