Why Does My Injector Seal Leak?

That can be a tough question. But, you had better find the answer, or the repair process can be much more difficult than it needs to be. When you fail to get a good seal between the injector and the windshield, each pressure and vacuum cycle is less effective. A leaking injector seal can lead to increased repair time, excess resin waste, and worst of all, inferior repairs. Many technicians that I talk to assume it is normal for resin to leak between the end seal and the glass. It isn’t. If your injector seal leaks regularly, there is definitely a problem somewhere, so let’s find it.

Do you level your bridge properly? Pay special attention as you are initially setting your bridge over the damage. Once the injector touches the glass, make sure to add at least ½ turn to create a good seal. You don’t want too much pressure against the glass, but you need enough to keep the injector from leaking. Another mistake many technicians make is bringing the back legs down until they just touch the glass and calling it good. Don’t do this. Bring the back legs down until they touch and then give them each at least a full 1 and ½ turns. By adding pressure from the back of the bridge you are creating a much more even pressure all the way around the seal, which will minimize leaking.

Is all the air out of your suction cup? If you are using the B300 bridge with the pump style vacuum cup, you need to be sure the suction cup is completely seated against the glass and is very stable. The red line on the pump is a good guide, but make sure to check the cup itself very closely. If one side is higher than the other or you see a “bump” on one side, keep pumping. A sloppy suction cup can lift away from the glass a little too much, which will increase the likelihood that your injector will leak.

How often do you change out your end seal? I talk with technicians that are trying to get 40-50 repairs out of a seal. To put it bluntly, you can’t do consistently great repairs unless you are changing your seals regularly. I recommend changing your seals every 10-20 repairs. An old seal is much more likely to leak than a new one, but that is just one reason to change your seal regularly. After 10-15 repairs the walls of the seal are broken down enough to allow some resin to blow past the piston and up into the injector while you are applying pressure to the repair. When this happens, even though the seal is not visibly leaking, your pressure and vacuum cycles will be less effective.

How far down do you push the injector on the pressure cycle? It is important to push the injector piston down into the end seal during the pressure cycle, but don’t over do it. Push the injector about half way into the seal. Use your inspection mirror to watch the seal carefully. As you push the injector down you will see the walls of the seal begin to bow under the pressure. When you see this happen, stop pushing. Never push the injector all the way down.

Are you using two hands? That’s right; windshield repair is just like baseball. Ok, maybe not just like it, but it is important to use both hands when you catch a fly ball and when you put your injector in the vacuum or pressure positions. I see too many technicians pull up on the piston with one hand to put their injector in the vacuum position. If you don’t brace the bridge with your other hand you could very likely pull the injector away from the glass and break your seal.

Are you lining up your injector over the damage carefully? Use your inspection mirror to make sure your injector is centered exactly over the impact point. Our new inspection mirrors are magnified 3X to make it a lot easier to see just what is going on under that seal. If you don’t have a mirror, make sure you check from inside the vehicle.

So, if you are having trouble with a leaking injector, pay attention to the details. It will save you a lot of time and trouble. If you still have trouble, make sure to give us a call for technical support.

-Matt Larson