Vacuum system troubles, any tips?
07-09-2024, 10:08 PM
#1
Junior Member
Thread Starter
Vacuum system troubles, any tips?
Greetings all, I've been on and off working on getting a 1997 C230 to reliable daily driver condition for the past few months. I've been trying to trace what seems like a leak in my vacuum system.
The first issue I found was the central locking not functioning at all either with the key fob or the button on the center dash. I first checked all fuses and ensured they hadn't popped (specifically fuse no.27 in my case) and found all to be just fine. Next, I located a few vacuum lines with the help of some forum posts to find that many were dry rotted/cracking, which was to be expected given the car is 27 years old, so I replaced those. Specifically I replaced the rubber fitting that connects the white vacuum line to the nipple on the back of the intake manifold, the line from the Secondary Air Valve to the Air Switching Valve, and then lastly the fitting on the Fuel Pressure Regulator. Whatever I did seemed to somewhat aid the central locks, however they function slowly/weakly, and the driver's rear lock doesn't function at all, could this be caused by a leak in that door or a general leak in the system? I haven't had the chance to take the door panel off to see for myself. Adding to that, locking and unlocking the doors from the center dash results in a prolonged humming coming from the pump in the trunk on the passenger side. From what I understand, this is also indicative of a leak in the system.
Secondly, my rear folding headrests also do not function at all. When pressing the switch on the dash, I can hear an audible *click* coming from the package tray area. I also understand they only work when the engine is running. I've tried pressing the switch multiple times in quick succession, holding it down for a few seconds, and pressing/holding it while having someone push on them. None of these solutions worked, so I took a look at the lines going to the folding mechanisms from inside the trunk (which are a PITA to see and get to by the way) and they all looked fine. So I'm honestly at a loss for what could be causing this issue.
I have some time over the next few days to get my hands dirty with this car so any info is greatly appreciated, I'll update this thread with what I try and what works/what doesn't. Thank you in advance.
The first issue I found was the central locking not functioning at all either with the key fob or the button on the center dash. I first checked all fuses and ensured they hadn't popped (specifically fuse no.27 in my case) and found all to be just fine. Next, I located a few vacuum lines with the help of some forum posts to find that many were dry rotted/cracking, which was to be expected given the car is 27 years old, so I replaced those. Specifically I replaced the rubber fitting that connects the white vacuum line to the nipple on the back of the intake manifold, the line from the Secondary Air Valve to the Air Switching Valve, and then lastly the fitting on the Fuel Pressure Regulator. Whatever I did seemed to somewhat aid the central locks, however they function slowly/weakly, and the driver's rear lock doesn't function at all, could this be caused by a leak in that door or a general leak in the system? I haven't had the chance to take the door panel off to see for myself. Adding to that, locking and unlocking the doors from the center dash results in a prolonged humming coming from the pump in the trunk on the passenger side. From what I understand, this is also indicative of a leak in the system.
Secondly, my rear folding headrests also do not function at all. When pressing the switch on the dash, I can hear an audible *click* coming from the package tray area. I also understand they only work when the engine is running. I've tried pressing the switch multiple times in quick succession, holding it down for a few seconds, and pressing/holding it while having someone push on them. None of these solutions worked, so I took a look at the lines going to the folding mechanisms from inside the trunk (which are a PITA to see and get to by the way) and they all looked fine. So I'm honestly at a loss for what could be causing this issue.
I have some time over the next few days to get my hands dirty with this car so any info is greatly appreciated, I'll update this thread with what I try and what works/what doesn't. Thank you in advance.
