Hey guys I could use some advise here before I start dropping money for new cooling system parts. My 350z just randomly started overheating on me but the weird thing is it only over heats when the RPMs are over 2000, when they are brought back down below that the car cools back down to about normal. Its almost like something is restricting the convection from keeping up with the engine. I've checked the coolant level and it is good in the both radiator and the overflow. I havent lost any coolant, oil looks normal, and the Rad fins all look good with no debris blocking it. I know the water pump is timing chain driven So it's rare for them to stop working but unless the thermostat is stuck partially open or something I'm not really sure what would cause that. I do have heat in the car and the Antifreeze looks super clean in the Radiator. I think I'm going to start with the thermostat because it's the simplest and cheapest thing to start with but any input would be awesome. Also the car has about 80k on it and I'm not sure if the system has been flushed.

 

Could be the t'stat. One way to tell is to let the car warm up and feel the radiator hoses - if one is hot and the other cold, change the t'stat. Only use OEM Nissan. Bleeding air from the system in these cars is a giant pain in the ***. Read the thread "Coolant purge nightmare" and consult the factory service manual before attempting this, ot take the car to a Nissan dealer. Don't screw around with this and risk the engine - HR's are not happy when overheated, and you don't want to have to do headgaskets.

 

Thanks I'll check that out I had heard that the HR's are very temperamental with the cooling system.

 

I've never heard that on the HR but the DE is known for having trouble with air bubbles when bleeding. The HR is not as bad because the fill point is higher.

I would also start with checking the thermostat. Get yourself a spill free funnel for bleeding and follow the FSM! Pour slowly and don't forget the bleed screw in the heater hose.

 

+1 on that funnel - I've got one.

 

Let us know how the thermostat change / coolant flush goes. From personal experience, I'd stick with the OE Nissan coolant and thermostat (as stated above).

I keep an eye on my coolant's condition every six months or so using a refractometer. I use a UView 550000 Airlift purge tool to drain and fill the system. It takes less than 5 minutes and I've never had problems with air pockets.

The funnel's good too, but it takes a while.

 

You might have to burp the system. Try squeezing the hose (Warm engine) that goes directly to the T-stat to push warm coolant to open it up.

 

Thanks for all the advice guys I'll be doing the T-stat this weekend. Ill let everyone know how it goes. finger crossed it's not the water pump lmao

 

Are you saying squeeze the return hose while the engine is warm to see if the T-stat will open?

 

Yup, that's what I did on mine to sort of pump coolant until it opened and to move air out in between.

 

Hey guys just changed the T-stat and it fixed my issue... I also installed a KOYO 4 core aluminium radiator and put ISRperformance silicone hose's on... because I wanted to lol. As far as bleeding the coolant system it was very simple with the Leslie funnel. I just had a buddy watch the bleeder plug hole on the heater hose and tell me when it was about to overflow. Also I filled very slow to avoid any trapped air. Fired it up let the T-stat open turned it off and topped it off. The end... I can go further in detail if anyone would like but it was all pretty straightforward.

 

Hey! Can you go further in depth for me? Same problem, wondering if it’ll require the same solution.

 

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