[PS2N54]

got some unexpected compression results on a 125k n54 motor that for last 20k miles has been neglected by previous owner/s. i tested using 2 different brand gauges just to be sure.

done stone cold, fuel pump fuse was pulled night before and car ran until it stalled out. test at 230ft above sea level on a cool crisp day.

iam not complaining at the results, was expecting in 150-160 range given visual state of things, unless carbon and sludge is whats sealing this engine

iam pulling this motor to do a refresh, almost considered getting another lower mileage motor so i wouldnt have to do piston rings, but with these results i will just refresh the gaskets/seals/rodbearings/pulleys and clean valves + seals for now.

CYL 1: 182 PSI (first run was almost 190PSI due to possible fuel vapor)
CYL 2: 180 PSI
CYL 3: 180 PSI (first run was 172 PSI due to car battery getting low)
CYL 4: 177 PSI
CYL 5: 175 PSI
CYL 6: 180 PSI


pics are of first run, i redid everything using another gauge to verify but didnt take photo.

[whyzee125]

Excellent results! Keep in mind consistency is more important than high numbers but you’ve got both here. N54s are very stout engines.

[Dave92N54]

Not surprised one bit. My 130k tested 180 across the board. As long as it wasn't completely abused, or someone let a leaky injector wreak havoc, should be pretty good.

[PS2N54]

very reassuring to hear this... i have much less anxiety now over everything iam gathering to do on the car.

thanks for mentioning leaky injector part, did not know it would create massive damage that would lower compression. iam already suspecting the injectors are no good on the car, they are Index8 and two are replaced with index12 by previous owner on Cyl2 and Cyl5.

Iam also pretty sure Cyl3 injector is either leaking or sparkplug no good, since its only cylinder that i can smell fresh gasoline on the tip of sparkplug. (i already tried swapping coil with one from my other car that i know is good, same result)

[Dave92N54]

Originally Posted by nzero

very reassuring to hear this... i have much less anxiety now over everything iam gathering to do on the car.

thanks for mentioning leaky injector part, did not know it would create massive damage that would lower compression. iam already suspecting the injectors are no good on the car, they are Index8 and two are replaced with index12 by previous owner on Cyl2 and Cyl5.

Iam also pretty sure Cyl3 injector is either leaking or sparkplug no good, since its only cylinder that i can smell fresh gasoline on the tip of sparkplug. (i already tried swapping coil with one from my other car that i know is good, same result)

What happens is the injectors leak and the fuel sits in the cylinder where it makes it's way into the oil. This can wash individual cylinders and ruin your oil.