Yanmar 2GM20F Expansion Tank Drip

[Panera]

I've been chasing a coolant drip associated with the expansion tank. After each cruise, there is coolant in the engine basin, not a lot, perhaps a couple tablespoons. I've replace the radiator cap, replace the Expansion tank and still having the same issue. The engine does not over heat, no alarms, no steam and run great.

The expansion tank is filled to the low mark when cold and has never over flowed that I can detect. There is a tiny hole in the expansion tank cap where the coolant seems to leak from.

Anyone experienced this issue?

 

[kappykaplan]

Get a new cap for the expansion tank?

 

[Ralph Johnstone]

I'm amazed that you're the only person I've ever seen to raise this question because anyone with a Yanmar one or two cylinder engine will undoubtedly have the same problem.

If you take a look at how the little tank is mounted :

................ you'll see that it's subject to any and all vibrations coming from the engine.

The next time you return to your marina and after tying up, leave your engine on idle (800 RPM) and remove the cover over your engine. You will then see that the overflow tank will be sloshing around like a washing machine on steroids and every so often a drop of coolant will escape from under the lid. This is what's happening when you are entering your marina at minimum speed. Unfortunately, the lid does not screw on so a gasket under the lid is of no use.

The way I eliminated the problem was to stuff a large wad of plastic scouring pad into the overflow tank and this stopped the sloshing against the underside of the lid.

No more coolant under the engine.

Ensure that the pad is made form coarse strands that will not break while in use. Test before inserting it in the tank.

 

[Panera]

Ralph, thanks so much, it makes perfect sense. I do know how much the engine shakes, but your point never occurred to me. I'll definitely give it a try.

 

[ggrizzard]

Another possible solution would be to mount the expansion tank to the bulkhead in the engine compartment, which doesn't "shake".

 

[kappykaplan]

Another possible solution would be to mount the expansion tank to the bulkhead in the engine compartment, which doesn't "shake".

That's what I did when I added an expansion tank a few years back.

 

[Ralph Johnstone]

Another possible solution would be to mount the expansion tank to the bulkhead in the engine compartment, which doesn't "shake".

What any sane person would do, except when dealt one of these :

There is approx. 1/2" to 3/4" clearance all around.

 

[kappykaplan]

What any sane person would do, except when dealt one of these :

My expansion tank is located in the lazarette for that very reason!

 

[Panera]

Thank you for the suggestion to mount the tank in another location off the engine. Unfortunately, the engine cover fits tightly over the entire engine with no option to mount the expansion tank..

 

[Tally Ho]

Another possible solution would be to mount the expansion tank to the bulkhead in the engine compartment, which doesn't "shake".

My expansion tank (2GM20F) is mounted on the bulkhead….no sloshing or leaking.

Greg

 

[Justin_NSA]

Mine is mounted to the bulkhead beside the engine. Came this way as far as I can tell. No issues here.

 

[Ralph Johnstone]

All right, all right, all right.
So most of you are bragging that you're better than I am because you've managed to attach your overflow tanks to a sturdy bulkhead and avoid the vibration. When your engine is in a Nike shoe box, you're not so lucky :

I've even looked at leading the hose back and down down to the aft aft where I do have the room to install the overflow tank.

The big problem with that location is that it's a little over 24" below the level of the radiator cap and I'm not keen on lifting the overflown coolant that far after the cooling system is shut down and starts to cool.

Any other ideas out there ?

 

[Tally Ho]

Yes Ralph, that is going to be a tough installation in the shoe box.

I wonder if the tank will work right if mounted 24” below the HX neck? I imagine the overflow will be fine, but will it be able to suck it back up to the HX as it cools? Seems like a long way.

What if you put some sort of hose on the cap (with the vent hole that seems to slosh out when the engine is running), and lead that hose to a collection vessel of some sort down in your bilge. I assume the vent hole is critical, but if you installed a small hose barb into the cap, and led a hose down to a can or something in the bilge, any AF that escapes the vent ends up in the can in the bilge…

Kind of like folks do with their PSS….

Just a thought.

Greg

 

[Ralph Johnstone]

What if you put some sort of hose on the cap (with the vent hole that seems to slosh out when the engine is running), and lead that hose to a collection vessel of some sort down in your bilge.

Thanks for the thought Greg. If the tank were any kind of sealable container, that would work however, the tank cap sort of flops down on the tank neck without sealing and stopping any sloshing in the tank at low, bone rattling RPM's is impossible to catch unless the whole tank sits in some sort of bag which is tubed down into the bilge.

I wonder if the tank will work right if mounted 24” below the HX neck? I imagine the overflow will be fine, but will it be able to suck it back up to the HX as it cools? Seems like a long way.

My thoughts exactly when I first looked at this some 20 years ago. I'd rather not lift it that far. Mounted on the engine, it's almost level with the radiator cap.

What I have now works perfectly but it's the OCD inside of me that wonders how long that plastic scouring pad can put up with these bone rattling episodes of leaving and returning to the marina before one or more threads of plastic break off and are sucked into the coolant and from there ......... ?
How about a channel in the block ? OMG don't go there. Time for another Prozac.

I took the pad out to inspect the inside of the tank a few weeks ago and it's still as solid as the day it went in. Maybe it won't cause problems. Maybe I'll also take a couple of extra Prozac and I'll forget it's even in there.

 

[Scott T-Bird]

So that's where it's coming from?!?! For the past 3 seasons I've been wondering why there is a small amount of coolant in the pan beneath the engine that I have to clean up once in a while. Since the pan doesn't drain until there is an overflow, I simply wipe it up with a Bounty quicker picker upper every month or sooner, depending on use. BTW, mine is mounted on a bulkhead, not the engine block, so not sure if this is cause in my case. I guess I'm still looking ...

 

[Ralph Johnstone]

mine is mounted on a bulkhead, not the engine block, so not sure if this is cause in my case. I guess I'm still looking ...

OUCH. I doubt very much if it's coming from the overflow tank. How about the coolant pump shaft seal ? Any sealant from that is going to splatter when it drips but maybe feel around the seal after the engine has run for awhile.