Compression Test Results??...Good or Bad??

ok so i recently blew my stocker in my 97 and bought another 4.0 out of a 94 for 175 bucks to replace it with. it had been sitting for 2 yrs on a pallet in a garage so it was a mystery buy but i took the chance. i pulled the valve cover and oil pan and its got some nasty sludge build up. i then decided to compression test it to see how the rings are. i spun the motor over with a ratchet and socket 5 to 6 times each cylinder with the tester in each hole.
the oil pan was still off and it sounds like air is leaking bad around the pistons and seaping into the crank case.
here are my results..
1-45psi
2-60psi
3-40psi
4-10psi
5-40psi
6-40psi
these seem extremely low but im curious if they are just low because i had to turn the motor over by hand.
let me know what u think and if my rings are garbage or this seems ok
thanks :cheers:

It is normal to hear air leaking past the rings into the oil pan during the compression stroke. However, it is not possible to take a compression reading using just a ratchet and socket on the front of the engine. You need to use the starting motor and a good battery. This is how I usually do it:

1) Remove all the spark plugs, (that will allow the engine to turn over easier)
2) Open the trottle to its maximum and block it open,
3) Insert the compressionn tester into the cylinder being tested,
4) Using the starter, turn the engine over for a few seconds and read the compression when it is at the maximim.

The reading you got indicates that all cylinders are bad,...very bad,.... which is unlikely. I think it is because the engine is not turning over fast enough.

Now you have the oil pan etc; off will be a good time to replace all those pesky oil seals.

Good luck.

ok. well is there a way to spin it over fast enough without having to fully install it in the xj and use the starter? because i have the option of getting my money back on this motor if it is in bad bad shape. thats why im trying to decide if its worth it or not before i throw time and money into it and putting it in my jeep

Bolt a trans to it, or at least a bellhousing. Add starter, power, ground, voila.

thanks. ill try that method. since im putting a 94 and in my 97 should i swap over the 97 intake or anything else to the new motor?

The problem w/ a motor that has been sitting for a couple of years, the cylinder walls are dry. Need to put a cap full of oil in the cylinder.

you can do a leakdown test with the motor out, but you need an air compressor and a testing tool

lilredxj99 said:

The problem w/ a motor that has been sitting for a couple of years, the cylinder walls are dry. Need to put a cap full of oil in the cylinder.

Click to expand...

Good point. I forgot that.