Compression Check diy request

[93F22A6]

I just wan't to know the correct way and some guidence on this before I tryed it. Basically what all do I have to do. Thanks in advance.

[EXR-ALB]

Step 1) Remove all spark plugs. (Cranks over easyer if there all out).

Step 2) Remove ignition and fuel pump fuses. (You don't want spark or fuel for this test).

Step 3) Screw in compression tester. (I start with cyl. #1 to avoid confusion)

Step 4) Crank over engine 4-5 revolutions.

Step 6) Take your reading. (140-170 psi is a good range, as long as all four cylinders are even.)

I usually take two readings, one with engine cold and another with engine hot.

If by chance you have a reading of say 70 psi on one cylinder but 140 psi on all others, put a squirt of oil into the low cylinder and re-test.

If compression doesn't rise to match other cylinders you may have a blown headgasket or burned or bent valve.

Sorry if you wanted pics I just stumbled across this and did a quick write up.

I can do a photo DIY tomorrow if you'd like. Just leme know.

[93F22A6]

Thanks, I don't need the photos. I just wanted to know how to do it the correct way.

[tear2wo]

any way to do this with the engine out of the car?

[Shag Wagon]

I either have extremely low compression or either Im not doing it right. Ok the last time I tested my wagon it read 135. I went down the street and tested a D-series that ran GREAT and it only read 80. My wagon pulls REALLY strong with the F22a1 and I cant understand it. I also tested a wonderful running 93 EX and it only had 120 psi and once again that thing was STRONG! Im starting to really think im screwing something up but I have always followed the instructions on the second post.

[WilliamW]

Did you put a small amount of oil into the cylinder and retest it?

What this does (just explaining for those who don't know) is create a better seal around the piston rings. You can have enough wear on the rings where compression will leak by (also known as "Blow by") but any fluid can not easily be forced through and thus creates a seal to get an accurate reading for compression.

If your valves are just a hair out of timing or your head gasket is blown, adding oil will not change the read out. If and only if you have bad piston rings will the compression be bumped up.

[immeraufdemhund]

that or you don't have the compression tester skrewed in all the way. Is the rubber gasket still intact and in good shape around the base of your tester? it sounds to me like your not getting it skrewed in enough.