grx8br

Hi everyone!

I just had a compression test done at my local Mazda dealer and got some results i can't really wrap my head around. The readings were taken at sea level and read directly off the OEM Mazda compression tester and not through the USB.

Front rotor @ 182rpm
5.3
5.6
6.1
x 100 kPa

Rear rotor @ 184rpm
6.0
6.0
5.9
x 100 kPa

Rear rotor as far as i can tell is doing good however the front is looking a little worse for wear. However this test was done with a bad battery and probably a gen 1 starter witnessed by the very low crank rpms.
The car starts right up cold and only takes a bit longer while warm with the same battery and starter. Uses normal amounts of gas. And objectively has great power. Engine was replaced with a Mazda reman 31k miles ago.

Is there a possibility that the results are skewed to look worse than they are or is my relatively fresh engine dead already?

200.mph

iTrader: (9)

the compression #s should be adjusted for the 250rpm cranking iirc

grx8br

When normalized to 250 rpms with the foxed.ca calculator the readings are still not in my favor. However i still wonder if the low crank rpms may have impacted the readings in such a way that the numbers are useless? I cant find many posts about people having their tests done at low crank rpms. I would do another test with a fresh battery but the test is quite frankly too expensive where i live.

200.mph

iTrader: (9)

if normalized and the #s are still below the threshold its most likely low comp. 31k isnt unheard of for an engine to crap out. was it a reman? if not who rebuilt it? what parts were replaced? housings?

grx8br

Well now im sad

Was really hoping the numbers were skewed because of how healthy the engine seems in general. I actually took a compression test to confirm how good it was but it turned out to be the opposite.

Loki

iTrader: (1)

So it sounds like you don't have any actual problems?
I'd put the upgraded starter model on it l and continue enjoying. Maybe retest in some while.

Not that you shouldn't trust the results but like anything, there can be outliers. I had 1 comp test show failing in 2014 and not ever since then.

jcbrx8

Your compression #s appear fine ...after 30k+ mi. and viewed wrt rpm. If difficulty starting as has been recommended... upgrade your starter, and, if you don't already, premix.

Happy rotarying.
.

grx8br

Sounds like i should just disregard the numbers and just enjoy the car while it lasts
I think i'm going to do that.