Leaking heat exchanger

[Joe]

About 10 miles from the trailer, my rear heat exchanger started leaking while going up a tough hill.
It looked like a dog taking a leak on a fire hydrant except it was going onto my track where it goes around the rear rollers.
When I got the other sleds unstuck and turned around, I turned my attention to the leak.
I loosened the pressure cap to relieve the pressure.
There was a sucking sound and the leak speeded up.
We put a quart of water in the radiator and tightened the cap to get going again.
About five miles later, we stopped and refilled the radiator.
We put the VMAX on the trailer and unloaded the spare sled.
The trailer was awash in green when we got back two hours later.

I took the rear heat exchanger off and found a 1/2 inch section of the gasket had been displaced INTO the coolant cavity allowing the coolant to escape.

Why would the gasket fail INTO the cooling system?
Has this happened to anyone else?

Yamaha wants $3 for a new gasket and $15 to ship it to me.
For $18, I can make one from gasket material.
What type of RTV could I use to make a gasket that will last?

[Vmax540]

Never have I seen a heat exchanger fail...... lucky you ! Joe don't have a clue why it would suck in unless some how the leak with heating of coolant and cooling of snow created a vaccum ? I'd ask at a good automotive supply store on what sealant to use if any at all ?

[Joe]

They recommended 'high temp red RTV sealant'.

I applied it as recommended and it worked great. No more leak.