Question about compression numbers - what to do next.
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Honda-Tech Member
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Question about compression numbers - what to do next.
Picked up a 2000 Honda Accord with 129,000 miles. Has a misfire cylinder #1. Compression test showed the following:
cylinder 1 - 50
cylinder 2 - 150
cylinder 3 - 170
cylinder 4 - 170
after adding some SAE 30 oil to cylinder #1 compression is now 120. What does this mean? What’s the diagnosis? Bad rings or bad valves?
cylinder 1 - 50
cylinder 2 - 150
cylinder 3 - 170
cylinder 4 - 170
after adding some SAE 30 oil to cylinder #1 compression is now 120. What does this mean? What’s the diagnosis? Bad rings or bad valves?
MM Gruppe B
Joined: Feb 2009
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From: 94577/Gaillimh
Re: Question about compression numbers - what to do next.
Usually when adding oil to the chamber if the PSI increases it's usually the rings/cylinder is no longer sealing.
If the valves are not properly seating/sealing they can also contribute to a lower than expected/desired compression. Might want to verify they are properly adjusted and retesting before punting for a new/low mileage engine.
Lower compression on #2 may be indicative of a head gasket issue as well. If the oil gets pushed into the leak that would allow build up of pressure for the test.
If the valves are not properly seating/sealing they can also contribute to a lower than expected/desired compression. Might want to verify they are properly adjusted and retesting before punting for a new/low mileage engine.
Lower compression on #2 may be indicative of a head gasket issue as well. If the oil gets pushed into the leak that would allow build up of pressure for the test.
MM Gruppe B
Joined: Feb 2009
Posts: 7,016
Likes: 108
From: 94577/Gaillimh
Re: Question about compression numbers - what to do next.
If you can beg/borrow/steal a borescope to observe if the cylinder walls are scored that would save you time from tearing down the engine.
Did the coolant or oil have any discoloration or seem contaminated?(blown head gasket)
Did the coolant or oil have any discoloration or seem contaminated?(blown head gasket)
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