Replacing the turbo and servicing the oil cooler

Looking over the turbo and exhaust at the beginning. The wrapping in front is the thermal jacket around the mixing elbow. The mixing elbow is where the exhaust gases and cooling water merge and go into the muffler.  

Several months ago we began experiencing issues with our engine and it wouldn’t go over about 2400 RPM and around that range it began producing heavy black smoke. The first thing I did was clean the air intake and change fuel filters. Our injectors were only a year old with about 200 hours on them. We checked them and they were working fine. Next, we inspected both sides of the turbo and the fans seemed to be turning ok. We checked the exhaust and that wasn’t restricted. We checked the valves opening and closing and later adjusted them. We checked the back pressure on the turbo and it was normal. The prop and bottom were clean and unrestricted. I talked to several different people and the guess it was the fuel injection pump. So I had it removed and took it to Florida and had it rebuilt at Everglades Diesel Injection Service in Fort Lauderdale.

We brought it back with us and had it reinstalled but it did not fix the problem.

 

View of the connection between the heat exchanger and the turbo. The braided hose carries coolant from the turbo to the heat exchanger. That part is apparently not a Yanmar part and I have yet to find a source for it. The black exhaust hose carries the seawater to a vented loop and the mixing elbow. Above it is the oil connection between the oil cooler and the turbo,

After talking with several other people and smart Yanmar people the conclusion was that it was the turbo and it should be rebuilt. There are turbo shops here in Panama that could rebuild it but I wanted to get a Yanmar kit instead of having cheap parts installed. In the process of getting that kit I was directed to a Yanmar dealer in Panama City. He had a “clean” turbo that he could install on our engine and then have ours rebuilt. So we discussed costs and logistics and he flew out for a day and we discussed options. He didn’t install his turbo and we agreed to buy a new one. However, after our discussions and agreements he decided he wanted to charge us more. I had already paid him for the day and a deposit on the turbo. After his new invoice at higher rates I cancelled his efforts but bought the new turbo. As a result, I had a new turbo with nobody that I trusted to install it.

This is Page 10 of the Parts Manual showing the exploded view of the assembly that I used to disassemble and reassemble the turbo.  

After talking to some other people, reviewing the manuals and watching some Youtube videos I decided that I would do it myself. It seemed pretty straightforward, and I wouldn’t be paying a lot of money for bad work. I could mess it up as badly as anyone else and would have only myself to blame. As it turned out it went about as I expected and the engine is running fine with no leaks. So here is the step-by step of how to replace the turbo and service the oil cooler. Since I had to redo the oil cooler to fix a leak, I figured out how to remove the oil cooler without removing the turbo. Something I thought difficult if not impossible before I started. 

Figure 22 from the Parts Manual showing the Sea Water connections in the engine around the turbo and through the Oil Cooler. 

Each item or group that I removed I put into small plastic sandwich bags and marked on it where they go. The locations are fairly obvious but it helped to keep all the hardware organized as I had to close up the engine each night to reload everything into the aft cabin.

The first thing I did was to drain the coolant and raw water by closing the seacock for the engine and loosening the cover to the impeller. I let the oil settle down into the oil pan. I collected the coolant from the sump and put it in a container before I drained the water because then I could just dispose of the sea water overboard. I also removed the insulated cover for the mixing elbow and a metal air duct I have that runs to the side of the engine. It has gotten beaten up badly with all the people in and out of the engine so I need to replace it.

The turbo before disassembly.

 

Next I removed the mixing elbow. There are 3 nuts with washers that attach the mixing elbow to the turbo. They require a 13mm socket. There should be a gasket between the mating surfaces. Ours was firmly pressed against the turbo and I decided to replace it and let the old one stay fast to the turbo.

Then I removed the hoses off the heat exchanger and the mixing elbow by loosening the hose clamps and pulling the hoses off the barbs. There are two lines that go to the vented loop that will also contain water. One from the heat exchanger that flows to the mixing elbow carrying the hot seawater to mix with the exhaust.  The one that goes to the vented loop is a regular hose and the other one that goes into the turbo is braided hose, at least on our boat. Since I can’t find a part number for the braided hose from Yanmar I suspect it is a factory modification along with the straight connection from the turbo. I am investigating further to find the parts. All hose clamps use a 5/16 socket. I was going to replace the braided hose but since I couldn’t find a replacement I decided to reuse the old one. It appears to be in good condition. I will try to get a new piece of braided hose. This carries the coolant from the turbo into the heat exchanger. Because the braided hose is rigid you can’t remove the hose until you remove the turbo.

