I have a 1971 ford maverick grabber, 250, 4.1 L straight six. I have been told that cylinders 1-5 are 150 psi but 6 is 95 psi. My question is does it need to be fixed asap or can it wait, I don't drive it a lot due to work and weather, may only do 600 miles a year, plus what should or be the best psi for the motor.
It probably has a leaking exhaust valve, which will get worse but at most means it needs new valve(s) when repaired... If the head gasket were leaking it would likely be pushing out coolant, so guessing that's OK... Worst case is a cracked/damaged piston or rings... While not nearly as common as valve problems, this condition can damage the block if repairs are put off too long... Most of the time there would be some noise associated with this condition...
If it still runs well (Smooth) Isn't oil fouling the spark plug on the weak cyl. Drive it and enjoy...Its an exhaust valve...It will get worse over time though. So keep an eye on it. check oil level regularly. Dont beat on it though. It will fail sooner that way. Plan for a proper leak down test soon, and a valve job in the not to distant future. Good luck!!
