hey guys i did a compression test to my 94z motor just for the heck of it i was in school and i had really nothing to do so i did a compression test the results from one side bank, driver side which is easy to get to was 175 i dont remember what the prefix was but the needle went to 175. Now what do i get out of a compression test, what does that say about my motor? thankx ya

 

I'm not so sure. If it's 175psi, that's rather high.

If it's 175kPa, it's rather low.

Remember the scales next time.

 

Per the FSM:
All cylinders should be above 100 PSI, no cylinder should be less than 70â„… of the highest cylinders.

Diagnosis:
Normal – Compression builds up quickly and evenly on each cylinder. Go through 4 or 5 compression strokes, and use the same amount of strokes on each cylinder.

Bad Rings – Compression is low on first stroke and builds up slowly, never reaching normal. Compression improves markedly when oil is squirted into the cylinder.

Bad Valves – Compression is low on first stroke and does not increase during following strokes. Squirting oil in cylinder shows little improvement.

Bad head gasket – Leaking head gaskets give nearly the same results as bad valves, with the addition of coolant in the crankcase, and/or combustion gases in engine coolant. Leakage between two adjacent cylinders shows as low compression on both cylinders.

In most cases the readings ofa well broken in engine with stock camshaft will range in the order 150-180 PSI. Depending on how fast the starter and battery can make the engine spin, and how many compression strokes before the final reading. However; the actual reading is not as important as the differences between cylinders.

 

Okay. My apologies. I'm sure the scale was in psi. I've done a number of compression tests, none of them on LT1 or LS1s. 175psi seemed high compared to engines that I've actually performed the test on. But yes, the test you did shows a normal cylinder compression. Test all of them whenever you have more time to kill :P

 

thanks ya for your fast response, and thanks alot for your big explanation of what a compression test does thanks pete. all of you guys. thanks and yeah when i have more time i'll do the driver passanger side and driver side all at the same time.