Leaking Coolant - G21

[morrow]

Our 2020 G21 started leaking coolant yesterday. Found it in the bilge. Significant enough that I had to fill the reservoir and it went down to about 1/4 of the reservoir in 24 hours. Hadn’t been having any issues. No engine codes. Can’t find the leak on any hose, and everything appears dry. It appears to be on the floor of the starboard side engine compartment somewhere. Any thoughts on things to check? I was hoping maybe a hose had just come loose but haven’t found it yet if so…ZZ6 450 6.2L engine

[NautiqueJeff]

Does your boat have a heater? If so, check the lines that lead to the heater core. Those are famous for leaking coolant. Normally they can just be tightened back up.

[morrow]

Yeah I have a heater, I checked the heater core and it looks good, whole area in front of driver space is dry and clean. I’ll have to try to trace the cables to the engine when it cools off. Should it connect on top or is it down underneath?

[steve-o76]

I have a 2020 GS22 with the ZR4 engine. I also have a coolant leak (the green in the bilge is unmistakable) and just found the culprit this past weekend. As it turns out, the coolant reservoir itself is leaking at the seam where the top and bottom halves come together via the manufacturing process. The kicker is that the leak can only be "seen" (i.e. a visible drip) when the engine is hot, presumably causing the plastic reservoir to expand at the seam and become compromised.

The coolant reservoir sits fairly close to the exhaust manifold and we are guessing that the heat from the manifold has weakened the seam over time (I'm at 530 hours). When cold/cool, the seam appears to be strong enough to hold, however, when it things heat up (the tank and coolant) the leak reappears. The seam appears to be slightly cracked and brittle in the area nearest the manifold where the leak occurs.

I purchased some JB Weld high heat epoxy and plan to apply that to the seam of the reservoir later in the week. I may also apply a layer of heat shield to the manifold in the area that is in closest proximity to the tank. Hopefully that will take care of my problem. Any critiques of my proposed fix are welcome.

Ball of Spray has a good discussion about the issue from a couple of years ago:
https://www.ballofspray.com/forums/t...ique-200-60-l/

Just something else to consider.....

[morrow]

I have a 2020 GS22 with the ZR4 engine. I also have a coolant leak (the green in the bilge is unmistakable) and just found the culprit this past weekend. As it turns out, the coolant reservoir itself is leaking at the seam where the top and bottom halves come together via the manufacturing process. The kicker is that the leak can only be "seen" (i.e. a visible drip) when the engine is hot, presumably causing the plastic reservoir to expand at the seam and become compromised.

The coolant reservoir sits fairly close to the exhaust manifold and we are guessing that the heat from the manifold has weakened the seam over time (I'm at 530 hours). When cold/cool, the seam appears to be strong enough to hold, however, when it things heat up (the tank and coolant) the leak reappears. The seam appears to be slightly cracked and brittle in the area nearest the manifold where the leak occurs.

I purchased some JB Weld high heat epoxy and plan to apply that to the seam of the reservoir later in the week. I may also apply a layer of heat shield to the manifold in the area that is in closest proximity to the tank. Hopefully that will take care of my problem. Any critiques of my proposed fix are welcome.

Ball of Spray has a good discussion about the issue from a couple of years ago:
https://www.ballofspray.com/forums/t...ique-200-60-l/

Just something else to consider.....

Thanks, I'll check that! I am at just under 500 hours now as well. We just got home from vacation, and of course, I can't find anything at the moment with it cooled off and out of the water. So I'm going to have to get it running and hot again to hunt it down.

[aerojust]

Like you I had coolant in the bilge. We ran the heater the other day for a long time. I did a quick look and the line on the back of the motor with the shot off value for the heater looks good. Did not find where the other line enters the system. Did not look very hard either as no time today, There is coolant on the port side at the very back on the carpet by the fuel water separator canister on the carpet. The tank was down just an inch maybe. It is like is is slowly spraying out.of something. Should have time this week to better troubleshoot. If I get it up to temp and pressure I am assuming It will be very obvious.

I had the same reservoir issue this spring. The new reservoir has a different shape and has more room between the exhaust and the tank.

[morrow]

Update: Still have not been able to find the leak. I do have the spider cracks at the edge of my resevoir, one in particular looks like it probably goes all the way through. Maybe this is where it's leaking, or allowing air in which is causing issues elsewhere. I have a few months left under warranty, so I'm reluctantly taking it back to my dealer.

[aerojust]

Jeff pretty much nailed it in my case. After I pulled the port side dividers out between the engine and the ballast compartment so I could crawl back and see the front of the engine it was clear that the fitting on the coolant hose coming off the coolant pump and going to the heat exchanger was covered in antifreeze. The clamp so loose I could move it with my fingers. This hose is right beside the red hose that runs to the heating core up in front of the pilot seat. I am assuming this is the heating core supply but am not sure. The other heating core red hose is on the same side of the engine (Port) but on the back (facing the front of the boat). I tightened the clamp back down and hosed all the antifreeze off the carpet. Will have to check it out again after I run the boat later this week. I fully suspect this is the fix.


Finally something easy and no cost to fix!!!

[morrow]

Closing the loop here. Took the boat in to the dealer. Cracked heater core. Not really sure how that could have happened when it hasn't been cold but that's the issue.

[mikenbike211]

thats very odd! those are full of antifreeze so freeze damage wouldnt be the cause

[jpwhit]

Typically a solder joint breaks due to the thermal expansion and contraction of the heater core.

[morrow]

Update: It was a cracked heat exchanger. They had to replace it.