I have read some threads on oil temps before. Here is my situation. i run 502's with 420 blowers about 600 HP. No thermostats, just crossovers. My oil temps at 3000 rpm and below stay around 180 deg.or so. When I'm running at cruise 36 to 3800 rpm 50-55 MPH for extended time lets say 45+ min. my oil climbs to 220-240 degrees. It will go higher if I run harder. Is 240 deg. an ok temp for oil for extended periods of time. fresh water Great lakes so the water is typically cold.

I don't think there is anything wrong but I have seen people talk about oil temps in the 140-180 range running hard.

you need to keep the oil temps over 212.thats the point that water/condensation boils off.my oil temp on my 502 runs around 230-240 all the time.when i run hard its gets 250.keep a close eye on the oil color.if the oil is getting too hot,then the oil will start to turn a blackish color.hope this helps.

Once oil Temps exceed 240 degrees the petroleom starts to break down which shortens oil life and increases engine wear. Sounds like you could use a bigger oil cooler. Did the boat come with blowers? Do you know if your running the stoc merc oil coolers?

The boat came w stock 93' 502 Carb motors. The oil cooler is a merc cooler. It is the one that is mounted across the back of the engine behind the distributer. It is a large cooler maybe 20" long 3-4 " diameter. Also cools power steering. I think I have seen the smaller cooler Merc has used on other engines that ran along the side of the block, much smaller than mine. But the one I have is stock. Not sure of the part number.

Your temps seem almost perfect as long as they never go over 250f. One thing you might consider is fattening up the jetting in the carbs in the upper ranges. This will help keep the oil temps down if a slight lean condition is currently contributing to the elevated temps.

BT

When you start pushing 290-300 start to worry. Look for a larger cooler.


Ken

have a water pressure guage?

Might wanna consider running a quality synthetic oil. As I understand it, Mobile 1 V-Twin stands up well to higher oil temps. I used it for 4 seasons in my ZZ502/502.

I get about the same as bcfountain...But anyway what oil are you using? timing? boost? CR?

I would say those temps are just about ideal. Blue Thunder is correct about jetting up. 2 jet sizes will bring down the temps 10 degrees or so. If the boat runs well now, I wouldn't bother.