Valve seats

Tiny
PEDRO BLANCH
  • MEMBER
  • 2000 FORD FOCUS
  • 2.0L
  • 4 CYL
  • AUTOMATIC
  • 174,000 MILES
I took the car to a mechanic and he ran a diagnostic check. One cylinder showed no compression. The car was running by that time but rough and the check engine light on. Now it stopped and I want to know what is best.
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Thursday, June 1st, 2017 AT 10:39 AM

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Tiny
STEVE W.
  • EXPERT
No compression can be caused by a few things, Bad head gasket, damaged valves/valve seats being the common ones. Using a leak down tester to pressurize the cylinder while it is locked at top dead center on the compression stroke would tell you a lot. For instance if you apply air pressure and hear air blowing out the exhaust you have an exhaust valve problem. If you start seeing bubbles in the coolant reservoir it is a bad head gasket. Air out the intake = bad intake valve. Now let's say you do not hear air in those spots, remove the oil fill cap and listen there. In this case there will be a bit of air as the piston rings do not seal perfectly, but if you can hear it very loud you have either a damaged piston or piston ring problems.

From there you can decide how to proceed. If it is the valves the head has to come off and either be replaced or repaired depending on the actual issue. If it's in the lower end I would probably opt for a used engine being it is a seventeen year old vehicle.

The larger question being, is the body in good shape, interior, running gear. Engine repair could cost more than a replacement vehicle in some cases.
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Thursday, June 1st, 2017 AT 4:07 PM

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