In this video we’ll replace the actuator on a VNT-15. While installing the new actuator, we will use a MityVac to calibrate.
In this video I’m going to replace and calibrate the actuator on this VNT 15 turbo. This turbo is obviously out of the car—we’ve got it out of the car so you can see what we’re doing, but you can do this with the turbo on the car as well. This procedure for replacing the actuator is the same for a VNT 17 or VNT 17/22 hybrid.
First thing we’ll need to do is take a flathead screwdriver or a pick tool in order to remove the circlet that holds the end of the actuator to the turbocharger vein lever.
The next thing we need to do is remove the two 10mm nuts that hold the actuator to the bracket. With the nuts out of the way, we can slide the actuator off.
We have the old heat shield here that we took off the old actuator, and we need to put it on the new one before we replace the actuator. You’ll find a small vent hole that’s going to be protected by the shield. Simply line it up and slide it on. You also want to be sure that the lock nut and adjusting screw is loose and easy to turn, because it will be more difficult to turn when we have the actuator attached to the turbo.
Now we’re going to put the actuator on. When we do this, we’re going to want to line up the brack with the exhaust side of the turbo—the bracket acts as a heat shield. First thing we want to do is catch the arm of the actuator on the vein lever; and second line up the two studs. Next, catch the nuts so the actuator doesn’t fall off. Now, add the circlet here. Tighten up the nuts.
Alright, with the actuator attached, we’ll adjust the actuator with a MityVac. We haven’t tightened down this nut, because we’ll be using it to adjust the actuator. Attach the MityVac to the actuator and begin pumping. What we’re looking for is to see when the actuator starts moving, and how much pressure it needs to reach the actuator stop. On this turbocharger we’ve noticed that while it moves initially, we can’t get it touch the stop. This means it’s too long. If you want the actuator to touch the stop earlier, you need to shorten the actuator. If you want it to touch the stop later, you need to lengthen the actuator. This translates to boost for your car as well. If your car is underboosting, you need to shorten the actuator. If it’s overboosting, you need to lengthen the actuator. We’ll loosen the locknut and rotate the lever to shorten this actuator rod. One or two threads can make a big difference, so it’s better to check before you go too far.
That’s pretty close to perfect. We’re going to take one more thread out and test it one more time. 18 inches of mercury it hit the stop, which is great. Anywhere between 15-18 inches of mercury should have the rod fully extended, and the rod should start moving at around 3-5 inches. Once the adjustment is set, just tighten the locknut.