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 Post subject: Re: Cleaning heat exchanger
PostPosted: 30 Apr 2019 16:39 
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Joined: 25 Apr 2016 10:25
Posts: 91
We are anchored at Ensenada De Los Muertos and I had some time to pull apart the raw water circuit. I went through each hose and also cleaned out the strainer. I couldn't find any obvious blockages in any of the hoses or in the heat exchanger. I changed out the zinc while I was at it as well.

The one surprising thing was that the oil cooler is plumbed into the fresh water circuit. I went to take the hose off the input based on the posts that this is the likely source of the problem and antifreeze came out. I verified that this was hooked up this way as the output of the oil cooler goes to the hot water tank.

I also made sure that the rubber cap was on correctly. It is quite groved so it would be hard to get this wrong.

I will post a picture of the heat exchanger after I get some reliable internet. Posting this from a sat phone.


 
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 Post subject: Re: Cleaning heat exchanger
PostPosted: 30 Apr 2019 18:57 
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Joined: 25 Apr 2016 10:25
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Pics attached to the message. If need more I will upload again.


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 Post subject: Re: Cleaning heat exchanger
PostPosted: 30 Apr 2019 19:15 
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Joined: 25 Apr 2016 10:25
Posts: 91
Here are some more pictures that show more detail of the oil cooler and the other hoses in the system.


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 Post subject: Re: Cleaning heat exchanger
PostPosted: 30 Apr 2019 22:14 
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Joined: 29 Dec 2006 09:38
Posts: 538
OK. I agree that, unless your engine is different from my W50, the oil cooler should not be part of the freshwater coolant circuit. I am trying to figure out how that could happen or be thought to work. Since there are so many potential points of obstruction in this cooling system and (it is tough to see in photos) it is difficult to suggest where the problem is, but I do not like the look of your main exchanger cooler tubes. The lower set of tubes (which is where the initial salt water is first exposed to the hottest coolant) looks a bit crusty. The upper ones look OK in the picture-but you understand the flow is sequential through both—so if either is clogged you are in trouble.
Removing the coolers is a bit of a chore but is doable and I would not let this stand in the way of doing the right thing at some point—cleaning it at a radiator shop (and getting it pressure tested) if it has been 1000 or 2000 hours since it was blown out. I replaced my W50 engine 10 years ago with a Yanmar, so my recollections of working on the W50 are a bit hazy, but I had the coolers out at least three times to have them cleaned out in 4000 hours I had it—twice it was essential as there was a heating problem related to them. The first time I took it apart, it was a bitch, but it got easier subsequently. The hardest part is the manifold nuts that are in a very cramped spot, but a crows foot open end wrench is a big help—but I have done it with a regular wrench and some tape to catch the nuts and set them (if you take it off you will understand what I mean). I think you can reuse the manifold gasket at least once—they are not generally crushed or glued on and the torques are “two finger” and not critical—at least once or put some RTU gasket maker on it (by the way, I found the manifold loose when I first did the job). Yes you will have to replace some coolant if you take this apart, but that seems a small price to pay if these are the problem. I realize dumping a caustic chemical in there could maybe do the same thing (seems risky to me—the insides are copper and react to some acids), or maybe flushing it backwards with a garden hose might help, but sooner or later you have the choice of doing this right or running a significant risk of overheating when you do not expect it. If you are doing ocean passages, I think this is a regular critical maintenance item at some interval.
You have a different and less fussy cap on your main cooler than some of the W50’s, so that is probably not the problem. Some of them have a cap with a deep groove the divider must be exactly position in or overheating is inevitable (don’t ask what I went through to learn this).
One of the reasons I do not like these “marinized” tractor engines is the fact that the marine salt/fresh cooling systems are generally cobbled together with a lot of hoses, connections, dissimilar metals in salt and heat, and a lot of potential points of failure. You can manage it, but it takes active owner involvement in maintenance or there will inevitably be problems. You cannot wait till you have a problem because it will happen at the wrong time. I have stories about how I learned this—it once was near disaster, but I will save them for a different venue.
I am telling you this, because you appear to be someone out there actually doing ocean passages and probably depending on your diesel in some out of the way places where failure could be a problem. Marina folks and weekenders can probably just limp to the slip or call the tow boat when they have the predictable overheating that will occur without maintenance of this system.
Ray Durkee


 
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 Post subject: Re: Cleaning heat exchanger
PostPosted: 30 Apr 2019 23:02 
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Joined: 25 Apr 2016 10:25
Posts: 91
On the oil cooler plumbed in to the coolant, I would think this would cause more resistance to flow and potentially cause a problem. I was also reading that Raritan water heaters have more resistance to flow than other brands so a coupling is recommended to allow a bypass of the actual heater so restriction to flow is reduced. I didn't see this type of coupling on the water heater either.

I would need to figure out where to replumb the fresh water circuit if I put the oil cooler back in the raw water circuit. Where do most people put the hot water heater output? I had assumed the cooling system was hooked up correctly, but I do not have history. I don't think the previous owners did any major cruising so if it was a dock queen then they likely would have never experienced problems. Does anyone have pics of how their water heater is plumbed into the system?

