low compressions
 

1986 190e- 16v

starting from the front of the car to the rear my compressions read 75 / 10 / 120 / 120. The car has been runing like this for a while now I've just found out because I took the car to the shop for a fuel pump change. My symptoms are hard starting and fluctuating Idle. Was wanting some suggestions on what could be the problem and the cost$$ to fix. Is it the rings or the valves?? or something else.

You will need more information than compression readings to diagnose. If it were in my shop, I would do a leak down test on one and two and listen for the escaping air. If from exhaust, it's an exhaust valve, if through intake it is an intake valve. If heard through the oil filler it is a cylinder issue.

The above is under normal circumstances. Since you have low compression in two adjacent cylinders, I would also listen through the spark plug hole of the adjacent cylinders while pressurizing it's neighbor.

Even after all that is done, it will require exploratory surgery.

My $0.02,

it is amazing it runs with such low figures.

tom w