Showing blue smoke under acceleration?

JCW49

MEMBER
1997 HONDA CIVIC
4 CYL
FWD
MANUAL
145,000 MILES

Son drove car with low oil level. Now using 1 qt oil for every 400-500 miles and showing blue smoke under acceleration. Tried "oil restore" additive but only provided moderate reduction in showing blue smoke. I am a weekend mechanic and not sure how to determine if the problem might be valves or piston rings so wondering if replacing piston rings would be a worthwhile first step to repair this problem? Or with a high mileage engine such as this should we just consider a re-built or used engine replacement instead?

1 Reply

SQM

MECHANIC
6,383 POSTS

Hello,

As you know the blue smoke is due the engine burning oil.
Now you could have piston rings leaking and allowing oil to enter the combustion chamber.
First you need to do a compression test for all the cylinders.
You can get a compression tester from you local auto parts store, they will usually rent those.
You should have minimum of 135 PSI of compression and the maximum variance between the highest to lowest cylinder cannot be over 28 PSI
Here is a helpful guide of compression test:

https://www.2carpros.com/articles/how-to-test-engine-compression

If the compression is low on one or multiple cylinder you can test to see if it is low due to piston ring, by pouring a table spoon worth of oil thru the spark plug hole, then testing the compression again. If the compression rises then you have a leaky piston ring.

I have attached diagrams for your reference.

Please let me know of any questions.
Thank you.

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