On the heat exchanger cleaning, I am going to have to get to La Paz to be able to make any sort of repairs. We are planning on staying in LaPaz for awhile so it should enable us to get this fixed I do not want to leave this as it can be a problem I don't want to deal with in the Sea of Cortez. I believe I have a spare manifold gasket but I don't think I have the heat exchanger ones. Will need to check on availability in La Paz.

I am running about 5 to 10 degrees hot depending on how high of an RPM we run the motor. However it is stable at that temp for now and I am only a few days from la Paz so I think we should be okay until we get there.


 
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 Post subject: Re: Cleaning heat exchanger
PostPosted: 01 May 2019 10:23 
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Joined: 29 Dec 2006 09:38
Posts: 538
Do you have a W50? I can help you with the oil cooler routing if that is the model—if not, if you had a wide angle shot from the top it would help figure out what is going on—or a hand drawn schematic of how things are currently routed. Are you sure the temp gauge is accurate? Are you sure the thermostat is working right (if it is a W50 the thermostat needs that eighth inch hole in the rim to register accurately) Have you checked the exhaust elbow itself?—I mean actually taken it off and looked through it? Looks like it is galvanized pipe and that stuff collects salt and soot like crazy. Mine was 2/3 occluded at one point. You should be able to get the help you need in La Paz and you are right to do it there if you are going into the Sea of Cortez where you will be entirely on your own.
I had a bypass to the water heater, but it did not seem to matter much in long term motoring—-if the valve is between the hoses it is there for controlling the flow through the heater (to keep the water heater from getting super hot scalding water) , not controlling the freshwater temp of the engine. Air in the system can make temps appear higher than they are as the thermostat is generally at the highest point in the system in most engines. But I think you knew all that.
If you get this all inspected and cleaned out in La Paz you should be comfortable for the next 1000 hours. The problems with diesel engines are rarely with anything other than fuel supply or exhaust/coolant issues. And exhaust/coolant are the bugaboos with most as a lot of them are not well designed—as you are discovering.
Ray Durkee


 
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 Post subject: Re: Cleaning heat exchanger
PostPosted: 01 May 2019 10:54 
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Joined: 25 Apr 2016 10:25
Posts: 91
Can't post a pic due to lack of internet. Yes I have a W50 with the jabsco raw water pump.

The raw water circuit enters the through hull goes to the strainer then the jabsco pump. From there the raw water goes to the input of the heat exchanger. The output of the heat exchanger goes to a vented loop then to the exhaust elbow.

For the coolant the fresh water exists the main heat exchanger then is hooked up to the oil cooler. The output of the oil cooler then goes to the hot water heater then that returns to the engine.

I will try to take a video or post a pic when I get some internet. We are ok the move right now and we are still running a little hot.

I haven't pulled off the exhaust elbow to look yet. Do I just use a pipe wrench and muscle it off? Any tips or do I need to use a sealant to it back together?

To bleed any air do I just open the banjo fitting at the thermostat? I did change the water pump a few weeks ago so I may have introduced some when I refilled it.


 
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 Post subject: Re: Cleaning heat exchanger
PostPosted: 01 May 2019 11:15 
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Joined: 25 Apr 2016 10:25
Posts: 91
I also just used a IR thermometer on the thermostat housing while the engine has been running for a few hours. The temperature of the housing was about 178 degrees. I figure this should be about the same temperature as the actual coolant itself after running for a few hours. Give or take a few degrees.


 
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 Post subject: Re: Cleaning heat exchanger
PostPosted: 01 May 2019 12:12 
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Joined: 25 Apr 2016 10:25
Posts: 91
A few data points

The 178 degrees was at 2000rpm
When I increased to 2300 rpm the temperature rose to 186 at the housing. The gauge is reading I believe 200ish at that point. Hard to tell because the scale isn't linear.


 
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 Post subject: Re: Cleaning heat exchanger
PostPosted: 02 May 2019 20:46 
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Joined: 29 Dec 2006 09:38
Posts: 538
The oil cooler should not have freshwater coolant in it. It should be connected to the seawater output of the main heat exchanger. The oil cooler seawater output then goes to the exhaust elbow injection point. There is a schematic on line that shows this. Seems like someone replumbed your system and did not get it right.
You can take the hot water hose run off the system anywhere as long as you take it out from after the thermostat and dump it back in before the thermostat. I think the orginal routing was off the thermostat to the water neater than back to the fresh coolant side of the main heat exchanger. You can bleed the system at the thermostat because this is the highest part of the sytem. After you take it apart, it is going to take several times to get all the air out. Helps if you get all the air out of the coolant lines to the hot water heater before you hook them up as air bubbles seem to collect in it.
Hope this helps. Learning this coolant system is a must for anyone doing any serious cruising with a W50 and once you get it fixed up and understand it, if you keep clean fuel in and change the oil regularly, the engine should be trouble free for a very long time.
Ray Durkee
T37 #373


 
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