Leaking Heat Exchanger Gasket - Maybe?

[colb218]

Hello All-

I have a Yanmar 3HM35F and today I planned to change the fresh water. I pulled out about 3/4 of a gallon of the orange coolant. As this was my first time changing the coolant I spent some time looking around and noticed that I had some rust forming on a particular spot on the engine. I had seen this before and planned to address it, but as I was looking at how to get access to refill the coolant I looked closer and it appears that the heat exachanger might be leaking raw water from the forward part of the exchanger. So like all boat projects my 2 hour fresh water change has turned into a larger project.

At this point I believe I will need to take off all hoses(raw and fresh) and then remove the heat exchanger. Once I get it home I should be able to get the cap off and replace the gasket.

Before I dive to far into this and assume I am fixing the problem, does what I am seeing and my remedy seem like the most likely culprit? Do heat exchanger gaskets leak? Or is this going to be an even larger issue? It is hard to get images, but I have attached a couple

 

[jssailem]

Sure looks plausible from what you describe.
If a leak can happen it will. It may be just a hose that has leaked and not a hole in the heat exchanger. Taking off the heat exchanger is a practical approach. I did that with mine. I took it to a radiator shop to get cleaned (boiled out), and then pressure tested. I also provided them a zinc anode to install. When I looked inside I found that the anode was gone. You will want to have new gaskets for the ends so that they can put the heat exchanger back together for pressure testing.

Cost me $65 and took 6 days to get in to their work schedule.

I got my zinc from BoatZincs.com (978-841-9978) - America's Superstore for Marine Anodes. But I suspect Fisheries and Harbor Marine will have them.

 

[colb218]

Sure looks plausible from what you describe.
If a leak can happen it will. It may be just a hose that has leaked and not a hole in the heat exchanger. Taking off the heat exchanger is a practical approach. I did that with mine. I took it to a radiator shop to get cleaned (boiled out), and then pressure tested. I also provided them a zinc anode to install. When I looked inside I found that the anode was gone. You will want to have new gaskets for the ends so that they can put the heat exchanger back together for pressure testing.

Cost me $65 and took 6 days to get in to their work schedule.

I got my zinc from BoatZincs.com (978-841-9978) - America's Superstore for Marine Anodes. But I suspect Fisheries and Harbor Marine will have them.

Good news! Got the heat exchanger off today!

I think I will be replacing the fuel line that goes from the yanmar fuel filter to what I think is the high pressure pump as the one I have on there is a solid line and rusted.

Pretty sure the previous owner had this on the to do list as I appear to have all parts necessary to move forward with the exception of the exhaust gasket. I even have a brand new radiator cap and brand new raw water and coolant hoses to install!

Any suggestions for a radiator and hydraulic shop around Everett? Next up will be to assess the rust situation and get it painted again.

 

[jssailem]

For fuel lines and hydraulic hoses, I’ve used North Sound Hose and Fittings, now called ARG Industrial.

ARG Industrial (Formerly North Sound Hose & Fittings Inc.) · 4.5★(34) · Hose supplier

3520 Paine Ave, Everett, WA 98201

maps.app.goo.gl

You called the hose a “solid fuel line”. Is this a high pressure line? You may need to source this item from Yanmar.

 

[colb218]

I do not believe it is high pressure. It leads from the yanmar fuel filter(not my racor) to what I think is the high pressure pump. It is a solid line but looking online it appears that the fittings should be able to be removed and then added to a more modern line. The videos I watched and the posts I have seen all have a 'flexible hose' rather than the rigged bent to fit pipe.

 

[jssailem]

Low pressure lines do not require rigid pipe. High pressure lines do. On some engines they use rigid pipe because they have it.
Do the fittings have a brass compression sleeve on the pipe under the thread nut?

Will look something like this…

Compression Sleeve for 1/8" Copper Tube OD
These should be replaced every time the fitting is removed to prevent leaks.

 

[colb218]

Managed to pick up the heat exchanger gaskets today after dropping it off at Greenwood Radiator on Tuesday. They have already boiled it off and tested the cylinder, but needed my gaskets to test the rest. It looks so shiny now!

Was able to confirm that the fuel line is low pressure so will be heading to the boat to remove that so that I can get a new one made. Hoping to treat the rust when I pull the fuel line off.

Only gasket I am struggling to source locally is the exhaust manifold gasket, but it is rainy and gross out so I have some time to wait for shipping.

 

[colb218]

Sorry to keep bumping this, just trying to determine how far down the a rabbit hole I want to go. I received the heat exchanger back and it looks fantastic! Anyone looking to get work done in the Seattle area, Ron at Greenwood Radiator was great to work with!

Of course now that I have it back and see how clean the exhaust ports look compared to the ones on the boat... how much effort should I put into removing carbon build up? Ron mentioned that he used everything from brake cleaner to acid to get it cleaned up to the point it is now.

The actual exhaust ports are not something I am not super comfortable with. Would a shop vac and dremel be a decent tool set to work on this? According to the logs, the Exhaust Elbow was replaced Jan of 21 so it is only 3 years old at this point so I doubt that will need any service.

I mentioned in another thread how I was not running my engine up to the proper RPM range and while we haven't put a ton of hours on the engine in our 2+ years of ownership it has seen some time.