Here's the background story: I purchased a very gently used Zex wet kit (350z specific) last summer from a guy off craigslist. It was in excellent condition and included the original receipt with a sale date of Nov 2010. Anyway, I just got around to installing it (separate thread to follow) and much to my dismay, when I opened the bottle to check for leaks, I heard a hissing coming from the intake tube.

Videos of leak (note that I originally thought the fuel solenoid was leaking too, but it isn't):




It occurred whether the system was off or armed. Although it was a small leak that took about 45mins to leak the pressure in the line once the bottle was closed, I didn't want that unmetered n2o entering the engine or risk starting the engine with the bottle open and getting a nasty surprise. I took the intake off to see how bad the leak was, and it seemed significant enough for me to take the box out and see what I could do. I contacted Zex, but since they only warrant their products for one year (not to mention I’m not the original owner) I was SOL.

So today I removed the box and took it apart, exposing the circuitry and solenoids. Below you will find pictures and an explanation of how I plan to fix the leak.

The solenoid removed from the box, with the electromagnetic actuator removed:


The base of the solenoid showing the inlet/outlet ports and orifices:


The top of the solenoid with the plunger assembly installed:


The plunger assembly removed, note the seal in the center which shows decay. After stretching the spring and retesting the solenoid, it still leaked and I determined the leak was coming from the center seal, and not from a lack of spring pressure.


The seal material was made of a hard material, like a mix of paraffin wax and RTV. I cut/pried it out with a sharp x-acto knife, here is the plunger with the seal material removed:


I then refilled the center of the plunger with Permatex Grey RTV (supposed to be the toughest type) and smoothed the top with the x-acto knife:


After waiting about an hour and a half for the RTV to set, I replaced the plunger and the cap and screwed it onto the base so the RTV would conform to the contours of the center orifice:


I then removed the plunger and am allowing it to harden overnight. I will put the solenoid back together tomorrow and test its ability to hold pressure. If I had to do one thing differently, I would have waited longer before reinstalling the plunger. The RTV was still too soft in the middle and it ruptured the surface and clogged the orifice with soft RTV. I managed to clean it all out and think it should still work.

Moral of the story, Zex components suck. This system was barely used. I also found out that Zex does sell replacement solenoids for $42, part numbers: ns6683(n2o) and ns6682(fuel). Buying a replacement will be the next step if this solution doesn’t work. I’ll let yall know how it turns out.

 

Looks like a solid repair but I wouldn't risk it! The worst case scenario is an expensive one if that solenoid flows out of control. Nice creativity though, "if" that plug permanently holds and last the abuse It could work.

 

This.

For $42 bucks, I'd say that's well worth the investment. If your homemade fix doesn't hold up and a piece of it happens to get passed all the way through to the combustion chamber, who knows what could happen.

 

Well, after reassembling the solenoid, I tested it and it held pressure! However, since I am extremely thorough about anything that goes on my car, I decided to take apart the solenoid one more time to inspect the seal and insure everything still looked ok. ….And it’s a good thing I did. Even though it continued to hold pressure after I tested it, I found that the RTV had not completely solidified all the way through even after 24 hours. Because of this, when the high pressure nitrous flowed passed the seal, it caused the liquid RTV to break the surface and compromise the seal. The pictures show the compromised seal.

I finally decided that it’s not worth $40 to possibly destroy my engine if the seal fails and nitrous flows freely into the engine without additional fuel or at sometime other than WOT. So I called up zex and ordered a replacement solenoid that hopefully lasts longer than this one. I am still convinced that if the RTV been given enough time to cure completely, the repair would have held up and been suitable for long term use. Oh well, it was worth a shot.

The two videos below show my functional testing of the repair, followed by pictures of the seal:

 

Nice find I think mine is leaking also. I bought it used also as well. I have a digital gauge so when I close the bottle the pressure should hold in the line, but it doesn't for some reason.

I don't know if it's by design to slowly bleed off. I may just replace both solenoids for piece of mind.

 

if its slowly bleeding off, check all your connections as well, listen for leaks or put water on them and look for bubbles

 

I read this thread, it made me go with a NX express Proton kit instead of zex.


thank you.