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How To Rebuild A Nitrous Solenoid

By: Jeremy Stoermer12/14/2018 < Back to Blog Home

No one wants to lose a race because of a failed or temperamental nitrous solenoid? Whether you’re a hands-on kind of person, or just want to save some money, Nitrous oxide systems have rebuild kits and factory replacement coils to make your nitrous and fuel solenoids perform like new.


Testing, cleaning and rebuilding your nitrous or fuel solenoids is an easy process that most anyone can master. Solenoids use an electro-magnetic coil to overcome spring pressures and pull up on a plunger. This plunger either blocks (closed position) or allows (open position) the flow of nitrous through passages in the base and into the intake of your engine.


To begin this rebuild process first, disconnect the vehicles battery power and shut off the nitrous supply at the bottle, then empty any remaining nitrous from the lines. You don’t have to remove the solenoid from the system but it does make the whole process a little easier, especially if the solenoid is in a hard to reach area. Simply loosen and remove the lines or fittings then remove the solenoid from the mounting bracket.


To make the disassembly process easier you can secure the base of the solenoid in a vise, but be careful not to damage the port threads.  Using a pair of soft jaws or some plugs or old fittings in the ports will protect the threads from damage and keep you from marring the housing with the vise jaws.


Begin the disassembly process by removing the nut on the top of the solenoid. You can use the supplied wrench or a ¾” wrench or even a Cresent wrench to do this. Slip the coil and coil cover off and inspect for damage to the coil or coil wires.


Using the included spanner wrench engage the 2 holes in the base then loosen in a counter clockwise rotation, removing the stem from the solenoid base. Never try to loosen by clamping or grabbing the stem!


Be cautious when you remove the stem. The plunger or sometimes called a piston and the spring will need to be installed correctly in order to ensure proper operation. Remove and closely examine the plunger. The plunger sealing surface is critical for proper operation and should be flat, free from crowning, deep indentations and any debris. If the plunger surface is damaged, discard and replace the components with a service kit from NOS.


We have a large selection of service kits available for most nitrous and fuel solenoids on our website. Use a pick to remove the base o-ring and replace it with the new one provided in your kit. While you’re here check for any small screens in the port leading to the jet for debris or blockages. Remove any debris from the screen with a shot of brake cleaner and let air dry. 


Clean, dry, and inspect the solenoid stem and base then reassemble in the correct order with the new plunger and spring found in your kit and tighten hand-tight with the spanner wrench.

If you suspect you have a faulty coil, you can replace the coil assembly with a new unit from our full line of solenoid service parts.


Begin by pulling the 2 wires out of the grommet found in the coil cover.  Feed the leads from the new coil back through the cover in the same direction. Applying some vaseline to the wires will help you with the process, now press the coil into the cap while gently pulling on the leads. Reinstall the coil onto the stem and secure it with the nut and hand tighten.


The whole process is identical for our NOS fuel solenoids but remember, nitrous and fuel solenoids cannot be interchanged due to pressure differences between the systems.


You can now re-install your rebuild solenoid in your system. Don’t forget to test and purge your nitrous system to ensure that any debris that may have found its way in, is cleared before final use.


Thanks to Nitrous Oxide Systems, a little elbow grease and a few minutes of your time is all that’s needed to have that solenoid functioning like brand new, at a fraction of the cost!


To find a service kit or replacement coil for your Nitrous or fuel solenoid visit our website at NOS nitrous.com.

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