Compression Test Question

[Lee Ann]

Hi All,

RE: 1997 Saturn SC2, DOHC, 4 cyl. MFI

I am gearing up for my compression test and I have a couple fuel system questions.

Fuel System: I have seen two different ways to disable the fuel system, clear flood mode and pulling the fuel pump relay.
1) Now, my Haynes Manual says that I need the throttle plate open during this test. Does that automatically mean I need to use clear flood mode? Should I also pull the fuel pump relay?
2) And once all the spark plugs are removed and the compression gauge is hooked up, the gas pedal is fully depressed while cranking 5-7 times (I think Eric referred to the sound as a gallop)?

Ignition System: I know that I need to disable the ignition system by pulling the electrical connector under the coil pack/module (DIS design).

Thanks in advance for your reply.

Topic

[college man]

Disable the fuel pump by either pulling the relay or the fuse.
Remove the air intake duct to expose the TB.Foot to the floor
to open the butter fly. Crank the car until the needle stops
going up. record your reading.

[Lee Ann]

Got it.
Thanks.

[Kurt Holloway]

You can also check the rings by squirting a little oil in each cylinder and see if your reading goes up it means that you rings are shot or getting worn. because the oil will seal the piston in the bore.

[Lee Ann]

[quote=”Kurt1997″ post=99237]You can also check the rings by squirting a little oil in each cylinder and see if your reading goes up it means that you rings are shot or getting worn. because the oil will seal the piston in the bore.[/quote]

Thanks for your input.

So if the wet test values increased significantly compared to the dry test values then this would indicate worn rings (or out of round bore), correct?

My original compression tests (dry and wet) which may be recorded in this thread were run using a cheap compression tester. I repeated the dry test on Cyl 1 (which had the lowest original value) using a MAC tester (190 psi). The spec is 190 psi standard and the service limit is 180 psi.

Want to run a leak down test to confirm rings or valve(s)issue…after my finger heals.

[Kurt Holloway]

That is a very good idea and yes if the reading goes up then it indicates bad or worn rings

[Author]

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