A few weeks ago on my way back from Nashville, I began to hear an odd noise from the car. I was running about 90mph and it sounded like the whine you'd expect to hear from the differential in a big dump truck, but there was no dump truck nearby. After varying my speed and engine RPM, I realized it was coming from my car. I made a rest stop and could hear it coming from the engine. It was a sort of a whining/whirring noise, and I could feel some vibration in the steering wheel and pedals. These are pretty much tell-tale symptoms of a failing pulsation dampener. Further testing confirmed it. It won't make any noise until the fluid heats up. A single short drive of 5-10 miles with RPMs kept low would not create any noise, but the moment I revved beyond about 3,000RPM, I'd begin to hear and feel it. Or, after driving a bit and then stopping, I'd then hear the noise on the next drive. My theory is that there is a pinhole in the diaphragm and cold oil is too thick to enter it, but once it heats up, the oil thins and the pinhole expands, and it fills with oil and stops working.
Since my car has the MY2007+ ABC system, the pulsation dampener is mounted directly to the pump. WIS states that the pump must be completely removed for replacement. Part of this is for access, because the dampener is wedged in under the head cover, but also because the dampener is only to be removed with the pump upside down to prevent any contaminates entering the pump. I decided to take my chances and just clean everything thoroughly and remove the dampener after detaching the pump from the engine and sliding it forward. I took one photo (below) of the pump moved forward with easy access to the dampener.
To do this, I had to remove the serpentine belt, the pulley on the pump (to access one of the bolts) and the three bolts holding the pump to the engine. I also unbolted the pressure hose from its bracket to make access easier. The pump was easy to move forward enough for the pulsation damper the be accessed.
Here are the steps I took:
1. Lifted the front end and removed front left wheel (just for easier access for crawling under the car) and the lower engine paneling.
2. Released the belt tensioner from underneath the car and locked it in place with a small screwdriver.
3. Removed the bolt holding the pump bracket to the engine block. I decided to remove the bracket form the block rather then bracket from the pump as access was easier.
4. Back up top, I removed the serpentine belt from the ABC pump and AC compressor.
5. Disconnected the wiring harness from the ABC pump and move it out of the way.
5. Removed the top bolt holding the pump to the engine (actually it bolts onto the timing chain cover).
6. Discovered that even with some of my low-profile tools, I could not get to the lower front bolt without removing the pump pulley.
7. Removed the three bolts holding the pulley to the pump. Note that this would have been easier with the serpentine belt in place to hold the pulley, so do that first!
8. With the pump loose, I could slide it forward just enough so the pulsation dampener was clearly accessible (see photo below).
9. THOROUGHLY cleaned the area on top of the pump and around the dampener. I first hosed it down with a can of electrical contact cleaner. I figured that would be better than engine degreaser as it dries quickly. I used a microfiber cloth wrapped around the dampener and "buffed" it.
10. I replaced the dampener and put everything back together.
11. I found it easier to first install the top front pump bolt without the hose bracket to hold it in place. Then, i was able to get the lower bolt and bracket started, the rear bolt started, and then torque everything down.
12. I was able to hold the pulley with my hand when torquing its bolts.
The torque for the pulley bolts is 30Nm, the pump-to-engine bolts are 20Nm. The pulsation dampener is 45Nm.