Showing the mixing elbow in place before disassembly. I initially only removed the elbow from the turbo and stuffed a rag in it to prevent water from flowing back. I later removed the clamps on the muffler that are the same as the ones pictured above. 

Next I removed the oil loop from the top of the turbo housing to the oil cooler. Those two bolts are hollow and have copper washers above and below the oil line. They required a 17mm socket.

Next, I removed the air silencer assembly from the rear stbd side of the engine by loosening the standard hose clamp holding it on and the mounting bolt on the valve cover. The mounting bolt required a 13mm socket. Then the air silencer could be pushed to the front of the engine out of the way.

From page 15 of the Parts Manual showing the oil connections on the turbo and the oil cooler. The connection labeled number 20 was the most difficult one to get off because of the bolt being between the housings of the turbo and the drain pipe number 14.

Next I removed the duct from the manifold and the turbo. It is connected to the turbo with standard hose clamps clamped on to the outlet from the turbo and the duct. The duct is held on by 4 bolts that are 12mm. 3 of the bolts are easy to access with a socket but the bottom inside one couldn’t be reached because of the bend of the duct. Once I got it loose with a box wrench I was able to turn it out with my fingers. Also, once it got loose I could rotate it down for easier access.

Next I removed the coolant return line from the port bottom side of the turbo. The line had a hose clamp requiring a small screwdriver to turn the hose clamp. The line is only ¼” ID and the clamp is very small. The manual calls this a pipe but on reinstallation the end came apart and it is clearly hose. I installed a piece of high grade fuel line to replace it and have a new one on order.

The air silencer connection to the turbo showing the clamp. To remove the silencer simply loosen the clamp.
 

Next to remove the oil pipe connection on the bottom of the turbo is very difficult. The connection is held on by 2 bolts of 10mm. The outside one is easy to access with a socket on a small extension. The inside one required the socket on an extension with a flex connector on a small socket driver. If you don’t have a flexible connecter you should have one in your tool bag.

Finally, to the turbo and it is held on by 4 nuts with washers on studs in the engine of 13mm. 3 of the nuts were fairly easy to access. The bottom inside was able to be accessed with a box wrench. It’s very difficult to get hold of the nuts with your fingers. With the turbo completely disconnected I slid it off the studs and took it out of the engine compartment because the exhaust side was full of soot which I expect was the cause of our issue. 

The oil connection under the turbo with the front bolt circled and the arrow pointing to the rear bolt. That's the one I got with the socket in a 3" extension connected to a swivel connector to the socket driver.
 

The turbo came lacking several connections that were in the old turbo. There is the hose connector that had the braided hose; the studs for the mixing elbow; the elbow for the coolant return line; and on the bottom is a drain cock that wasn’t used on our turbo. After looking at our turbo I decided not to remove and reuse them. Instead I bought new ones except for the braided hose connector because that wasn’t an OEM part apparently. So we did switch that piece. My thinking was that if I need to replace the turbo at some point I might not have a machine shop available to move the connectors. So I will have a full ready-to-go turbo after it’s rebuild and not need any parts for that. We had a machine shop here in the marina where I took the turbo to install the studs and connectors.

At this point I made a parts list to order from the Yanmar supplier in Florida. I ordered new washers (many extra), several critical bolts, gaskets, a new hose that connects the oil cooler to the heat exchanger and only accessible by removing the turbo hoses. So before I could reinstall the turbo I needed to wait for the new parts. 

The new turbo.
 

But I went on to remove the oil cooler so I could clean it. I had new O-rings for it so I didn’t need to wait for them. First I removed the raw water hose between the oil cooler and the heat exchanger. It seemed worn and I ordered a replacement. I was held on by 2 typical hose clamps.

Next I removed the bolt in the top of the oil cooler that serves as a base for the line to the turbo as well as the return line to the oil pan. I did not have a socket large enough so I used a large adjustable wrench to get it off. I then took it to a hardware store and found it requires a 27mm socket or wrench. This was the only tool that I had to buy. Next, I removed the top bolt holding on the outside end cover of the oil cooler and a bracket for that oil line. This was the top outside mounting bolt for the end cap. That was a 12mm bolt like all of them securing the oil cooler.  I loosened the pivot bolt on that bracket so I could turn the bracket out of the way. That was a 10mm bolt. I removed that end of the oil cooler completely. I did not disconnect the water hoses to the transmission. 

