1.5 compression readings?

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1.5 compression readings?

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1.5 compression readings? - 2/19/2008 5:56:12 PM

90excelGS

Posts: 11
Joined: 2/10/2008
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Hi, what are the compression #'s i should expect from a healthy engine. I'm familiar with the procedure. Thank You...

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RE: 1.5 compression readings? - 2/19/2008 6:06:34 PM

Derrel H Green

Posts: 21
Joined: 11/21/2007
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Not as important as to what the exact numbers should be,
but the differences in those readings between cylinders.

As I recall, the numbers should not be more than 10 pounds apart.

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(in reply to 90excelGS)

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RE: 1.5 compression readings? - 2/19/2008 9:23:29 PM

90excelGS

Posts: 11
Joined: 2/10/2008
Status: offline

Thanks Derrel, So a 10# + variance could be considered as troublesome rather than a precentage of a whole value. I can agree with that.. But I'm still curious of what stock compression should be.

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RE: 1.5 compression readings? - 2/19/2008 10:33:43 PM

ken99

Posts: 399
Status: offline

The Hyundai service site I mentioned in the other thread has a whole section in the General Engine pdf that discusses compression testing. Straight forward procedure as you would guess. Standard pressure is 192 psi with a minimum limit of 171 psi. Differential between cylinders shouldn't exceed 14 psi. Recommends a second "wet" test for any low cylinders, again a pretty standard procedure. It doesn't suggest a "leak down" test, but that would be smart to check valve and/or piston ring integrity on any engine you were preparing to spend money on.

Also, this engine has a rubber timing belt. I couldn't confirm that it is a true interference engine, but being derived from a Mitsubishi design, I would bet it is. You have implied previous service is suspect. I'd check the condition of the timing belt and perhaps change it now if the compression tests indicate an otherwise sound engine. It would be a shame to invest money in the car only to have the engine tank from a broken timing belt.

(in reply to 90excelGS)

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