Removing Diesel Adding Outboard

Thanks Bill

Is the cylinder block seperate from the crankcase? Can I reassemble the pistonand rings into the liner with out removing the engine?

Thanks.

I had the same thing happen recently, but unfortunately I had more to do than replace a head gasket. What had happened was: The head gasket became compromised when rust particles from the head broke loose and plugged the cooling water exit at the point where it joins the exhaust elbow causing over heating. After the event,the engine ran, but a small amount of moisture got into the cylinder via the head gasket. This froze the piston rings down into the grooves in which they are situated, preventing their outward spring action to engage the cylinder walls.....hence, no compression, and engine would no longer function. This required more work leading to my pulling the engine, going through everything, and while doing so I honed the cylinder walls and installed new rings.

However, compression can also be compromised if the valves are not seating. This may require valve grinding, but first pull off the valve cover and check the clearance on the rocker arms to see if there is .20mm on the intake and .25mm on the exhaust side. If there is no clearance at all, then the valves will not come own and seat. I doubt this is your problem. Also check to torque on the injector hold-down bolts/nuts.

Also, before starting anything, you should just check the tension on the head hold-down nuts which also hold the cylinder block in place. The workshop manual suggest these be checked periodically.

When you go to remove the head in-situ, after the nuts are removed, do not go at the gap between the head and the cylinder block with a screw driver and hammer to pull them apart. You could try an aluminum wedge and hammer, but if none of that works, then:

1. Remove the injector nozzle.
2. Stick something down the hole to find the top of the piston and then rotate the flywheel until the piston is in the bottom position.
3. Fill the cylinder with gear oilvia the injector nozzle hole.
4. Replace the injector nozzle.
5. Loosen the hold-down bolts retaining the head a few turns.
6. Crank the engine over with the battery and key. This will pop the head off without you scaring the faces of the cylinder wall and the head on the first turn.
7. Clean up the spilt oil.

To reduce mess, one may not have to fill the entire area with oil, but I have not tried it that way. The piston actually raises at the top just above the actual top of the cylinder, into the gap created by the head gasket, so there is not much volume when the piston is at the top. I should think that maybe only an inch of oil on top of the piston will do. Of course, if all the rings are siezed down, then this may not work, or will require more oil. I suggest using 90 weight gear oil for this to better your chances if any of the rings are compromised.

If you don't have one, download a copy of the workshop manual for this engine before starting. It is much more comprehensive than the owner's manual. You can find it if you Google around a little. If you can't find it, contact me and I will send it to you in pdf.

When the head has been pulled, you can also remove the cylinder block to see the condition of the rings. If they are all a mess, but no scoring or grooves are evident, you could just at that point remove the piston, clean the ring grooves, and replace the rings, however by this time a lot of work has been done and it may pay to remove the engine and go through it on the bench. I chose the latter as at 63, and with no discs remaining in any of my lumbar area and all lumbar vertebra degenerating, I have limited ability to work in those spaces for very long.

If you elect to remove the engine, and if you have two windows in your cockpit (a Laser option, contact me for an easy procedure I've worked out to get the engine out without much effort or pain.

Good luck.

Can the head gasket be replace while the motor is still in the boat. Rapscallion has a low C/R (very easy to crank ovr). We don't see water in the oil and all other indication are the otor is good, just no compression.

thanks for the pictures-very nice work. A freshwater cooling system gets rid of one of the Bukh's 2 big problems-dissimilar metals being one and the lack of an oil filter the other.

