Christmas had a Chrysler Nissan diesel installed in 1974 by the previous owner. After 8 years, I've found it to be a good engine. It's always smoked a bit and the last year started serving notice, even after replacing the injectors, that it needed attention. After some diagnosis, I decided it was general deterrioration due to age.
One of the problems with old boats is, stuff wears out. So what to do? I decided to look into rebuilding. I was happy with the engine and a I estimated a total repower to be more money than we needed to spend for how we use the boat. Also, as I would be doing the work myself, time involved in changing all related systems would at least equal the cost of the replacment in materials and my labor.
All parts are available for this engine to rebuild. So I went looking for a rebuilder. That turned out to be the problem. As a generally unfamiliar marine engine, I couldn't find someone locally I was confident in for the task. Many of these 4 cylinder Nissan SD-22 diesels were built from 1963 through the 80s. The original blocks was designed for industrial applications, generators, water pumps, etc. They were also used in forklifts (still are) as well as getting a marinized version by Chrysler. And then in 1981, Nissan offered the engine as an option for their pick up trucks. In my search for a rebuilder, I was directed to a Nissan mechanic. To make a long story short, he could not rebuild my SD-22, but he happened to have one at his shop. While at the dealership he serviced a lightly used truck from new and when the body rusted out after 70,000 miles, he bought it from the owner to use the engine in some sort of project. 6 years later, the project never happened. After hearing it run and checking it out, I bought it from him (1,000.00)
A used engine is a gamble but this one, with it's apparent history, seemed like a good choice. So far, this has been fun to do and highly educational as well. Pulling the old was quick and easy using the local yard crane. Once in my garage, I started removing the parts I would not need and refurbishing the marine parts I would reuse.
Compared to the compartment on a boat, working on an engine in a shop is a joy. Here, the old engine is hanging as the new waits on the floor behind.
The post mortum of the old engine revealed the surprising problem. In taking it down to the block, I noticed an odd play. When at top dead center, I could rotate the crankshaft a suspicious 5 or so degrees, left or right, without the timing gears moving. Upon taking the forward shaft nut, pulleys, sheeves, etc, there it was. The Woodruff key and keyway which is used to align the timing gear during assembly, had worn and elongated the slot to allow a pivoting of the key (shown in this photo with keys removed). Research found, the nut cones and washer must not have been correctly re-assembled at some point or under torqued which allowed this to happen. Of course, this would throw off the timing resulting in smoking. Sadly, the rest of the engine, cylinders and all, were in good condition.
Now that needed gaskets have arrived, I'll put the "new" engine together and drop it in my truck to take to the boat. This time has allowed me to clean up the engine compartment and apply some fresh paint to the area.
But before I put the replacment back in, I need to replace my cutlass bearing. With the engine out, I pulled the prop and slid the shaft out. I haven't removed the old yet, but I have yet to find a set screw on the original stern bearing. A nice set up all threaded bronze tube up through the stuffing box. I'll sand it down which may reveal the set screw(s). I notice what may be a dimple set by a drift on the end of the bearing. Could this have been how these stern bearings were designed?
Now that the cutlass is removed, I can answer my own question. There were no set screws in the bronze stern tube. The dimples turned out to be small machine bolts. Two pilot holes were drilled parallel to the shaft into the stern tube and cutlass bearing mating area. The small machine screws are then turned into this pilot hole. The threads engage both the stern tube and the cutlass bearing to keep it in place. After replacing, a few light sets with a punch over the small machine bolts locked them tightly.
Removing the cutlass bearing took careful sawzall and chisel/prying work. The stern tube which is bolted to the bronze shaft tube, has a recess milled in to receive the 1 5/8" x 4" cutlass bearing. (I had to cut flush a 4 1/2" bearing) There's no way to press it out.
One of the problems with old boats is, stuff wears out. So what to do? I decided to look into rebuilding. I was happy with the engine and a I estimated a total repower to be more money than we needed to spend for how we use the boat. Also, as I would be doing the work myself, time involved in changing all related systems would at least equal the cost of the replacment in materials and my labor.
All parts are available for this engine to rebuild. So I went looking for a rebuilder. That turned out to be the problem. As a generally unfamiliar marine engine, I couldn't find someone locally I was confident in for the task. Many of these 4 cylinder Nissan SD-22 diesels were built from 1963 through the 80s. The original blocks was designed for industrial applications, generators, water pumps, etc. They were also used in forklifts (still are) as well as getting a marinized version by Chrysler. And then in 1981, Nissan offered the engine as an option for their pick up trucks. In my search for a rebuilder, I was directed to a Nissan mechanic. To make a long story short, he could not rebuild my SD-22, but he happened to have one at his shop. While at the dealership he serviced a lightly used truck from new and when the body rusted out after 70,000 miles, he bought it from the owner to use the engine in some sort of project. 6 years later, the project never happened. After hearing it run and checking it out, I bought it from him (1,000.00)
A used engine is a gamble but this one, with it's apparent history, seemed like a good choice. So far, this has been fun to do and highly educational as well. Pulling the old was quick and easy using the local yard crane. Once in my garage, I started removing the parts I would not need and refurbishing the marine parts I would reuse.
Compared to the compartment on a boat, working on an engine in a shop is a joy. Here, the old engine is hanging as the new waits on the floor behind.
The post mortum of the old engine revealed the surprising problem. In taking it down to the block, I noticed an odd play. When at top dead center, I could rotate the crankshaft a suspicious 5 or so degrees, left or right, without the timing gears moving. Upon taking the forward shaft nut, pulleys, sheeves, etc, there it was. The Woodruff key and keyway which is used to align the timing gear during assembly, had worn and elongated the slot to allow a pivoting of the key (shown in this photo with keys removed). Research found, the nut cones and washer must not have been correctly re-assembled at some point or under torqued which allowed this to happen. Of course, this would throw off the timing resulting in smoking. Sadly, the rest of the engine, cylinders and all, were in good condition.
Now that needed gaskets have arrived, I'll put the "new" engine together and drop it in my truck to take to the boat. This time has allowed me to clean up the engine compartment and apply some fresh paint to the area.
But before I put the replacment back in, I need to replace my cutlass bearing. With the engine out, I pulled the prop and slid the shaft out. I haven't removed the old yet, but I have yet to find a set screw on the original stern bearing. A nice set up all threaded bronze tube up through the stuffing box. I'll sand it down which may reveal the set screw(s). I notice what may be a dimple set by a drift on the end of the bearing. Could this have been how these stern bearings were designed?
Now that the cutlass is removed, I can answer my own question. There were no set screws in the bronze stern tube. The dimples turned out to be small machine bolts. Two pilot holes were drilled parallel to the shaft into the stern tube and cutlass bearing mating area. The small machine screws are then turned into this pilot hole. The threads engage both the stern tube and the cutlass bearing to keep it in place. After replacing, a few light sets with a punch over the small machine bolts locked them tightly.
Removing the cutlass bearing took careful sawzall and chisel/prying work. The stern tube which is bolted to the bronze shaft tube, has a recess milled in to receive the 1 5/8" x 4" cutlass bearing. (I had to cut flush a 4 1/2" bearing) There's no way to press it out.
