Pressure check on closed cooling side

[darrenlife]

Hi, my new to me 410SS has a small leak on the closed cooling side. I see some drips in behind the heat exchanger and would like to pressure check the system to see if I can pinpoint the leak. I have mercury horizon 496 with the coolant reservoir. I have a Stant pressure tester but don’t have the correct adapter to fit on the reservoir cap, wondering if anyone has any ideas? I have contacted Stant to find out what the correct adapter would be, just wondering if anyone has similar issue and what the remedy was. Thx!

[390Express]

Not too familiar with the 8.1s, does your motor have a radiator cap style inlet near the thermostat housing?

[pepmyster]

Yes it does, I had these motors in my other boat. I'm surprised you don't have the adaptor. The best way is through the reservoir. Is there no way to adapt one of your connectors with the kit, If I remember right, the cap was a standard type. Can you not use a mirror and a light to see where this leak is coming from? Or a camera or scope?

[mjk1040]

Put a valve stem in another cap and use a bicycle hand pump with a gauge. A bigger tester kit would have adaptors.

[Viper]

Trying to find out what version you have. There was a bulletin years ago but I'll need a serial number to see if you fall into the range of affected units. I can run the number next week.

[darrenlife]

Qr Bbpost Not too familiar with the 8.1s, does your motor have a radiator cap style inlet near the thermostat housing?

I don’t have a typical automotive style rad cap on my heat exchanger, only fill point is the reservoir cap which has a 15psi rating