The hose connection between the turbo and the duct. It's only necessary to remove the one on the turbo.
 

On the side of the cooler is another hollow bolt that is the incoming oil line into the oil cooler. The bolw is the same size as the one on the top but has a solid head. However, there was not enough room to get the socket and driver in there but I could use a medium-sized adjustable wrench to turn that. Both of these bolts have copper gaskets under the head of the bolt and between the round oil connection and the base on the oil cooler that will fall out when you remove the oil cooler. I replaced all these gaskets with fresh ones.

The oil cooler is mounted with 2 bolts under the outside end into the engine housing and one on the inside to a post also mounted into the engine housing. The one on the inside end is attached to the end cap. Because there is no room to just slide out the core the entire core housing must be removed. So I removed the two mounting bolts from the base. The forward one was easily accessible with a socket on an extension from the galley (I used a 12mm socket on a 3/8” drive extension to get more leverage). The rear one must be attacked from the rear with a box wrench because the oil pipe is right in front of the bolt. At some point after it’s loose the bolt should be removable with your fingers. I then removed the mounting screw in the inside end cap and the 2 end cap screws. All 12mm. With the turbo out the bolts on the inside were easily accessible with a socket or box wrench. 

The turbo with the oil connection removed. On top of the oil cooler is the 27mm bolt.
 

Once all the bolts were removed I had to drive off the end caps with some taps and jiggling. The inside end cap is connected to a fresh water supply hose that is clamped to a pipe from the water pump. The lower clamp can be accessed from the side access door and it is up under the exhaust manifold. I decided not to do that because of the difficulty getting that hose back in. With both ends loose I could lift up the core and the housing and rotate it out.

When I removed the core I put it into a bucket because there was still a good amount of oil trapped inside that was very dirty. The ends of the core were very dirty and had lots of debris pinned to it but none of the tubes appeared to be blocked. I soaked the core in a bucket of vinegar and water with an oil absorbent cloth in it to soak up the oil. I also sprayed degreaser on it to help clean it up. 

Looking at the outside top of the oil cooler with the hoses running down to the transmission and the top bolt holding the oil line bracket.
 

To clean the core of the oil cooler I first soaked it overnight in a vinegar and water solution. I did additional cleaning of the core with degreaser after initial soaking to help break up the oil sludge on the inside of the core. After additional soaking I used more degreaser and rinsed out with a stream of fresh water several times until the discharge was relatively clear. I then used a nylon bristle brush and removed all the scale and dirt accumulated on the ends of the core along with the old O rings that were rotting. Then I propped up the core or an angle to dry and allow any remaining liquid to run out.

With the raw water system drained I looked at the impeller and lubed the pump cover. In looking at the impeller it appeared to be damaged so I removed it. In fact, 2 fins were gone and 2 more were split. With the oil cooler out I was able to pass my trombone slide brush down through the hose and was able to pull out the 2 missing pieces. In viewing my records the impeller was last changed in 2018 with about 750 hours on it. I thought I had replaced it since then but if I did I didn’t note it in my log.

The 2 missing fins on the impeller that I saw in this picture that told me it needed to be changed. The only way I can see in there is with a camera or mirror.
 

Next, I removed the hose to the muffler with the mixing elbow and cleaned them thoroughly with degreaser and a wire brush until water running out ran clean. I also used the opportunity to clean the engine well from the dirt that accumulates around an engine. I also used a wire brush to clean loose debris from the inside of the exhaust manifold and clean it with a degreaser.

Then I began reassembly of the oil cooler. Since I didn’t remove the hoses from the end caps they remained in place. With the fixed oil lines framing the oil cooler location, I inserted the core into the oil cooler housing and then situated it into its spot. I tried securing the housing with its bolts but then I couldn’t get access to the inside end of the core. I inserted the O ring and put a bead of red silicone sealant around the inside end cap and across the center of the core where a rubber gasket should be. I pushed that into the end cap and secured the 3 bolts (1 mounting bolt and 2 end cap bolts) on the inside end. Next, I attached the 2 mounting bolts on the outside end fully securing the oil cooler housing. The core was not fully in the inside end cap. I attempted to budge it in with light taps from a rubber mallet but it didn’t budge so I put the outside end cap in place and tightened it all the way which pushed the core into correct position. I let the assembly set overnight so the gaskets on the other end could fully cure. Then I removed the outside end again and inserted the O ring and used red gasket material around the perimeter of that end cap and the gap in the middle and resecured the end cap.

