My 1983 300d has roughly 12-15 in/Hg of vacuum at idle. It fluctuates very very rapidly between 12 and 15 on the gauge. Does this mean that the check valve and the vacuum pump are bad? When you rev the engine up to 2000-2500 rpms, I get around 20-22 in/Hg and it still fluctuates very rapidly. I am checking the vacuum at the main servo line that runs to the brake booster. Any insight would be greatly appreciated bcs the price of these parts is defintely not cheap. Thanks for the help!!!!!!
GLIDEHM