Bdysisun

i have 2005 350z with roughly 160k miles on it, recently i discovered that my car is draining coolant like theres no tomorrow and leaving bunch of mark on top side of radiator and around it. Also right after i drive, i can see little bit of coolant dropping from upper radiator hose and radiator cap.
Do I need to change the radiator or is it something else i should be checking?
Upon checking it seems my radiator cap and upper radiator hose/clamp were fine which i thought the initial problem would be..

MicVelo

Pressure test then replace what's leaking.

Abandonedxwolf

If you could get some better close up pictures that would be great. I'd like to be able to see a better close up of around the radiator cap, also some close ups at the radiator seem at the top (the section where the plastic top and metal body of the radiator come together) and maybe another close up of the upper radiator hose where it attaches to the radiator

Yes definitely a pressure tester would help even more with finding the leak too, it will basically just pressurize the radiator with all of the fluid in it and if there is a leak this pressure will start to make the fluid drip, drizzle, spray, at. Depending on the size and severity of the leak.

Even if you don't have a pressure tester, a lot of the parts stores usually have a loaner set that they'll let you take out.
Alternatively there's also the option of adding UV dye to the coolant. How I would do this is spray all that's on there currently down with water to get it all off then add the dye directly to the radiator rather than the reservoir. Next drive around for a little bit (doesn't have to be anything too crazy, preferably allowing it to get up to temp and thermostat opens cycling cooling through system . Then afterwards use a blacklight (uv glasses can also be pretty helpful) we and check along all of these areas

icer5160

iTrader: (4)

Late to the party, with that much spray at the top, I would be confident in saying your radiator endcap seals have failed. Time for a new radiator.

While you're in there, replace the cap and hoses. Use OEM hoses and clamps to ensure no future leaks.

If you have access to a pressure tester, or wish to purchase one, that will help verify the leak point.

Cheers!
-Icer

Abandonedxwolf

To add on this it's kind of 50/50 between csf rad and koyorad (this is for the majority of cars) but for the z from what I've seen, a larger percentage go for the koyorad, personally this is what I have too and it is absolutely perfect.

​​​​​​As for the hoses I just want to add one more good and reliable replacement which would be the Z1 silicone radiator hoses

icer5160

iTrader: (4)

I agree on the Koyorad recommendation, but completely disagree on the Z1 Silicone hoses. Every online photo I have found of these shows the hoses sweating water. Not only does this look nasty, but it means checking and topping off coolant levels more often. Silicone hoses are great for higher pressure coolant systems typically found in track/race use, but honestly not a good choice for the reliability of a daily driver.

That being said, not all Silicone hoses are made equal and it's possible that other brands don't have this problem (Samco is a top brand). My buddy is using CZP silicone coolant hoses on his Z32 and I've never seen any sweating issues, but I have read on other forums that CZP hoses can also have this problem. I'm sure both companies have them manufactured in China.

You can read all about this issue and why it happens in an article from Motoiq here.

Cheers!
-Icer

bre240z

ditch the silicone hoses and just use oem

MicVelo

This. ^^

There are zero REAL advantages to silicon hoses other than aesthetics (when they're new) and maybe are a tad easier to take off if doing so frequently... like maybe a race app. BUTT.... that bit of extra slippery is what makes silicon a non-starter. Leakage, weeping, and porosity. Waste of money, then when the thing leaks and/or weeps, well, there goes the aesthetics. Seen far too many of these (even lately) that look worse than a stock black hose - which work better than anything else.

This post is a one hit wonder anyhow.

bmccann101

iTrader: (16)