Frequently in older cars that have lost compression or power, or in cars in which seemingly serious engine damage has occurred, the tendency is to assume that a new engine is needed.

At Dallas Auto Sports, we prefer to avoid that line of thinking and explore more realistic and certainly from your point of view, more affordable solutions.

As a first step, we typically perform a compression check. A compression check or test is one of the most common methods for determining the mechanical condition of an engine. We usually recommend this diagnostic procedure when we come across an engine miss, rough idle or a wheezing or puffing noise in the induction or exhaust.
We measure the compression pressures of each cylinder with a compression gauge and then compare our readings with the manufacturer's specs for the engine when it was new. A lower than normal reading is an indication that pressure is escaping or leaking from the combustion chamber due to one of these problems:

  • Blown head gasket (head gasket ruptured).

  • Burned valve (face of the valve face has been damaged by combustion heat).

  • Burned valve seat (cylinder head seat damaged by combustion).

  • Loose or worn timing chain which upsets valve timing.

  • Physical engine damage (hole in piston, broken valve, etc.).

  • Valve train problems (valve adjusted with insufficient clearance which keeps the valve from fully closing. Also, broken valve spring, seal, or retainer).

  • Worn rings or cylinders (wear that prevents a ring-to-cylinder seal).

If a compression check reveals that one or more of the cylinders tests low, then a cylinder leak-down test helps us determine the cause of the weak cylinder.
Our test equipment registers the pressure drop indicating the percentage of leak. In addition, if we hear escaping air at the exhaust pipe or air intake system or the oil breather, then one of the components is leaking.
If we hear air at the exhaust pipe it means the exhaust valve is leaking. If we remove the radiator cap and observe bubbles then it’s a good bet it’s a blown head gasket and or a cracked head.
Our point in detailing these various checks is that there are several ways to diagnose and repairing serious engine problems short of complete engine replacement…a process that typically costs several thousand dollars.
For more information about your particular problem, give us a call. We can get much more specific when we hear what your engine is (or isn’t) doing. Or better yet, stop by. Nothing beats looking at the problem first hand.
Dallas Auto Sports 214.320.2228


Auto service and repair for: Audi, BMW, Mercedes, Land Rover, Lexus, Jaguar, Porsche, VW, Volvo, Saab, and more. Servicing cars from the Dallas, Plano, Richardson and the DFW Metroplex area.