Melling 10778 or 10778C
 

I'm putting a Melling oil pump in my motor and in discussing it with the tech guy from Melling her recommended not to use the 10778C pump. He says the anticavitation groves will make the oil pressure too low at idle. I did tell him that this engine will spin up about 5400-5600 and it is in a twin turbo offshore boat. Thoughts?????

use the 10778.the tech was correct,the 10778c is not recommended for marine use.i really like the 10778 pump.

+1

I ran the 10778C for 350-400 hrs, and just took my engines apart for refresh this spring. The bearings still looked new, as did pretty much everything else. Except for some carbon on the pistons and weak valve springs. I ran 40wt synthetic in it and always had great oil pressure when cold starting (50-60 psi) and anything above 1200-5600 rpm when hot (35-60 psi), but once it was warmed up and idling I had about 8-12 psi at 800rpm in gear. It drove me nuts so I am NOT going back with the "c" and chose the regular 10778 for this rebuild. Hope that helps answer your question.

I ran the C for awhile, results above are the same as mine, except sometimes (may have been the sender) it looked like a couple of pounds at idle warm.

I use the C in 3 motors but never see under 30lbs

Remember, 5500 rpm's is slow for an engine. We must sometimes remember most marine engines do not spin fast.

I have a C in my 548 and had 20 psi hot at idle.