Hello, unfortunately Ford does not give specific specs on compression, they only give a variation of 25% from cylinder to cylinder. So according to that, you're within spec. and I know that's a terrible way to do things, but 130 is getting low. But you have to consider the age of the truck. You can listen to the cranking cadence, I believe a truck that age has clear flood mode, if you push the gas pedal to the floor it should shut down the injectors and you can listen to just the engine cranking. It should be a nice even sound, if you notice any dropouts during cranking, which can be a broken valve spring, a sticking valve, etc. But compression around 170 would be good for a newer truck. If you're worried about the compression and want to determine where the issue might be, since you're doing a static compression test, not running, put a little shot of oil in the cylinder and redo the test. if compression comes up, you know it's the rings or pistons that are worn. If it stays the same, then most likely it's something to do with the upper end components.
Just a side note. If you do not unplug the fuel injectors during the test, fuel will wash the cylinder walls down and you will have lower compression due to that, so if you start the truck, let it run for a few minutes and then unplug the injectors and retest, you may find higher compression readings.
https://www.2carpros.com/articles/how-to-test-engine-compression
https://www.2carpros.com/articles/the-reasons-for-low-compression
Jul 12, 2022 at 8:44 AM
