okay im pretty new to this forum. i recently took my z out of storage and took her for a drive. went about 100 miles, then i found myself merging onto the highway right next to a sti, long story short, i brought it up to maybe 130ish, noticed my temp gauge rising. never hit the red. but it was on its way, took me a few miles of driving 65 to get it to get back in the middle where it usually is, i'm running stock boost, it does have a jdm motor, full of coolant, i cant seem to figure out why it wants to over heat on me, this just started to happen, last year it was fine.

water pump??

i didn't do the timing belt or water pump before installing the motor, i know, preventive maintenance. im hoping its something else. if there's anybody out there thats had this happen to them and u might know of a few tricks or hints before i rip into the water pump

Um, you took it out of storage and took it up to 130mph? not the best of ideas.... And street racing?

Could be water pump. Where was your oil pressure? How long was the car in storage? No coolant leaks whatsoever?

you might wanna try a pressure test on the radiator. could be leaking from there. it could be various things since it was sitting in storage for a long time.

if you are overheating at speed it generally means a clogged radiator, air in the system can be an issue as well but if it idles cool and raises temp with speed it's the radiator

I would do the easy stuff first before going after the water pump. Pressure test the coolant system, test your coolant to see if its still good, flush your coolant system. Possible that you had some rust or something in your system when you stored it. That could've settled in your radiator or thermostat causing a blockage.

well its not going to be the waterpump unless it is leaking from the front of the engine which would mean that your bearings have gone out. The waterpump is constantly turning because the crank is constantly turning. Its not a very complicated setup, the only way that the water pump couldn't be doing its job and not leaking is if the blades on the inside of the pump have been grinded off like mine were. In that case it may cause it not to pump as efficiently and hence the reason you're overheating more at a high rpm. I would try flushing the radiator first to see if it clogged also check and see if there is a lot of debris in front of the radiator, that happens alot in Zs and most times you cant tell just by looking under the hood (less likely the problem though). Could also be the clutch fan gone bad, check and see if it doesn't spin right when the car is idling if you have electric fan convert then check to see if they spin every once and a while(they spin at a certain temp so i'de wait till the engine is hot), It'll look like its freely spinning kinda like its not catching right. Also could be the thermostat in some strange way...thermostats are weird like that?? They stick at certain points and stay open at others because they're spring controlled, but either way theres not to much stuff that's very complicated about the cooling system except the lines under the intake that are mostly used for cold weather. Good Luck!!