Clickety Click
Solenoid Maintenance
by Dave Koehler

One hot day on Manufacturers Row I was consulting with a well known nitrous racer about his tuneup. No name to protect the silly. In the course of things he made the statement that he thought checking and rebuilding his solenoids was a big pain in the exhaust. I was dumfounded. Here was a person who got filthy checking and adjusting his clutch every round. I gave this about a half a lap of thought and responded that he could run a blower and restrip the rotors every lap or so. After he absorbed that idea the solenoids looked pretty easy.

The point to the above story is that the solenoids are indeed a simple device and maintenance on two nitrous solenoids might take five minutes, if that, and you don’t even have to remove it from the car in most cases.

Solenoids are purchased by the nitrous manufacturers from only three or four different solenoid manufacturers. Some are made to the nitrous manufacturers specification and others are off the shelf stuff. Off the shelf solenoids is how all this started many moons ago and still works fine on the smaller HP kits. What the nitrous manufacturers specify to improve the product is inlet and outlet design, sealing material, and coil type and strength. I know of no nitrous manufacturer that actually make their own solenoids in house. There would be no point. Some parts of the solenoid would take hi buck CNC machines and years of experience to make consistently correct. Some manufacturers do spend time and money testing and modifying solenoids in order to make a better product and then have the solenoid people incorporate their idea into the next batch. Hot Rod tinkering never dies!

Regardless of brand, the solenoid consist of eight parts. A base, piston or plunger, seal, spring, upper piston housing, coil, cap, and a nut. Of those eight parts only two actually move! The piston and the spring. How hard can it be? It’s not. So let’s rip one apart.

Remove the nut on the top. The coil cap and coil can now be removed as a unit and laid to the side. You will now see a tall housing that the coil slid over. There are a couple of different designs of these depending on the size of the solenoid. Some baby solenoids used on small kits and purge valves have a slot on the top of the housing. Take a screw driver and remove the housing. The larger solenoids have two holes down at the base end. This requires a spanner wrench to remove. This little wrench is included with the rebuild kit available from your nitrous company or guru. First time and you don’t have a wrench? Don’t despair! Take a second nut from another solenoid and double nut the threads at the top of the stem and remove it.

Now that the housing is loose remove it carefully and note where the spring goes. Some go on the outside of the piston and the little ones usually go on the inside. Anyway, they are easy to drop so watch what you are doing.

Now , DO NOT under any circumstances take a pair of pliers and grab that piston housing. You will find after you get it apart that it is made of thin stainless steel. The slightest tweak will cause the piston to hang closed or open. Picture the solenoid open in your mind at the wrong time. Bad, huh? While on the subject of damaging the housing, when installing the pipe fittings on the inlet and outlet DO NOT hold the solenoid by the coil when tightening. It takes very little force to tweak that housing! Hold the solenoid by the base. When you get your rebuild kit, keep the little spanner wrench in a safe place. Nuff said?

You now have the piston, spring, and seal in your hand. Take a look at the end of the piston. You will see that it seals against the base on a raised ring. The combination of the raised sealing ring and pressure will leave a dent in the sealing material on the piston. At this point we will assume we have normal wear and the system is running OK and if you get your spark plug lite out you will see that the sealing ring leaves a depressed rings on the seal material. The overall shape of the material should still be relatively flat. If you see rips, chunks, or ground in junk it’s time for a change. I will get into abnormal damage and problems in a later article. For now we will assume you see some chunks missing and opt to put a new piston in.

While you inspecting take a look in the base for junk. If you see any you have a serious rust/junk problem somewhere between the tank and the solenoid. Clean it out. Somewhere in the system you should have a filter to knock this problem down. Some systems have a little screen on the inlet fitting. Remove the hose and take a look in there. See junk? Fix it. If your system is apart and laying around the shop, be sure and blow out the hoses, etc. before reassembling. The point is that junk in the nitrous side does two things. It slows down the volume of nitrous to the system and makes it rich or if it gets by the filter it can lock the solenoid open. Neither of which make for a happy day.

Speaking of junk in the system. This can start as far back as the filling station. I had a customer that complained that the car was slower and slower even though he kept increasing the nitrous jet AND the nitrous pressure. This got so far beyond any normal tuneup that I pictured a mushroom cloud on the horizon and had him send me the solenoids for inspection. I assumed the piston was damaged but when I opened the package, great gobs of rust fell out. Hmmm. The solenoids were packed almost solid with rust and the pistons jammed open. The solenoids had screens on the inlet fitting but they had been blown out by the rust creating a solid stop and the hydraulic effect of extreme hi pressure nitrous. The good news is this got corrected before the engine croaked. The moral of this story is that your filling station needs a filter. If your nitrous filler doesn’t have a filter, buy him one.

OK, now that everything is cleaned let’s put the new piston back in. Install the new seal down in the base cavity. Use NO oil. Install the spring on or in the piston and slide it in the housing. Move it up and down a couple of times and see that it moves freely. On the piston style with the internal spring, make sure it’s in the right spot. It’s possible to slide it in there and not have it in the pocket. The result is the solenoid will not open, regardless of pressure. Now screw the complete upper housing with the piston back onto the base. This does not need killer torqued so don’t let the resident gorilla on the crew do it. It is a solid metal to metal stop. Slide the coil and cap back on and install the retaining nut. Here again, no extreme torque is necessary. Give it a dry click test. Nitrous solenoids have a crisp, fairly loud snap sound, while fuel solenoids are much quieter. Congratulations, you have successfully "restripped" your blower!




I fixed mine some how, I sprayed some w-d in it, turned it upside down and clicked it a few times and something fell out of the "in" side . I clean all w-d out and it worked fine @ 1000psi.. Its fixed for now.

 

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