From 4" stock T-6 aluminum, I turned a pulley for an A-section best that fits to the top of the flywheel via the flywheel hold-down nut. On the port side of the engine, if you look closely, you will see several female threaded bosses that take an 8mm bolts or threaded studs. These were used to bold in place a piece of 3/16" x 3" angle aluminum, trimmed to fit such that the top L comes directly under the alloy plate portion of the crankcase just below the flywheel. To this I bolted another 3" x 3" angle to provide vertical surface to which I bolted the second pump. I used an Obedorfer centrifigul with pedestal base for this. From the 4" stock, I turned another pulley to fit onto the pump and trimmed it down to 3 1/2" diameter. This was not to gain more pump rpm, but to give more clearance to the sliding hatch door on the port side quarterbirth. An A-section 27" belt connects the two pulleys that I mounted high enough above the flywheel so that one could still use the rope pull start on the flywheel if necessary. To allow clearance for the knot of the pull-rope, the belt clears the top of the flywheel by about 5/8" or 30mm. I have photos of this arrangement that I would be happy to send if you provide me with your email address.

San Juan Engineering made the heat exchanger with integral expansion tank. It is 9" long, and about 3" in diameter. It fits to the front of the engine directly behind the access stairs. On the front of the engine there are 4 studs (either 6 or 8mm) that fix the steel mounting bracket to the engine. I replaced these studs with longer studs so that the studs could be used to also hold two pieces of 1/4" x 2" pieces of aluminum situated vertically on which to mount the tank, where the radiator cap must become the highest point of the cooling system.

I used the Bukh's own Johnson pump to circulate the raw water that now comes from the sea, to the heat exchanger, and then back to the regular cooling water outlet fitting at the exhaust elbow.

The centrifugal pump circulates the coolant pulling it off the bottom of the heat exchanger, driving it to the engine up at the thermostat area just the way the raw water used to go, and then back into the top of the heat exchanger.

That's it! If you supply me with an email address, I will send some pics which are a better explanation of it.

To bring you up-to-date on Andiamo, the Bukh was removed this spring and the block and head are corroded from the 25+ years in seawater. I sold the engine and saildrive to a fellow clubmember for spares. There is a discussion on the removal of the engine, which I read AFTER removal. I was able to manhandle the engine out of the boat using block and tackle. I epoxied a backing plate of 3/4" plywood to the stern on the inside and mounted a heavy duty mount for the 9.8 longshaft Nissan 4-stroke. This engine has remote controls for starting and shifting. I mounted the remote in the starboard lazarette. The prop was changed to a low speed prop, yet I get 25% more speed, especially in headwinds. Now there is no oil in the bilge, more storage and no drag. We race PHRF so no issues. So far - so good!

I'm not sure about the states, but parts can still be obtained via Crinmar Marine in Kingston, Ontario (Keith Strutt), and the UK agent. Both of these people are knowledgeable. I don't know what is wrong with your Bukh, but unless you dropped it from a 10 storey building the type of parts that it is likely to need should mostly be able to be fixed. Replacement bits such as rings are actually manufactured in Italy by another company and those rings clearly fit other engines as well, so they will continue to be available. Bearings, likely unnecessary, are mostly generic as well as are the seals. The head (and head gasket)that houses the valves, etc, is a critical piece and if it becomes to badly corroded such that it cannot be repaired, then that item is truly a Bukh part and will not be found elsewhere. Looking at the head of my engine is what drove me to converting it to freshwater cooling via a heat exchanger. That is not a very difficult conversion and I'm happy to help anyone interested in pursuing that path.

saildrive280.com doesn't exist anymore. It hasn't for a while now. If you read post #2 in this thread you'll see that a 6hp 2-stroke worked very well. It not only got the L28 to hull speed it did it in a good sea as well. And this was with a regular shaft and prop. Needless to say with a long shaft and the available high pitched sailboat prop it would perform even better. This outboard weighed 60 Lbs, whereas the 4 stroke version of the same weighed a little over 100 Lbs. Which I'm assuming is why the Farr25 comes with a 2-stroke only, maybe for compartment size reasons as well. But as frfletch mentions above the range with a diesel is incomparable to any gas power engine

Edited by Bill Layton - 08 October 2010 at 10:29am

Why go away from the Bukh? This is a great little engine. I just rebuilt mine and converted it to fresh-water cooling with a heat exchanger. I have used outboards before, but if you are using it for any more than getting to and from the race starting line, the diesel is far better.