I know lol.

What do you work on at your shop? A little bit of everything?

This. Sounds like it's also due to poor maintenance by the previous owner like the OP stated.

That chunk may have been part of the impeller. I'd plan on replacing the pump and doing a very close inspection of the entire cooling system. If the corrosion is bad enough to eat the impeller, no telling what other damage has been done and what has been plugged up.

The whole reason i swapped out the radiator was that i was having the exact problem im having now with the system only overheating at idle with the ac on. You think running some more cleaner through the system would help or should i plan on replacing the water pump and then run cleaner through it afterward?

I don't think using harsh chemicals is the answer. I would consider it, at best, a temporary band-aid that may do more damage than good. But you may not have much choice at this point. YMMV

I'd do an inspection of the block (you may be able to use one of the cheap borescopes/endoscopes that you can find online nowadays) for corrosion before going too far.

I do have a borescope so i guess I'll have to get that in there, one thing to note though....this whole saga started a couple of months after i had the dealer do a coolant flush. The coolant that was in there beforehand i have no idea how long it was in there but it was still green in color. Before that i had no problems for the close to a year i had the car before i had them flush the system.

IMO a coolant flush, tranny flush are the worse 2 things you can do to a car. I've hardly ever heard a good thing about them It's mostly always been a horror story. Your's is just another one on the list of reasons why not to do it. The bottom half of your radiator could be plugged from the scaling that got knocked loose/dissolved from the chemicals they used for the flush.

If your issue is only at idle you need to look at the radiator fans. Make sure they are kicking up to high speed at idle and they are both working. You could test these with Nissans Consult. Not sure how you would do it without the Consult tool. Uprev or Ecutek may be able to do it.

I am going to ask a silly question. Did you remove the bleed screw out of the radiator when filling with antifreeze?

:iagree:

Chemical flushes worked when engines were made of iron but anything strong enough to eat the corrosion is strong enough to eat aluminum.

Very likely. And any other small passages.

Definitely worth checking before taking more drastic measures.

A non-contact tachometer will tell how fast the fans are spinning (may be able to borrow one at a parts store). Not sure how fast they are supposed to turn but that info may be in FSM. Or compare to another Z.

Have checked this multiple times and both kick on high speed when the coolant temp hits about 214

Flush was done before i swapped out the radiator and rest of system was filled and drained multiple times with distilled water to clear the system of the cleaner. Only thing that i didnt do is backflush the system with the thermostat off

Sounds like you are done and need to take it to someone with more knowledge than you. Just sayin.

Took it to a shop, they are the ones that suggested to swap the radiator and if that didnt work they suggested to do the water pump next

They should be able to check the radiator before deciding whether or not to replace. Same with the pump.

If the radiator is plugged with sludge, the block probably has some sludge buildup too.

I'm still not 100% sure that corrosion/sludge is the problem (although it sounds like the top candidate). If it were me, I'd inspect the radiator and pump before I started replacing parts. I'd do whichever was easiest first. You should be able to get a good idea of radiator condition by pulling the inlet hose and using your borescope.