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low compression in three cylinders

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Old May 6, 2012, 07:26 AM
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low compression in three cylinders

I did a compression test and found 125psi, 145psi, 135psi, 165psi

im thinking its my valves or valve guides are worn, what do you guys think it could be ?
Old May 6, 2012, 09:04 AM
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Go to a shop and have them do a leakdown test. That will give you a better idea whats up.
Old May 6, 2012, 09:07 AM
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Stock block? How many miles?
Old May 6, 2012, 09:52 AM
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You have a stock cams?
Old May 6, 2012, 10:54 AM
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Sounds like your testing method is off
Old May 7, 2012, 11:03 AM
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stock block with stock internals no cams my cars at the shop thats where we found low compression
Old May 7, 2012, 11:09 AM
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Did they do a leakdown?
Old May 7, 2012, 11:24 AM
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+ 1 leakdown
Old May 7, 2012, 11:27 AM
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id say that still pretty good compression. Probably just some dirty valves.
Old May 7, 2012, 03:44 PM
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Originally Posted by escodotcarter
id say that still pretty good compression. Probably just some dirty valves.
125 and 135 are below 10% and need to be addressed.
Old May 7, 2012, 03:53 PM
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If the car is running well, let it be---thinking you are trying to fix a problem that doesnt exist...so you are high on one cylinder--doesnt mean you are low on 3. if the numbers were 110 or less then maybe...but really? Look at the one that was 165 one more time and see if you get a different reading. The 3rd cylinder is the one to watch that tends to go before the others.
Old May 7, 2012, 04:47 PM
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im waiting to hear the results from the leak down i asked to have it done on thursday im still waiting and i did the compression check 3 times cylinder 1 2 3 are low 4 is at 165 spec is 175
Old May 7, 2012, 04:49 PM
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Originally Posted by Redline-Z
125 and 135 are below 10% and need to be addressed.
true but personally I wouldn't go and tear apart the motor for that.
Old May 7, 2012, 04:51 PM
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i dont run at 90% thats how problems occur if there is an issue you fix it its called preventative maintenance
Old May 7, 2012, 05:10 PM
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i found this in the service manual

"Standard value (at engine speed of 250 r/min): 1,000 kPa (145 psi)
Minimum limit (at engine speed of 250 r/min): 637 kPa (92 psi)"

with that spec is my motor fine and has high compression in cylinder 4? now im confused!


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