Hello fellow benz fanatics. I owned a 76 300D in high school, but couldn’t afford to keep it. If this forum was around back then, I sure missed out – What a terrific resource!!

My passion never died, I am now the proud new owner of a 1980 280E. The car was a terrific deal, but on the down side, I purchased it from a dealer, who of course didn’t know, or didn’t disclose the history of the car. I have spent many hours learning more about my car by reading threads on this forum; however, I still have a number of questions. I am certain that at least two of the problems below are interrelated, but I’m not sure which ones they are. I would greatly appreciate help putting this puzzle together:

1) I have a vacuum leak - How does a leak in the vacuum system lead to poor engine performance, and how much performance can be lost? I did a compression test, and found that all 6 cylinders had compression between 95psi and 115psi. I found a thread that referred to normal compression in the M110 engine as 175psi-185psi. I did the teaspoon of oil down there sparkplug well test, and that brought the compression to 125psi. Do I have worn rings, or could the vacuum account for compression as low as 95psi?

2) My car barely runs when I first start it due to a loping idle (when I hold the gas down, it takes about 4 seconds for the engine to respond at all, at then the revs go through the roof) After I let it warm up a little, the idle levels off, but when I push the gas to the floor, the car barely moves, until it has warmed up even more. The dealer did say something about the warm-up regulator being faulty. Could this problem be attributed to the vacuum leak, or a faulty warm-up regulator.

2) I do have a vacuum line leaving the #6 intake manifold, but there is a hole right beside it (closer to the front of the car). I imagine something should go in this hole, such as a vacuum line, or a sensor. Does anybody know what it is, and if it is a vacuum line, where it goes? The vacuum line going to the FD is capped with a screw, so my guess is that this line should go to the hole in the #6 intake manifold.

3) After driving 100 miles at 75mph, I stopped my car at a gas station and found a huge puddle of oil under the car. Upon closer investigation, I found the oil had come from the crankcase ventilation hose (because my air filter housing was full or oil, and it was leaking out the air filter housing drain plugs).

4) Also, after the engine reaches normal operating temperature, and I turn the car off, there is a pressure release sound coming from the area around the exhaust manifolds. This hissing sound occurs every of couple of minutes, and stops after all the pressure (the manifold, or vacuum lines?) dissipates. Could this be related to the vacuum, or low compression problem, or could it be a blown head gasket?

5) One of the hoses leaving the charcoal canister is corked.

Any information would be greatly appreciated!!