Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Correlation between high engine compression, excessive oil pressure and leaking seals?

‘‘Mystic, thanks for the compliment. I just last year retired from a college. I’ve written quite a few college courses, including developing an entire technical degree program in cooperation with other faculty (me being the lead), but not on the subject of automotive. I guess I just developed a knack for explaining things.’’

You’re welcome! And congratulations on your retirement.

‘‘My opinion is that you should be dancing in the street to have that kind of pressure at 185k miles.’’

I am happy with the consistency between the cylinders and the fact that the motor is getting stronger instead of weaker. (If the pressure continues to rise I’m going to have a race car on my hands.:slight_smile: )
It’s just that it seems so much higher than what the manual considers normal but I don’t think it’s anything to worry about anymore after reading this thread.

I already purchased a new CAT a few weeks ago. I’m fairly certain the one on the car is no good because I tested the O2 sensors with a scan tool. The front and rear sensors were basically showing the same readings so I don’t think the CAT is doing anything. And the computer is sending a P0421.
I’m pretty sure a misfire did it in due to me not plugging a spark plug wire all the way into the distributor cap. By the time I found out why the engine light was flashing the copper/brass on the plug wire had turned a blue-green color due to arcing. I bet enough unburnt fuel made it to the CAT to ruin it.

I do have a vacuum gauge. Never used it before but I’m willing to give it a shot. I’ll report back after I figure out how to use it and get some readings.


It certainly sounds like you fried the cat

I’ve seen severe misfires plug a cat completely within 5 minutes