Cleaning heat exchanger

Velera · **Joined:** 29 Dec 2006 09:38 **Posts:** 656

Well it is definitely a W50. It shows some care and maintenance. From the picture, the salt side (lower half) of your heat exchanger looks very funky and needs to be cleaned. It is kind of hard to remove the nuts from the studs that hold the heat exhanger in place on the exhaust manifold, but it is possible if you are patient. I would put a cloth under the nuts as you remove them as they have a tendency to fall into the bilge when they come off.
I would not expect much of anything to be in the muffler it does not need routine maintenance. But you need to inspect the exhaust elbow and pipe. You can replace this easily—no need to order a part-I think black iron pipe is preferred, but anything will work—you might wrap it in muffler tape to keep the heat down in the engine space and prevent burning yourself—if there is anything occluding the elbow or pipe, you should just replace it—you will find the black stuff is impossible to remove.
Ray Durkee

Velera · **Joined:** 29 Dec 2006 09:38 **Posts:** 656

Photographs are tough to diagnose from, but it would seem that the sea water injection site might be a bit crudded up. You need to get it all apart. You need a big pipe wrench. The first time I did it, I was worried about cracking the expansion tank, but it was OK I think I had to take an extension on a large pipe wrench. Probably soaked the joints in some penetrating oil overnight before putting a lot of power in there. I take back the idea of rerouting the oil cooler for now. I do not think this is the standard way these came from Tartan, but it might have been an improvement in saving the oil coolers from salting up. I would change that only if all the cleaning of everything does not result in cooling it down a bit. Do you have good total flow out the exhaust?
Ray Durkee

felizcortez · **Joined:** 25 Apr 2016 10:25 **Posts:** 185

Yes, I believe I have good flow out of the exhaust. It sprays out with more force when the engine is running at a higher RPM.

For the elbow if I need to replace that, I just have a local welder put another nozzle into it? Or are you talking about only replacing the straight pipe section? I need to get a cheater bar or a larger pipe wrench. I put some penetrating oil on it yesterday while I was tryign to muscle it off and also heated it up with a small butane torch, but neither of those were able to unstick it. I removed the muffler becuase I couldn't get the hose off the end of the elbow, but I could separate it from the muffler. That way if i could get it to turn it wouldn't be inhibited by the attachment point at the muffler.

Are you saying the heat exchanger can be removed while the exhaust manifold/coolant reservoir is still on the engine? I thought that had to get removed in order to remove the heat exchanger.

I did a rudimentary check on the gauge to see if it functioned properly at full scale - removing the wire from the sender caused it to read zero and grounding the wire caused it to read full scale.

I measured the resistance of the temperature sender without the wire on with the engine cold at 77F and got a reading of 750 ohms. Not sure if this correct or not. When the engine was warmer yesterday it was reading in the 300's but the engine had cooled down since I had run it. Does anyone know what hte proper specifications for the sending unit are? THe reason I'm concerned here is because of the IR thermometer measurements I took on the thermostat housing that don't seem to agree with the gauge.

Velera · **Joined:** 29 Dec 2006 09:38 **Posts:** 656

I admit I do not recall if you have to remove the expansion tank to get at the heat exchanger. I seem to recall that I had to just because there was no room to get it any other way, but I note some different things on your W50 (like where is the thermostat??). What I do recall is that, like many things, taking this bugger apart the first time was a miserable job, but that it was a piece of cake after the first time. Maybe you can get away with getting the heat exchanger off the bottom of the expansion tank and save some time.
I would recommend replacing the exhaust pipe, the elbow and the whole thing—but your hoses and clamps look new. Pipe is cheap. You could have an exhaust elbow fabricated for very cheap there just take to old parts to someone and make sure the water is not shot back into the exhaust manifold—needs to spray down stream. If it has not been previously replaced and if the engine has 1500 hours or so or more—it will be crudded up with carbon and it will not be possible to remove the gunk with physical effort or chemicals. It is a maintenance item that most folks forget.
My personal belief is that most recreational marine diesels die of carbon build up (from being used at slow speeds and short intervals) that kills the exhaust valves eventually through back pressure. Diesel manufacturers like Yanmar will not warranty their 3 cylinder engines without a 3” exhaust hose—the stock Tartan W50 came with a 1 and 7/8 ths hose 12 ft to the stern.
Keep us in the loop.
Ray Durkee

Mike · **Joined:** 09 Jul 2008 12:51 **Posts:** 251

Before removing the heat exch to clean it may I suggest close looping the coolant system, attached to a pump and run barnacle buster through it for 10-24 hours. I do this once a year and clean the heat exch like new. So,,, disconnect the hose going to the exhaust elbow, attach that to the pump,,, disconnect the hose at the fresh water pump and put that in the bucket with the barnacle buster. You'll want to have the flow of the water going backwards to back flush everything. BE SURE TO REMOVE YOUR ZINCS...barnacle buster will eat them up.

If you really want to remove the heat exchanger, it's really a piece of cake.
The manifold will come off with it. The top screws are the only thing holding it on. The two end screw need to be completely removed. The screws in the middle just need to be loosened... those screws are nothing more than "support" screws to "hang" the manifold when you install it and remove it. It will "lift" right off the side of the engine. Be careful not to screw up the manifold gasket when you do this so the more play in those middle screws is a good thing. Disconnect the hoses first of course... It can be done in about 30-40 minutes.

As for the exhaust elbow... this can cause back pressure AND be the main cause of many a engine heating up. I purchased an alloy model because I was tired of dealing with RUST. My local marina custom made the hose attachment to the manifold.

Cheers...

felizcortez · **Joined:** 25 Apr 2016 10:25 **Posts:** 185

So after further debug, I ran the engine at high load while tied up to the dock. I shot the thermostat housing with an IR thermometer and it read between 180F and 185F depending on whether the thermostat was opening or closing. The gauge is reading about 200F. My belief is it was the gauge. I had a mechanic come take a look at it yesterday to get a second opinion. He also brought an IR temp gun down and performed the same check on the thermostat housing. He got roughly the same readings (within about 3 degrees of mine) which is within the accuracy level of the temp guns. We ran the engine for over an hour and he agreed that the gauge was running hot by about 15 to 20 degrees, but the engine was operating as it should.

His comment - "Your engine is running perfectly, either the gauge or the sender is wrong"

I asked about the oil cooler plumbed into the fresh water circuit and he wasn't concerned about it.

The mechanic had a spare USA style gauge, so I alligator clipped it to power, ground, and the sending unit output and it read 180F to slightly over 180F which matched the readings on the IR gun and are within tolerance on the thermostat. So the gauge I have on the boat is reading hotter than it should. Not absolutely critical to fix immediately since we know it's running hot, but I ordered a new gauge and sending unit. My parents are bringing it down when they visit next week and I'll install it when it arrives.

I learned a ton about the cooling system and also feel good about getting to the same diagnosis as the mechanic. I wanted to get a second opinion since this could have been expensive had we actually been overheating. Appreciate everyone's help on this one as the responses were extremely helpful. Now off to the islands to explore some more. Very Happy

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Cleaning heat exchanger

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