Hi Guys - adding oil coolers to a pair of stock Merc Carbed 454s with Gills and closed cooling. Want to make sure I get the most cooling possible as I work these poor motors hard in a big tank of a vessel.

Someone got a diagram they can post that shows best way to flow water and oil in this situation?

Thanks

Swamp

Don't have a diagram but mine went out from the seawater pump to the oil cooler and then from the other side of the oil cooler to the thermostat housing. That's for cooling water.

And I just read you're closed cooling so that won't work. Lol. Then it would be right off heat exchanger to cooler then cooler to housing. To keep it in the closed cooling system.

Water flow from drive, should be, Seawater pump, Oil cooler, P/S cooler, Heat Exchanger, Block, Exhaust

Some folks over think it about the water flow going with or against the flow of oil in the cooler. It's been proven to make zero difference.

The heat absorption of a single pass heat exchanger like this isn't that great. So as Baja Rooster mention it doesn't matter how the oil and water is plumbed. The approach temperature isn't that close any way it's done. However it's best to always put themy as opposite flows this way the coldest water is touching the coldest oil and the leaving water is hitting the hottest oil it's just keeping your heat absorption up at its max potential.

Curious as to what your oil temps are now. I would consider putting oil thermostats on if you go with a bigger cooler. I have a bigger oil cooler and it takes some running to get the oil to proper temp. Even with a thermostat.

Thanks guys - just what I needed. Getting carbs rebuilt as we speak. Will run with fresh carbs and see where temps are. Am also getting props tweaked as I am not getting the WOT RPMs I need (too much prop right now to cruise comfortably and getting on plane is tough). Mills are working so hard the water temps stay at 150-160 and the oil temps creep up and eventually get beyond 250 at current cruise. Bigger coolers should help as will lightnening the load on props and hopefully carbs will be better tuned as well..too lean???

Your water is much colder Bro

;-)