Re: 1957 FD11 Johnson questions

[chinewalker]

Unless something is inside the cylinder and hitting the valve to release the pressure, I say it’s a gauge issue. I suspect you’ll also get higher readings if you pull the lower unit off, releiving any friction from the impeller. I had a 9.5hp low boy that I had installed a Sierra about two years ago. It swelled quite a bit and made the motor very difficult to pull over. Easiest thing to check and inexpensive to replace if needed.