what is the compression suposed to be on a 1983 jeep cj7 258 straight 6 cylender

Asked by Apr 20, 2012 at 08:19 PM about the 1983 Jeep CJ7

Question type: Maintenance & Repair

1 Answer


You should get around 139 psi. More importantly is that they are all very close in pressure. If they are all within 10% of each other that is best. If you really want to get a good indication of the condition of your engine and its components the vacuum check is the best. Get yourself a vacuum gauge and hook it up to manifold vacuum........ Here is a good reference for vacuum trouble shooting.......... You should get between 17-22 in. hg. depending on your elevation above 2000 feet MSL or mean sea level. To perform this test hook vacuum gauge directly to manifold vacuum. 1. Low steady needle usually indicates leaky intake, a leaky vacuum hose, late timing, or incorrect camshaft timing. 2. If reading is 3-8 inches low and fluctuates at that low reading suspect an intake manifold gasket leak at intake port or faulty injector. 3. If the needle has regular drops of about 2-4 in hg. at a steady rate the valves are probably leaking. (Perform a compression check). 4. An irregular drop or down flick of the needle can be caused by a sticking valve or an ignition misfire. 5. A rapid vibration of about four in hg. indicates worn valve guides. 6. Slight fluctuation of one inch or so indicates ignition problems. 7. Large fluctuation perform a compression check. 8. If needle moves slowly through a wide range check for PCV issues.

1 of 1 people found this helpful.

Your Answer

Jeep CJ7 Experts

  • #1
  • #1
    Randy King
  • #3
View All

Related Models For Sale

Used Jeep CJ5
32 listings
Used Jeep CJ8
9 listings
Used Ford F-150
2,558 Great Deals out of 220,223 listings starting at $1,222
Used Ford Bronco
208 listings
Used Jeep Cherokee
281 Great Deals out of 65,085 listings starting at $2,995
Used Chevrolet Camaro
242 Great Deals out of 30,118 listings starting at $4,980
Used Jeep Wagoneer
10 listings
Used Ford Mustang
291 Great Deals out of 38,369 listings starting at $1,995

Used Cars For Sale

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.