1994 Saturn SL2 Compression Test - Do I need to replace piston rings?

First time doing a compression test. Apologies for noob comments during the video : )

Cylinders 1, 2, and 3: 210 psi right away

Cylinder 4: 170 psi

After adding a capful of oil to each cylinder, they all go up to between 225 and 250, with the 4th cylinder at 235.

The things I'm reading say piston rings are worn. The difference between the first 3 and the 4th is 40 psi. The difference after adding the little bit of oil is +/- 12.5 psi across all 4 (less than 6% variation, or 10% from highest to lowest).

So the question is, is it bad enough to warrant an engine rebuild?

I used to get 36 mpg freeway now I'm getting 30. Some of that could be due to other problems though.

Comment away!

Category:

Autos & Vehicles

Tags:

• compression
• test
• worn
• piston
• rings
• saturn
• sl2
• 1994
• psi

[l3lackout77]

Is 210 on all cylinders GOOD or BAD? I just had a motor shipped to me that is a 3.1L V-6 and the compression test showed 210 on all cylinders...Thanks

[jessebickeldotcom]

@l3lackout77 For this vehicle 180+ is the acceptable range. I never bothered doing anything about it because 170 is good enough.

It depends on your car though. Check the manual (official, Haynes, or whatever else is out there) for specifics. Or visit the forum dedicated to that car or engine and find out.

[ratkocos]

your doing the compression test wrong. First take all the spark plugs out. second the engine needs to only turn over 5 times not 8-10. and also a compression on the engine is still good if its between 100-125 psi

[jessebickeldotcom]

All plugs are out in this video. Every Saturn-specific guide I read said 7-10 times.

I have not done anything about the 170 compression, not worth messing with, I think 180 is "good" range, so I'm ok with 170. That was my original question with the video, so I appreciate your response!

Is there a danger in turning it over too many times?

[td1238]

Book says that service limit is 180. Rings are probably worn or stuck in grooves, or have lost their temper. Saturn rings often lose their temper, which causes excessive oil burning. Likely you can replace the rings without replacing any other parts. Replaced my rings at 219,000 miles.  Crosshatch still present. No cylinder wear. Bearings, valves, and guides all perfect. Replace valve guide seals, though. Good idea.

[mrjost55]

@jessebickeldotcom Possibly just your battery dying. Most guides I've read or watched say to crank 5-6 times with the gas pedal to the floor(so that gas doesn't come out of the injectors). I need to check my service manual for the proper procedure.

[dozedrift]

Do you drive this car daily? Did you do this test on warm engine? it could just be one of the valves not seating properly. If it did come down to worn rings, drive it till she blows. Its a saturn not worth rebuild, just find a new motor if it dies.

[JasonsBack100]

@ratkocos hey i have a 2004 cr 125 2 stroke bike the compression is 120 is that good?thanks

[AndrossUT]

Do an MMO piston soak and test again.

[ratkocos]

every thing is good with the engine. there is no danger of turning the engine over a lot except burning the motor out

[jessebickeldotcom]

Thank you helper.