Coolant Leak Troubleshooting

[assfortress]

My Universal M-40 has been losing coolant, and I'd like some help determining the issue. Here are the symptoms:

• The last two times I took my boat out I started with all fluids at proper levels. I motored for ~30-45 minutes, constantly monitoring the expansion tank which increased a small amount as I would expect. shut the engine down and sailed for ~1-3 hours. Before restarting the engine I took a look at the expansion tank - right at the same level as before. Motor for another ~30 minutes-1 hour keeping a close eye on the expansion tank, coolant stays right at the same level. When I shut down the engine the coolant stays until the engine has cooled down. With in a few hours I open the fill cap on the actual engine and there is coolant. In the morning the coolant is gone.
  
  
• Next time I operate the engine: I fill the coolant. When I start the engine it looks like there is coolant coming out with the exhaust water, it almost looks like mildly soapy water. (The first time this happened I didn't know what it was so I shut the engine down, started it again in ~5 minutes and the exhaust water was pure water, no soapy look to it). Exhaust water keeps the clean water look the entire time I operate the engine.
  
  
• My oil does not look cloudy - leading me to believe its not a head gasket.
  
  
• There is no coolant below the engine in the bilge.
  
  
• My heat exchanger is pretty much the lowest point at the back of the engine. My hypothesis is that there maybe an internal leak between the raw and fresh water circuits.

  • If there was a leak in the heat exchanger would the raw water be pressurizing the coolant circuit? That could explain why I could operate the engine without overheating and the expansion staying full?
    
  • Could that also explain how the coolant would just leak (by gravity) into the exhaust when the engine is off?

I'm brand new to troubleshooting engine so if my wild guesses as to the problem are totally off base please feel free to let me know the error in my thought process.

Thanks for reading.

Matt.

[MarkSF]

This engine has the exhaust manifold jacketed by the freshwater coolant tank. I wonder if that could be the leak path? Straight from the tank into the exhaust manifold?

[Unicorn Dreams]

Welcome Aboard Cruisers Forum

[sneuman]

I think Mark might be right. I'm no engine expert, but have worked through a few problems myself. The "mixing elbow" that comes off the exhaust manifold could be corroded through (not uncommon), allowing the coolant to pass from the jacket into the raw water exhaust. The elbow may need to be replaced.

[GordMay]

Greetings and welcome aboard the CF, Matt.

[assfortress]

Thanks for the warm welcome!

So is there some weak link that makes the elbow more suspect to have a leak as opposed to right in the main coolant tank or in the heat exchanger?

Any thoughts on how to isolate the leak and confirm it is the mixing elbow? If I take that piece off would an engine shop be able to pressure test it? Thanks again.

Matt.

[DeepFrz]

I have never seen a mixing elbow that was cooled by the engine coolant. Mixing elbows are cooled by the salt water discharge from the heat exchanger, to the best of my knowledge.

[CaptainDana]

Deep fez is right. The elbow is where hot raw water enters the exhaust stream. If coolant is finding it's way into the exhaust stream, it's happening in the exhaust manifold or in the heat exchanger. Based on your narrative, I'd test the heat exchanger.

Most coolant leaks are from hoses/pumps but there's lots of telltale steam/coolant in the engine compartment when that happens.

Good Luck!

[Chief Engineer]

If you have an auto parts store close by....the big chains loan tools. get a radiator pressure tester. The cap should fit on your Tank (not the overflow bottle) pressurize it to the rating on the cap

[sneuman]

Originally Posted by DeepFrz

I have never seen a mixing elbow that was cooled by the engine coolant. Mixing elbows are cooled by the salt water discharge from the heat exchanger, to the best of my knowledge.

this is correct. I am wrong. Now, I did preface the earlier by saying I don't know much about engines.

[assfortress]

So if my coolant is leaking into the heat exchanger is it likely that salt water is also making its way into the coolant circuit? I’m just wondering if I should run my engine weekly to exercise it, and I’d also like to move my boat to another slip, prior to fixing the issue? I’m probably 2 months from being able to fund this project. Like I said, when it does run its not overheating. I just don’t want to damage the engine by not exercising it, and I don’t want to damage it by running it. What are your thought?

[SV Demeter]

Originally Posted by assfortress

So if my coolant is leaking into the heat exchanger is it likely that salt water is also making its way into the coolant circuit? I’m just wondering if I should run my engine weekly to exercise it, and I’d also like to move my boat to another slip, prior to fixing the issue? I’m probably 2 months from being able to fund this project. Like I said, when it does run its not overheating. I just don’t want to damage the engine by not exercising it, and I don’t want to damage it by running it. What are your thought?

I had an Ericson 38 for a number of years same engine. Not sure what year you have but I had an '86. If you go in the aft cabin you can remove the top of a shelf that is directly above the heat exchanger on that motor. The heat exchanger (3" diameter cylinder about 15" long) is held onto a bracket with 2 hose clamps. Remove the 4 hoses ( raw water in/out, freshwater in/out) and the 2 clamps and out comes the heat exchanger( might want to drain the cooling system first .Take heat exchanger to radiator shop for testing or remove end caps and see for yourself.

I replaced mine as it was pretty corroded. Trouble is there is a zinc in that heat exchanger that is a bitch to get to on the ericson so most never change it. Zinc erodes then electrolosis takes over.

Good luck. PM me if I can be of any other Ericson 38 help. Ive been all over that boat.

[assfortress]

Thanks Demeter. I'm hoping to tackle the removal next weekend, or the next, depending on the availability of my more mechanically inclined friend. In the mean time am I do any damage firing up the engine if the temperature stays low?

I'm still wondering if its possible that my coolant circuit is getting contaminated with salt water (not exactly salt water here on the Columbia River, but plenty dirty) when I run the engine in this state?

Thanks again everybody.

[SV Demeter]

I dont think you will do lasting damage if the temps stay under control but if you have salt or raw water running in your freshwater cooling circuit you are going to want to make sure you flush the system well once you fix the heat exchanger. One other thing to consider is on the M-40 most people have gone to a higher capacity heat exchanger due to cooling problems. The original heat exhanger for that engine was about 2 1/2" in diameter I believe. The upgraded one is 3" and I think a little longer. If you end up having to replace the heat exchanger make sure to go with the bigger one. When I had my Ericson 38 I used a place call Torrenson Marine I belive in Michigan for parts.

try here: Torresen Marine

and for the heat exchanger try here:

Torresen Marine Exchanger Group-New&quant_position=&catalog=200146&printparts=2001 46&printservice=200154&printoperators=200157&comme nt1=

they are not cheap and you may be able to do better looking online...