A view under the exhaust manifold at the hose and clamp (circled) connecting to the lower inside of the oil cooler. The end of the oil cooler is a few inches up from that. I didn't remove it because I thought it would be too difficult to maneuver the complete oil cooler back in to get that hose connected. Possibly with a second set of hands maneuvering it in from underneath.
 

With the core mounted in place I tried to reattach the oil supply lines having received my parts. Reattaching the side oil pipe was frustrating. The pipe didn’t line up exactly with the opening. After many unsuccessful attempts I loosened the 2 mounting bolts on the outside end and removed the inside mounting bolt completely. When trying to work this I continued dropping the copper gaskets because I needed to lift and pull the oil cooler with one hand and try to feed the bolt in with another. I was doing this by laying on the floor by the starboard access door. Finally I had my wife come around to the inside of the engine and lift up the cooler and keeping one hand around the inner gasket and working the screw with the other I was finally able to get that bolt in. After getting the oil bolt in I resecured all of the mounting bolts. Then I firmly tightened the oil line bolt with a medium-sized adjustable wrench.

I then reinstalled the oil line to the top of the oil cooler which was much easier but still took effort to line up for the bolt to feed into the housing. I secured that with the 27mm socket. I had ordered new copper gaskets and replaced them on both oil lines. 

Parts drawing showing the mounting of the Oil Cooler.
 

Next I replaced the small hose that runs from the oil cooler to the heat exchanger with a new piece tightening the clamps on both ends.

Having received the parts I used the machine shop in the marina to attach the mounting studs for the mixing elbow, the elbow and stop cock on the new turbo so it was ready to install.

There is a metal gasket that fits between the exhaust manifold and the turbo that will be there when the turbo is removed. I inserted the metal gasket onto the exhaust manifold studs. I had cleaned the gasket well before reusing it but it was in good condition. Then I sat the new turbo onto the studs and began the task of attaching the washers and nuts onto the 4 studs. I was able to start them with my fingers and then use a 13 mm flat wrench to tighten. It requires different positions for each nut. I found it easier to work from standing in the engine bay. I put tef gel on the studs to prevent corrosion and seizing. 

Parts drawing showing the disassembled oil cooler. The O rings on the inside end not completely mating is what caused the leak on initial reassembly.
 

Next task was to connect the bottom oil line. Before I mounted the turbo I replaced the O ring in the oil line. I first tried to install the outside bolt but like the other oil connections this required great effort to properly align the holes in order to start the bolt. Once I was able to do that the bolt went in fairly easily. Then I looked to reinstall the back bolt. But, in examining the site I found the new O ring in pieces so I had to remove the turbo. In my kit of O rings I found one that fit it perfectly so I remounted the turbo on the studs and redid the front bolt on the oil line. For the rear bolt I redid the way I took it off. I put the bolt into the socket connected to a 3” extension and taped it in with a small piece of aluminum tape and turned it with my fingers to get it started. It actually didn’t take very long to get it started and then I removed the tape and put the socket extension onto the flex head and driver and secured the bolt.

Then I simply reversed all the other steps to reinstall the other hardware. As noted above in reinstalling the “pipe” the end was decayed so I replaced that with a new high-grade fuel line. I have the OEM part that I will install next time I change coolant. I also inserted a new gasket into the connection with the mixing elbow and secured it with red engine sealant. 

Looking into the Air Intake manifold with the oil pipe just below it.
 

After finishing all the reconnections I added oil to compensate for what came out of the oil cooler and added coolant. Since I used some red engine sealant on the mixing elbow I let that set for a day before starting the engine to check for leaks.

When I tried to start the engine the first time the engine alarm sounded when I turned on the key but nothing happened when I hit the start button. After investigation it turned out one of the connections had gotten loose during the install and we quickly fixed that. That fixed, the engine started but I immediately found a leak at the top of the inside end cap on the oil cooler. I had failed to seal it well enough.  So the oil cooler would have to be removed.

Looking into the Exhaust manifold. The bolts and studs there were likely to be exposed to salt water I put Tef Gel on to limit corrosion.

Now the challenge was taking out the oil cooler without removing the turbo.

I started by removing the air duct intake by removing the 4 mounting bolts and the loosening the clamp at the turbo charger.

