2001 Vacuum readings check... could use your input

https://www.instagram.com/p/BfT02gdlMnH/?taken-by=ericmossy

Instagram video posted above if you can see it.

2001 Jeep Cherokee XJ, 164K miles, auto, 4x4. Hooked up Vacuum gauge to see how healthy my motor is. When it was 1st fired up the needle would skip from 15# to 12# then back to 15#... did that for about 30 sec before it held steady at 15#. When revving the engine the needle slipped to 12# then up to ~ 17-18# steady then when throttle closed up to 20# and back to a steady 15#. I think 15# reading is lower than it should be ... what are your thoughts?

I hooked the gauge up via a T section off the side of the manifold. Previously when I checked my vacuum I just pulled the larger Brake Booster line and plugged in my vacuum gauge and the vacuum read a steady 17#'s. Could it simply be the different locations have different vacuums? I don't think so but thought I'd ask. Also when I did this previous vacuum check it was over ~40K miles back I believe... so around 2 plus years.

I am wondering what relation engine vacuum has to engine health ? I would consider cylinder compression readings and oil pressure to be the measure of health of any engine.

Vacuum along with compression can help diagnose engine health or problems before pulling it apart. ����

I have owned a vacuum gauge since auto shop, close to fifty years ago, and it has been used a lot more often than a compression gauge.
I can still remember the shop instructor demonstrating how to used it as a diagnostic tool.
It's as useful today as it was in the previous century.
https://www.motor.com/magazine-summary/mastering-the-basics-reading-a-vacuum-gauge/

17-lbs of vacuum is similar to a the stock 4.0s I've checked.

lazyxj said:

17-lbs of vacuum is similar to a the stock 4.0s I've checked.

Click to expand...

Thanks... so running about 15.5-lbs is a bit on the low side is my assumption? Possibly just a sign of a worn down engine? I do have 164K miles on this one and the 0331 Cylinder head was changed at about 121K miles... so could busted head combined w/ some coolant on bearings and just day to day wear and tear could be the causes of the lowish vacuum readings I'm guessing.

I've actually been considering running some Engine Restore in my 4.0 just to see what the results might be but I normally don't like putting this type of stuff in my engines. I know it has good reviews and proven results but ... I hate to just give my old 4.0 problems.