Tag Archives: Yanmar


It is recommended to check the alignment once/year as the rubber in the engine feet ages.  Another reason for misalignment can  be that the locking nuts came loose.

Signs of misalignment :

  • Vibrations
  • Wear on cutlass bearing’
  • Leaking stuffing box
  • Loose bolts in shaft coupling

Center the shaft in the stern tube:

Engine should be aligned to the shaft.  Not the opposite!  To do that you need to fix the propeller shaft in the center of the stern tube.

A common way fixing the shaft  is with the use of 4 small wedges.  On an HR 43 it is not easy to get down to the shaft tube with both hands.  Holding 4 wedges in place and at the same time moving the shaft back and forth takes more than two hands.  Two persons in the engine room is not an option.

I had a workshop do a fixing tool in delrin.    (Drawing Shaft plug)

Fixing tool

Fixing tool

Shaft fixed in the stern tube.

Shaft fixed in the stern tube.

With the tool, it was easy to center the shaft in the shaft tube.  Even if you are not considering doing the alignment yourself,  I recommend that you carry the tool onboard.  The mechanic will most probably not have the tool, and try to do the job  anyway.  If the shaft is not fixed and centered, it is a risk that the shaft will be aligned to the engine instead of the opposite.

Align engine to the shaft!

Make sure you have the necessary tools to loosen the nuts on the engine mounts.  A crowbar can be handy when you have to move 200 kg engine sideways.

You can start with just eye baling the alignment.  Move the engine around until it looks good.  

When it looks O.K., it is time to measure.  Turn the shaft coupling around and  measure the distance up and down and on both sides between coupling and flange for gearbox with a feeler gauge. When it is whit-in 0.005 mm it is O.K.

Centaflex is a flexible coupling.  In the documentation it is said to be able to take up two degrees misalignment.  The local Centaflex dealer did not agree about that statement, and recommended to do the alignment as good as possible.

If you end up to high on the bolt for the engine mount, there will be more vibrations and load on the bolt.  It is recommended that you can see at least 5 mm thread on top of the locking nut.  If not you should put shims or pads between the mounts and the engine foundation.

Need to install a higher aluminum block under the engine mount. On the to do list.

Need to install a higher aluminum block under the engine mount. On the to do list.

If your boat has an Aqua-Drive unit it is important to know that you should not have perfect alignment.  With an Aqua-Drive you should have app. 2 degrees misalignment!  If not the bearings will not be lubricated and will wear out.



If you have a Yanmar engine and have been reading the manual,  I´m sure you know that the elbow (Riser) on the exhaust of the engine should be cleaned every 250 hours or once/year.

I got this picture from a friend with a Hallberg-Rassy 34.  As you can see the elbow is plugged to   98 %. Only a small hole left.

Plugged elbow on a Volvo Penta 2030

Plugged elbow on a Volvo Penta 2030

The exhaust elbow is living a tough life, and is one of those parts that will have to be replaced on most engines.  The exhaust elbow is the mixing point of very hot exhaust fumes and salt water.  A very hot and corrosive environment with carbon deposits.  (Another reason you should do the Italian tuning)

Volvo Penta does not mentioned anything about inspection in their manuals.  Nevertheless,  I recommend that you include a check of the elbow independent of the engine manufacturer.


Everyone that has had to dismantle the heat exchanger to find parts of a broken impeller will appreciate the SPEEDSEAL LIFE.  It is an ingenious product that solves three possible problems with the water pump on a marine engine.

Running dry

All it takes is a plastic bag in the water intake.  Seconds later the impeller over heats and break apart.  As a result you might have to dismantle the heat exchanger and try to clean it from broken impeller parts.

With SPEEDSEAL LIFE  you can run the water pump dry for much longer than it takes to get a high temp. warning from the engine, whiteout damaging the impeller.  The Yanmar importer in U.K. ,  EP Barrus did a test 4 Years Experience Test with the SPEEDSEAL LIFE.

After  running the impeller without water for 10 times x 10 minutes (100 minutes!) the impeller did not show any signs of damage.  In real life you get a high temp. warning from the engine  and can clear the intake and continue without having to open the water pump or the heat exchanger.

Cover plate with discs

SPEED SEAL LIFE Cover plate with the 2 discs

Cover plate with teflon disc in place

SPEEDSEAL LIFE Cover plate with teflon disc in place

Fully assembled Speedseal Life

Fully assembled SPEEDSEAL LIFE  ready for action

Wear on the cover plate

Take a look at the inside of the original cover plate next time you change the impeller.  I´m sure you will find scars/wear from the impeller.  How much depends on engine hours and water quality.  When the scars are deep enough, your pump will not pump enough with water.  With SPEEDSEAL LIFE  you can change the bearing disc (wear plate) in seconds.

Damaged cover plate

Damaged cover plate (250 engine hours)


The SPEEDSEAL LIFE comes with four screw knobs that replace the standard screws that hold the cover plate to the pump house.  Normally the water pump is in a awkward position which makes it difficult to use a screwdriver.  With the knobs no tools are necessary.

If there was a “product of the year award”  in the marine business, it would get my vote.  Highly recommended, both for the engine and generator.

Speedseal life with knobs


The SPEEDSEAL LIFE comes in a kit that even includes a tool for removing the impeller.  When ordering I suggest that you include some spare bearing discs.

Do not forget the generator.  The risk for sucking up plastic bags etc. is much higher if you are not moving.