Losing Coolant, Found it on Seawater Side


secondtimearound

secondtimearound

New member
I recently noticed that the coolant level in the reservoir was very low, so I topped it off. We had run the boat on the weekend and it had gotten cold that week, so I thought maybe the change in temperature had affected it. I'm diligent with checking all fluid levels and all were fine before running the boat. This weekend I was winterizing the freshwater system, so I decided to pump the water out of the block using the supplied hand pump. I found coolant coming out of the port engine drains. The engine oil is clean and the coolant reservoir was slightly lower. Maybe a heat exchanger issue? Has anyone had a similar experience? Thanks in advance for your input.
 
Needs some clarification
You have a closed cooling system (mentioned coolant level in the reservoir and heat exchanger) but ..... you then said

was winterizing the freshwater system, so I decided to pump the water out of the block using the supplied hand pump. I found coolant coming out of the port engine drains.
Click to expand...

It doesn't require draining the engine block to winterize the motor, only the raw water side of heat exchanger and hoses

In a closed cooling system there is antifreeze coolant in the engine block, so coolant should drain out of the block if the drain plugs are opened. So why was the engine block drained?
 
AllDodge said:
Needs some clarification
You have a closed cooling system (mentioned coolant level in the reservoir and heat exchanger) but ..... you then said



It doesn't require draining the engine block to winterize the motor, only the raw water side of heat exchanger and hoses

In a closed cooling system there is antifreeze coolant in the engine block, so coolant should drain out of the block if the drain plugs are opened. So why was the engine block drained?
Click to expand...
Sorry sometimes I give unnecessary details about what I was working on at the time. It is a closed cooling system. I was using the pump for the water drain system to drain the sea water side of the engine. I found this diagram. The coolant came out on the port side of the engine after it was pressurized. The starboard side appeared to be just clear water. Water Drain System.JPG
 
Ok, then this is a non-issue
The pump drains from the port side drain and the starboard side w]raw water pump drain
 
I would definitely look into your heat exchanger. I had one that developed a leak this season and ended up replacing it with a new one. I kept the old one and will have it repaired to have a spare in case the one on the other engine decides to develop a leak.
I would also suggest draining and refilling the actual antifreeze. If you have a leak, though unlikely, there may have been some cross contamination. It's also a good thing to replace after a few seasons anyway.
 
gustaf said:
I would definitely look into your heat exchanger. I had one that developed a leak this season and ended up replacing it with a new one. I kept the old one and will have it repaired to have a spare in case the one on the other engine decides to develop a leak.
I would also suggest draining and refilling the actual antifreeze. If you have a leak, though unlikely, there may have been some cross contamination. It's also a good thing to replace after a few seasons anyway.
Click to expand...

I agree, you should not lose engine coolant. Remove the heat exchanger and have it tested/rebuilt over the winter. I also agree with draining all the engine coolant, and changing it while changing the exchanger. There are rubber gaskets between the exchanger and block, also a good time to change the thermostat while in there.

There is no other place other than the heat exchanger that engine coolant can get into the raw water side of the engine.
 
Thank you for all the input. According to my mechanic everything definitely points to the heat exchanger failure. He recommended Mr. Cool Marine as an aftermarket option, www.mrcool.us. Has anyone heard good or bad things about them? There is a $1000 price difference between their heat exchanger and Mercury. That alone sounds pretty good to me!
 
First make sure it actually "IS" the HE. Needs to be pressure tested. The key here is Test first then spend money

Next HE can be fixed by most radiator shops at much less cost then a new HE

Mr Cool is a great place and have good stuff
 
Mr Cool makes solid stuff. That is what I purchased. Only issue I had us that they put one of the fitting slightly off angle so it made it very difficult to fit one of the hoses.
 
I did purchase the Mr Cool and replaced it, then I needed to winterize for the season. I had the leaker checked out. Only 1 bad tube, good as new. Thanks for all of the input.
 
You must log in or register to reply here.
Back
Top