After study I determined that the end bolts of the inside end cap could be removed. The bolt on the lower end of the cap I removed with a 12mm socket on the end of a 6’ extension and a ¼” socket driver.  Probably could also use a 3/8 extension and driver. The top bolt was removed with a 12mm box wrench. I decided not to remove the inside end cap with the cooler because the raw water supply hose mounts on the inside bottom with a clamp on the end cap and one on the pipe from the water pump. I decided again that it would be too difficult to replace the hose onto the pipe if it were removed. 

View with the turbo and oil cooler out. You can see the O ring on the oil pipe that got messed up on re installation of the turbo. You can also see the bracket that requires skills to remove the inside bolt.
 

Removing the bolts on the oil attachments was straightforward and the mounting bolts as described above. It is necessary to remove the top bolt from the outside end cap to remove the oil line mounting bracket. I then reinstalled that bolt to keep the outside end fully secured.

After removing all the bolts the oil cooler was removed. It requires manipulation of the cooler because of the short distance between the end to the wall and the standing oil pipes. 

In the top right of the photo is the aft outside mounting bolt for the oil cooler. As you can see the oil pipe goes up about an inch in front of it. It can be accessed from the rear of the engine with a box wrench. I don't believe my ratchet worked on it and there is only about an inch to move the wrench at a time. When the bolt gets nearly out it is against the oil pipe.
 

On removal I saw why the end leaked because there was too little caulking and the O ring was too thin even though it is the identified part for the position. I left the other end on as it wasn’t leaking.

Forward outside bottom of the oil cooler end. The bolt on the left is the end cover and the one on the right is the mounting bolt.
 

I applied red engine sealant around the O-ring enough to secure the O-ring and block the outflow of oil from the cylinder. Then I took the cooler and tried several manipulations to get the cooler into the slot and through the standing oil pipes. I found that turning it upside down and getting it in place and then turning it rightside up. Of course doing that more oil came out. I should have anticipated that there was still oil left in the core and blocked it with tape or rags.

Once I had the cooler in position I put the outside mounting bolts on loosely. I also secured the inside end cap fully tightening those two bolts to squeeze the sealant into place.

A view of the top outside end of the oil cooler. The hoses to the transmission, the top end cap bolt and the bracket for the top oil pipe. It's necessary to remove this top bolt. Loosen the pivot bracket and turn up the bracket and I reinserted the end bolt and tightened it before removing the oil cooler the second time.
 

I then tried to attach the oil supply line that proved a bridge too far. Or, a hole too far. I loosened the mounting bolt on the inside end taking care not to back it out too far that it would come out because with the turbo in it’s almost impossible to reach that bolt by hand. Loosening the bolt helped to allow the cooler to move very close to a good position but it still did not align. After attempting several times to manipulate the oil supply line with one hand and turning the bolt with the other I decided to ask the lead worker in the marina for help.

When he came over the next day he attempted unsuccessfully to get the bolt in with my help. Then he decided to tie a small line around the pipe. He was able to get the copper gasket on by pulling cooler away from the pipe and putting the gasket on the bolt and then pinned it between the cooler body and the pipe. He stood in the engine well pulling the pipe up and over and I laid on the floor of the galley and got the bolt right in. This proved to be the easiest way unless you remove the mounting bolt and deal with trying to reinstall it. This step is identified as the hardest task in the entire process. With another hand it became easy. 

The inside end cap for the oil cooler. The lower bolt is for the end cap. The upper bolt is the mounting bolt. With the turbo off and the connector hose removed it was easy to access this. But with the turbo on it's difficult to move the connector hose and to turn the mounting bolt a wrench will move about an inch at the outside end. I believe I was able to get a rachet wrench on it to make the small movements go faster.
 

With the oil supply line connected I then tightened all the mounting bolts. Then I reattached the connection from the oil cooler to the turbo. Then I reattached the bracket to the outside end cap and tightened the pivot bolt.

At that point the oil cooler was fully reinstalled.

The next morning I checked the fluids and started and ran the engine with no leaks. The exhaust was clean water coming out with no oil or smoke, I ran the engine until hot and for awhile after and no leaks. The following day I ran the engine again to ensure that all fluids were at operating condition and ready for a sea trial.

On sea trial, the engine performed as it had been. The new turbo didn’t make a difference. On to continue the search for other possible causes.

 

All back together again except the thermal jacket on the mixing elbow.