I have run into a issue I just can't seem to figure out. I have a 2003 dodge 3500 5.9. A few details on this truck. The motor has been completely rebuilt. New pistons, rods, heads reworked, intake and exhaust ported and polished, 110# springs. Monster ram intake. Double shot Methanol, Nitrous, 62 mm phatshaft turbo. Custom udc tuning. Air dog df-200. Automatic transmission full billet. Mishimoto radiator, intercooler. Blow off valve. I'm sure you get the picture. My problem is when I go to bring it to higher rpm, say 3000 and above. I will spew water from under the hood like a whale spout. Now, I know alot will say headgasket. But I've ruled that out. I've given thought to pulling the water pump out and drilling two holes in each fin in order to slow the water flow down a bit. Or a larger pulley just to slow the pump down all together. I know I can't be the only one to run across this issue. Any help would be greatly appreciated.

 

I can't speak to what may be causing it, but I'd have concerns about drilling fins regarding the possibility of creating a cavitation situation.

 

Are you sure you have ruled out headgasket? What kind of boost are you seeing? Nitrous, WM and etc?

What you describe is what is known as "lifting the head". In times of excessive boost and rpm, the cylinder pressure can overcome the clamping force of the head bolts (hence why we use studs in HP applications) and this allows separation between the head, head gasket and block. Another reason folks use fire rings or o-ring the headgasket.

I would employ an electric water pump before messing with the stock. The other situation that HP engines run into in high rpm/high power situations is blowing out freeze plugs, usually behind the block or in the head, and this is caused by high pressure coolant and steam formed in #5 and 6 cylinders. The old "opie bypass" was created to solve that problem.

Anyway you seem to have the former problem and wish to address it like you have the latter problem.

Good luck!

 

water pumps are NOT positive flow pumps! research the action of a water pump
and you will see what i mean

 

IMO it is NOT the water pump which is causing your problems excessive coolant pressure, but much more likely it IS excessive heat build up in the rear most cylinders from excessive rpms and the excessive fueling that is needed to get to those rpms that is causing the excessive pressure.