60to0

Have browsed the other threads, and nothing quite matches up, Though i have implemented some of the suggestions from them and retain the same issue.
Car is a 1983 280zx, N/a, automatic. i have replaced, thermostat 190, rad Cap, lines from radiator upper & lower, smaller misc. lines, flushed twice (because it needed it) new spark plugs, wires, rotor cap, oil filter ect.
Car runs like a champ at idle sitting at about a 1/4 gauge for upwars of 45/mins , but when driving 45-50mph it warms to about 3/4 of temp gauge fairly rapidly, then slowly creeps to the end of the "operating temp" bracket..for lack of a better term. and will hold there for a few miles then continues to creep.
Then if you come to a stop take the load off the engine and bump the idle up a little it comes back down to 3/4 and will stay there happily.

zxguy1986

I would check FSM for optimum water temp, make sure thermostat is correct one, check water pump (is it new?) & belt & fan belt for slippage. At cold start, remove rad cap & fill rad to top so you can see if you're getting good circulation in there, responds to throttle.

borini63

You need a new radiator!!!

60to0

water pump is not new, fan and belts are good, just finished flushing it again. still alot of crud coming out of it, new radiator may be in order, or take one of the 4 i have to a radiator shop and have it cleaned. did the rad cap off test, I've got movement, and fluid every where as the radiator started to over flow. going to pull the radiator, and run it to the shop tomorrow, thanks for the replies.

zxguy1986

Yeah, sounds like radiator. Not that hard to test. Aftermarket new is OK if available - but you have a collection! So let us know what you find out!

PredatorZ

Find a reputable radiator shop that can run rods through your radiator and clean out the build up and corrosion. And by doing that if a passage is permanently clogged you will know its time to replace most likely. I am assuming your fan clutch is working properly.

60to0

woo, overheat condition gone, Radiator was partially plugged. thanks for the input folks, Now i need the new head so i can finish building the turbo swap/Megasquirt for the other car.

PredatorZ

Glad to see you got your radiator fixed.
I too am looking into doing a megasquit build. I am going to do all the soldering myself, saves a few hundred bucks and not to brag, but I am an excellent solderer with all the cool tools at work, Ill just build it on my breaks and lunch hour. I'm getting the MS330-K kit with MapDaddy4 Upgrade. best thing is once you build one, you can always move it to another car, esp if we are talking similar model years.

60to0

i have two of the MS-130k built my self, some cursing and hair pulling after not following the step-by-step build and re-soldering they are both up and functional, now i just have to finish the turbo build, and swap motors between the car' staying in CA and the car going to oregon. just can't find some info on the turbo swap that im curious about, still browsing the board's before posting a new question. By the by, found out in conjunction with a plugged radiator, the thermo'gauge was going bad too, soo new gauges for everybody !