Circulating Pump Bypass Hose
 

I'm putting circulating pumps back on my engines due to the cold water that I boat in. With the cross overs the engines were never getting any heat in them. My current intake manifolds don't have a provision for the bypass hose, would you drill and tap the intake or could you drill three 1/8" holes in the t-stat? Which is the better way? I don't want to have any cooling issues. Thanks

I boat in Lake Huron in early spring, water temp was 34 degrees, and yes that is Fahrenheit. I have a 522 with a Stainless Marine crossover with the bypass port. I am running a Stewart racing 160 degree thermostat that has three 3/16" holes in it. Now on the extremely cold days I pretty much stay around 130-135 unless I really pound and then it will get to 145. Once the lake get above 55 I have no problem getting to 155, which seems to be the temp I run at with this thermostat. I would make sure your thermostats are working properly, when they get old they start to open sooner.