: Plumbing help on 99 STS

04-19-05, 03:08 PM
99 STS VIN 9 motor:

Ok guys as some of you know I am using the N* in my project. I am looking to plumb the motor today/tomorrow and need to know where everything leads from/to. The top big tube goes obviously to the top of the radiator. The bottom big tube goes to the bottom radiator tube on the radiator. NOW here is where I need the help...

1: I am looking to find out where the little tube, above the bottom radiator outlet (5/8" or 3/4") on the waterjacket, runs to.

2: Also the throttle body has an outlet - where does that go to?

3: the left and right side of the waterjacket also have a tube outlet. WHERE DO THEY ALL GO!!!

Let me know if you have any info or cooling diagrams (Chilton was no help)

Thanx a ton gents,
Milwaukee, WI

04-22-05, 11:34 PM
got it nevermind.. just gonna bypass the TB and other little shit

04-24-05, 11:35 AM
Good luck!! :)

04-24-05, 05:51 PM
The two 3/4 or 5/8 (don't remember) go to the heater core.

04-25-05, 12:04 AM
Are you running the pressurized surge tank like the production Northstar applications run...???

Beside the upper radiator hose nipple, or just above it, there is a bolt holding the water crossover to the head that has a hole in it. The bolt is actually hollow and serves as a nipple for a 3/8 hose. That is the vapor vent for the water pump cavity and it MUST be open and plumbed to the surge tank and operational. It vents any vapor from the water pump to prevent it from cavitating and stopping to pump.

The thermostat is on the inlet side of the system...that radiator hose from the bottom of the radiator to the lower radiator hose fitting is on the water pump inlet and the stat is behind that cover. The nipple on that cover you mention is the plumbing point for the heater core return and the pressurized surge tank supply. The heater supply fitting is the fitting on the right rear of the engine off the side of the water crossover casting. That feeds the heater circuit and the return from the heater goes to the fitting beside the inlet radiator hose on the water pump cover.