Q: Why doesn't anyone offer a quote for a compression or CLT test?

asked by on

Why doesn't anyone offer a quote for a compression or CLT test? These two tests alone will definitively tell you if you have a leak or other engine problem and where it is. Why can I not find these tests available at most mechanic shops or sites, including yourmechanic.com

In almost all cases, individuals with engine faults are seeking resolution to an "acute" fault and not so much presenting with a "worn out" engine, that is one with low cylinder compression and cylinder leakage. A compression loss that is large enough to be meaningful, that is one that causes a misfire, or a large cylinder imbalance, will result in a Diagnostic Trouble Code being set. Modern engines are so mechanically reliable that, in the present OBD-II regime, cylinder misfiring (or other engine "malfunctions") are almost always found in causes that stop well short of the kind of serious mechanical faults that cause "low cylinder compression". Of course, in the OBD-II regime, in any given diagnostic if the common causes of cylinder misfiring are not found in the usual ignition or fuel related causes, compression is checked but such is done nowadays using an electronic tool and so, even that check, has become just an integral part of the overall diagnostic. Due to the negligible "added" cost of performing the electronic test, there is no reason to create a separate service, the service that was formerly known as "compression check". To sum it up, there are a confluence of factors that explain the change you have seen: 1) engines are mechanically reliable, so much so that "loss of compression" is really not the issue it once was when a customer presents with a problem; 2) On board diagnostics, and new electronic diagnostic tools, have changed the nature of diagnostic protocols; and 3) if compression testing is needed the test itself is just subsumed within the overall "engine diagnostic" and no need to bill separately. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Why doesn't anyone offer a quote for a compression or CLT test?

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Master cylinder push rod loose

If the push rod came loose from the clutch pedal, it may be possible that the retaining pin simply slipped out, or the push rod is broken. I would recommend having a professional technician, such as one from YourMechanic, examine...

Q: engine light stays on even after replacing the intake valve selenoid the code is p0075

Diagnostic trouble code P0075 means there is a fault in the Intake Valve Control Solenoid Circuit. A defective solenoid is one possible cause of the code setting but problems in the circuit wiring are often the cause of the fault....

Q: Do you suggest me getting a third opinion from another mechanic?

The odor of something "burning" should be investigated and completely resolved first before any other repairs are attempted. The odor might not be due to the belts and a possibility is oil leaking onto the manifold. Such would be a...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...