Mercedes 1986 300E 165,000 miles
I have a 1986 300E with 137,000 miles. I recently changed the black hoses (both sides) of the Idle Control Valve, my original ones were showing signs of cracks. When removing the original hoses, hose that goes from the ICV to the throttle bonnet (rubber part between the fuel distributor to throttle valve) I noticed oil inside the hoses. is this normal? If not, why is there oil in the hose?