Compression Test Results

[blackace]

I just did a compression check on my 318.

1 - 116
2 - 145
3 - 140
4 - 140
5 - 135
6 - 133
7 - 122
8 - 120

Now I have an issue with cylinder 8. When I did the test I was not getting a reading. Then after about the 3rd or 4th crank I would get a reading. Not steadily going up like the other cylinders.

What do you think??

 

[Mrmopartech]

If compression is more than 15%-20% lower than the spec required by the factory spec you have a problem,weather minor or major.I would do a leak down test with the proper guage set and determine weather valve seats or rings are leaking on each cylinder.A wet test helps to determine ring problems and small amounts of valves not seating.The wet test should go up a noticable amount when cranked over.This is a ring problem,if only a small amount is gained,the valve seats and face are at fault.You can remove the plugs and put 4 oz of combustion cleaner in each cylinder and leave it over night to help disolve carboned rings that are sticking,weather be compression or oil rings.Mrmopartech

 

[moper]

You have an issue with #1 too. Overall, you should have varience of around 10%, maybe a little more on a high miles engine. If it doesnt develop it right away, yoiu definately have a problem there. Like MrM said..do another test, and squirt some oil in the holes. If they all go up the same, no big deal..If one rises much more than another, you have ring issues. A leakdown test will tell you if it's rings and valves, or just rings or valves, and which valve is leaking.

 

[71_Demon]

What are the factory compression specs for a 318 LA Engine? I did a compression test on my old engine before I pulled it out (cracked blocK) and got about 135 on all cylinders except the cracked ones.

I purchased a remanufactured block and they perform a compression test before packaging it.. the test read 175 psi..

 

[69signetv8]

What are the factory compression specs for a 318 LA Engine? I did a compression test on my old engine before I pulled it out (cracked blocK) and got about 135 on all cylinders except the cracked ones.

I purchased a remanufactured block and they perform a compression test before packaging it.. the test read 175 psi..

Both my MOPAR Bibles says: (318,340 & 360) 100 PSI Min...No more then 40 PSI variation among cylinders