On my project i have 2 standard size Merc. coolers.
One for Oil/P.S. and the other for Trans..
I have them water routed in-line,meaning back to back connected.

I can run all day at 3,000 rpm no problem 110-120 deg. but if i push it up around 4000 rpm temp climbs and seems lack of flow.

This is raw water cooled,sea water pump belt driven; belt tight .Cross over w/no by- pass,thermostat gutted.
Pick- up depth about 1/2 depth.Good Imco manifolds.

My question is should the Coolers be water routed parrell instead of inline?
Anyone running them inline with no problem ??
Thinking too much restricition to get thru the honeycombs.


Thanks for feedback !
Ken

In-line is fine. The big question is if the have the oil flow and thermal movement capacity for the engine you have. The stock Merc oil cooler is adequate up to about 375 horse on a BBC. Above that, they not only don't allow for enough throughput to cool the oil, they'restrict oiling, starving your engine's need for volume.

You're not doing your engine any favors by operating it cold. You ned to get some heat into those cylinders. You also should run an oil thermostat- if your oil isn't reaching 212*, you're not removing the condensation from it.

Read this-

http://www.offshoreonly.com/forums/s...3&page=1&pp=20

Thanks Chris.
Yes it is a stock BBC 330 hp.
So far no condensation,but i understand what your saying.

Added info

Impeller is low hr.
I guess i'll back flush coolers also to make sure clear.