NA Coolant leak on driver side (U.S)

[brian300zx]

Alright so I went to start my Z up late in the evening so it’s pretty cold around 8:00pm drove the car around 12 pm same day just fine. Went to put it in the garage and I see the engine bay steaming, car is running completely fine. It was steaming quite a bit almost thought it was on fire. But, there was a sweet smell indicating coolant. Instantly turned the car off and looked in engine bay as soon as the smoke cleared I saw the header was wet right where it connects to the exhaust. Searched for coolant hoses with no luck couldn’t find any on the driver side or at least none that I know of. Heater hoses are too far to drip on the driver header. I have done the plenum deletes so it’s not those. Really confused because there weren’t any big leaks on the floor either just small drops. Any help would be appreciated thanks!

[Destrto]

Have you checked any places where you've capped lines off or plugged them? There are coolant lines that connect under the throttle bodies, is it wet around that area at all?

[Ace2cool]

On an N/A, there aren't really any lines over there if you've done the delete. You're sure it's not coming from front or back and just traveling over there, where it burns up on the manifold somehow? Otherwise, you're not gonna like what I'm thinking. Possible head gasket failure.

[Ace2cool]

One way to pinpoint the source is baby powder. Spread a little around the area, and wherever the leak is, it will wash the powder away.

[brian300zx]

I was able to find a capped line that had a tear. Had to remove them plenum and now I’ve overtightned a plenum bolt hopefully I can save the threads but it’s looking like I’ll have to helicoil it anyways thanks guys!

[Ace2cool]

Glad it was just a split cap! Whew!

[DCaff300ZX]

Glad it was just a split cap! Whew!

Wow, lucky! And I hope you saw my message regarding the bolts. ZSpec has a nice SS kit that looks nice and obviously will work well, and for a decent price. CZP and Z1 also carry the OEM bolts IIRC.

[brian300zx]

Alright so turns out I’m not as lucky as I expected unfortunately.. the coolant isn’t persistent once the car warms up it no longer leaks? The car does not overheat, it doesn’t leak a lot, there’s no smoke from the exhaust, so I’m just confused as to what I would be. I doubt it would be a head gasket. Car runs fine could it possibly just be bad coolant? I checked my cap the other day and it looked like poop could it just be there is too much pressure due to the bad coolant?

[Ace2cool]

Not gonna be about bad coolant. If it's a small leak, once the car warms up, it's more than likely turning straight to steam and not going to show up as a liquid leak.

[brian300zx]

I have no clue honestly it’s even harder because it stops, I lifted the car and had it on for a while with no visible leaks no wet spots nothing.

[brian300zx]

Coming back to update, it is the delete plug I just didn’t push it in enough got lucky while putting the car away today heard it dripping onto the header and slid my hand down there and sure enough it was wet damn I was starting to get scared!

[DCaff300ZX]

That's good to find, hopefully it's your problem. BUT, another consideration is the heater core under the dash...the design is bad (intake spout down low) in that it allows crap to accumulate over the years around and into the lower three/four cores of the heater core, this corrodes and eventually a pinhole leak/flaking gets big enough and dumps on your carpet. This can take quite some time to completely happen, my NA was as yours for about 3 years before the core finally failed fully and was replaced and my slow coolant loss disappeared, as well as occasional hot running and overheats during summer. OK, also replaced was the clutch fan as it also can be an issue with cooling, and mine was bad.
A coolant pressure test should confirm a pinhole leak somewhere, and if so and you can be reasonably sure your engine bay is tight then try looping the heater core intake and exit hoses (bypass the heater core, not too hard to do) and try again. If no leak indicated after an hour or so of pressure test, suspect that core...