Hey ADX36,
I would do a leak down test. You may not want to see the results of that test but it's probably going to tell you the story
Money shift usually always leads to bent valves. Ok compression does not = Ok valves.
Here's an excerpt from a website I found to help explain it for you.
Hope this helps and you get to the cause. Good Luck.
Cheers,
~Ralph
"A compression test measures how much pressure the piston creates in the cylinder when traveling from bottom dead center (BDC) to top dead center (TDC) with the valves closed. The reading is taken at the spark plug fitting in the cylinder head.
Lets say for instance that we have the following compression readings:
1-150, 2-180, 3-140, 4-145
1,3 & 4 are all within the 10% specification but 2 is 20% higher than the average of the other cylinders. Does this mean number three is high or the others are low?
To get to the bottom of this question we need to start by examining the spark plugs. Do they all look the same? Is #2 badly carbon fouled? If you have one or more cylinders with high compression and oil burning, the high compression can be caused by the build-up of carbon on top of the piston.
In our test case, the high compression of #2 cylinder can be caused by excessive carbon build-up on the piston. Now to prove it!
Cylinder leakdown test-
While a compression test is a dynamic test (engine moving), a cylinder leakdown test (C.L.T.) is a static test (engine at rest). The compression test measures how much pressure the engine can produce while cranking; in contrast to the C.L.T., which measures how much pressure is lost in the engine. In a C.L.T. the engine is placed on TDC of the cylinder in question and using a similar type of connector as the compression test, we fill the cylinder with pressure. The tester then measures the volume of air needed to maintain a predetermined pressure in the cylinder. This reading is expressed in a percentage. Good cylinder leakdown readings should be below 5-8%.
The great thing about C.L.T. is that it deals with how well the cylinder is sealing and nothing else. The readings are not affected by carbon deposits, cam timing, or even engine cranking speed.
Another great feature of the C.L.T. is the fact that you can hear where the air is leaking out of the cylinder. When a cylinder has high percentage of leakage, first check the oil filler cap. Do you hear a hissing sound? If so, you may have pressure leaking by the rings. Is there air escaping out the exhaust? Is it escaping out the intake system? Then a burned valve may be the problem. If two adjoining cylinders have similar low readings and you hear leakage out the other cylinder, then a failed head gasket may be the problem.
Being able to pinpoint the exact source of the compression loss will tell you where the problem is; and not just that you have one. This knowledge will greatly assist you in the next step… the repair."
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