We changed the drives from XR/ITS to brand new Imco SCX complete drives. My 2006 Fountain Lightning / 600sci (closed loop) came from the factory with a single high speed pick up and the XR drives w/ low water pickups feeding one huge strainer. This set up worked great for 8 or 9 years. Now, with the new drives the strainer is getting sucked almost dry when I speed up faster than a slow cruise. My water temps shoot way up and one of my headers turned gold/blue and melted the 4" rubber coupling hose from the exhaust pipe to the tail pipe from insufficient cooling. Only other change was plumbing the intercoolers to pre steering fluid cooler. X dim stayed exactly the same as well. Any help would be greatly appreciated.

Have you looked at the water inlet in the nose cone? See if you have a slot or just a 1/4 in hole. It needs to be a slot and you may need external water pickups

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Yes I have those slots on my lowers as well as a 1" high speed pick up on transom.

eliminate the one on the transom my cat has scx and that slot provides plenty of water

Could the o-ring gasket be not set right in the drive and pulling air? Seeing you are sharing the sea strainer it would be hard to see what side ( if it is pulling air). But look in the strainer at idle or high idle and see if there is air bubbles.

After talking with Reggie we decided that the slots in the SCX lower is not big enough to feed the boat with enough water as it is set up. Fountain used to enlarge stock XR lowers to increase flow. SCX are smaller than stock XR. We enlarged them like the photo drpete3 posted and will test hopefully Thursday.

I dont think thats it , I ran the standard SCX,s with sportmaster lowers with a high X and never had a cooling problem , if I remember right the sportmasters had a small inlet . You have the intercooler tied in with this also ?

Yes, intercoolers are tied into the system.

I'm sorry, my lowers were in fact sportmasters. SCX lowers have smaller inlets than Sportmasters in stock form. Fountain enlarged stock sportmasters at the factory on my boat, therefor my new SCX lowers had about 1/3 the inlet size of my original Sportmasters. They were also further back on the cone. This is why we enlarged them and moved the slot forward to the tip more.