Hello!

Have been reading some threads here about adding oil thermostat, for example Mocal, Earls or Perma-cool.

That means stock mercruisers (in my case 1988 gen4 454, 50hrs since rebuild) has poor or no oil temp control. Right? Does all oil go thru oilcooler, or is there a bypass and/or thermostat?

Have been thinking of changing to a thermostatically controlled oilcooler. Is there anything except just replacing the oilcooler needed?

(A less expensive solution I also think of is the Mocal sandwich type tstat.)

First Thing I would do is install an oil Temp Gauge ....see where your at ...often wondered what are the actual Temps on the stock setups ....the oil coolers are alot smaller than the HP coolers and maybe merc engineered the coolers to run good oil temps .....are you having moisture problems? ..check the valvetrain for moisture ....m

Actually , I just bought the boat, and the previous owner ran without water thermostats (crossovers, without bypass). This made me start thinking of operating temperatures. Perhaps ok in warm waters, but perhaps not so good in the relatively cold seawater of Sweden.

And I would like to have control of oiltemp. And to start with I want to know how the stock oil temp is controlled. But you say it is not, i e oil is always flowing thru cooler?

As a start I have now installed water t-stats, bypass between crossover and tstathousing, and pressure relief valves. This should help temperatures coming up quicker.

BUT, I do think oiltemp is the most important temp.

FYI here's just another option to add into the mix that actually uses large enough ports to meet the oil flow requirements of a performance marine engine. http://www.hardin-marine.com/p-14580...12-degree.aspx

Best regards

Before I would go overboard I would use my little Infrared Thermometer and hit the oil pan to see just what it is running at.

I have had good luck with my thermostaticaly controlled cooler. look up Mr. Cool on here. I got the one rated to 700hp and with the p/s cooler.