Oil Cooler for Perkins 1.108

[Astral Blue]

I was running the boat under load this weekend for an extended period. The water temperature was in the mid 70's, so my engine was essentially being cooled with the warmest water of the season. As I continued at full load for about 15 minutes, I noticed my oil pressure dropped by 25 percent. I headed back to the marina, docked, and allowed the engine to cool for a few minutes (temp dropped to 160 degrees). I then started it again and noticed the oil pressure back to normal.

I'm guessing taking the engine to 180-190 degrees compromises the viscosity of the oil and causes the pressure to drop. I'm considering two things. First, I want to install a larger heat exchanger. I have constantly read accounts regarding the original heat exchanger on it not having enough capacity. Second, I'm considering installing an oil cooler. I notice many sailboats with the Perkins 4.108 do have an oil cooler (for crankcase oil).

I want to install the oil cooler first, as it would be the easiest fix for the oil pressure problem. But I want to eventually upgrade the heat exchanger to one with more capacity.

What has people's experience been with oil pressure dropping on the Perkins 4.108 as engine temperature increases? What capacity oil cooler would be best?

Thanks in advance for your help.

[S/V_Surya]

If you are using 30 weight diesel oil your pressure should not drop that much at your running temps. Mine stays pretty steady. Could be a sensor problem. My oil pressure increases as I add load.

I do have an oil cooler and I am surprised you do not. It also cools transmission fluid.
I guess we need to hear from those that also do not have an oil cooler....

[Astral Blue]

Originally Posted by S/V_Surya

If you are using 30 weight diesel oil your pressure should not drop that much at your running temps. Mine stays pretty steady. Could be a sensor problem. My oil pressure increases as I add load.

I do have an oil cooler and I am surprised you do not. It also cools transmission fluid.
I guess we need to hear from those that also do not have an oil cooler....

I have been using Delo 400, which is a multi-viscosity oil formulated for Diesels and rated at 15W40. I was thinking of using 30 weight oil when we first repowered the boat with this engine, but was talked out of it by my mechanic.

[jimjimmyjimjim]

I know this post is old and should be closed but I thought I'd add this for people's info.
Perkins manual says that for the 4.107 or 108 with a closed system, the proper coolant temperature for pressurised system is "in the region of" 190 degrees F. For a unpressurised system it is 170 F.