Fresh Water Cooling

[TJ]

1992 285 HP 351 Ford and we had a San Juan Engineering fresh water cooling system put on. The thing runs fine at idle and at RPM. The problem is when you slow down after running at RPM the temp will start to climb to over 200. The quick fix is to run the engine at neutral at a higher RPM and the temp will come back down. What the heck. we changed

Impeller on the raw water pump

do we have the wrong thermostat in there?
What would be the correct part number?

Thanks in advance

[agardunia]

RE: Fresh Water Cooling

Who put the kit on? Has it always done this? I just put a monitor heat exchanger on my 1998 AN and my temp runs from 160-170.