An annoying problem that I just can't solve :(

[Kenneth K]

I've been tightening to the point where the wire could snap if I tighten further, but I've been risking it in the last few days. I'm also concerned the wire will cut the hose if I tighten further.

If you're able to get the wire that tight around the hose but it still see leaks, are you sure the leak is from the hose? Could it be a pinhole leak where the barb is soldered on to the tank? Or from the cap, running down onto the hose?

You could try replacing the tank altogether. I think @peaman has posted pics of a replacement accumulator tank that's a lot more slick than what Ericson used. Or, unscrew your tank from the bulkhead temporarily so you can get a second seizing wire on the other side.

 

[bgary]

I added a coolant/overflow tank to mine several years back. Plastic tank that I mounted on the bulkhead above the manifold. Works OK, and it's interesting (?) to see the level change between cold and hot (yeah, I know, I need a better hobby. but I digress)

When I first put in the tank, I had coolant leaks. Couldn't figure out what was going on, all the connections were tight. Turns out, the plastic tank itself was leaking, at the seam between the tank-body and the hose connection. Took it back, got a second one. Same thing. The third one didn't leak, so it's still in the boat.

Only reason I raise that is to wonder - is there any chance the tank itself is leaking, rather than the hose connection?

 

[gabriel]

Look for ‘fuel injector’ type hose clamps, they’re thinner and better for small things.

My opinion: I don’t think that nipple should leak without a hose clamp though. I would investigate the tank or cooling system further.

 

[Frank Langer]

Thanks everyone! Lots of good ideas for me to consider and try. I'll try to post a pic in coming days, and hope I can solve this.
Thanks again for your help!
Frank

 

[toddster]

Clamptite tool

Cheaper knock-offs can be found on Amazon & etc.

 

[Frank Langer]

Clamptite tool

Cheaper knock-offs can be found on Amazon & etc.

Wow, that looks very cool and might be what will finally overcome this leak! I've never seen this before.
Thanks!
Frank

 

[cruis-n]

I'd recommend that you take a look at the radiator cap, perhaps it should be tested/replaced. It sounds like the cap may be opening at low pressure, thus having hot coolant flowing out, necessitating a clamp on the hose.

On my 35-3 there was one cap on the engine and one on the remote metal expansion tank. As I recall, they were different pressure ratings. Ended up with the higher rating on the engine and a slightly lower one on the expansion tank (don't recall the ratings now). I never had any leaking issues (knock wood) with the overflow hose on the remote expansion tank.

 

[JSM]

So use of a more sophisticated relief cap which can relieve into a zero-pressure overflow tank which will then be emptied by vacuum back into the engine cooling system as the engine cools down after shutdown addresses all of those issues.

Exactly. The tank is there to retain coolant and return it to the system in an overheating event hence the name "overflow tank" As I said up thread I run with my tank empty and have zero issues and see so reason to keep coolant in the tank at all.
My point being that if the OP kept the overflow tank empty the leak would not exist.

 

[peaman]

My engine mounted cap is 13 psi while my higher remote accumulator cap is 7 psi.

 

[bigd14]

Turns out, the plastic tank itself was leaking

I had exactly the same issue. Replaced it with an inexpensive metal tank and fittings and no problems since.

 

[Frank Langer]

I've added the pics, still thinking about next steps given the range of suggestions.
Thanks again!
Frank