I am having a 502 mpi built w/ an upgraded cam and Cmi high top headers but basically stock. I have recently had the water line and fitting replaced in the transom assy, corrosion was clogging it off, new sea water pump and new circ pump. The builder says he will not warranty it unless I get an off shore cooling setup. I understand the 502's do not have cooling between the cylinders but is this overkill. He is also going to drill a 1/2 hole in the stat housing to provide cool water directly to the circ pump. If I go w/ off shore will I # 1: loose speed due to the pickup. 2: need to buy a strainer. 3: Increase chance of picking up a bag or other garbage and clog my intake. 4: will I do damage to the drive if I block off the cooling water, do I need to drill a hole in the jacket to keep water flowing. 27' Powerquest, should run upper 60's hoping for 70 at 5100 rpm 25" mirage. Looking for any knowledgeable comments.

The builder is either:

A: Trying to sell you a bunch of stuff you dont need or

B: Trying to get out of having to warranty it

Either way it sounds odd and a little scarey.

Its a mild 502, stock mercury cooling should be just fine.

I would def add a strainer it will save your azzzz

I don't think its necessary to add anything to the system if you put the new hose in the gimbal it should be good. If you do put a pickup on the bock of the boat don't put it directly in front of the propeller. And you will want to cut the hose in the gimbal to help cool the drive.

Run far away from that builder !!!!! 525s pull water through the drive. No issues. He,s full of **** !!!!!!

As do 575's and 600 sci

We are going to need information on this "builder"

I'm thinking / hoping there is a translation issue between builder and customer.

Why not install a water pressure gauge on the dash. It should not exceed 20 psi a
@ WOT. If you don't have enough pressure, fix the problem. Plus one on the strainer recommendation!

His problem isnt with the cooling system, his problem is with the shop.