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Compression?

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What kind of numbers should I be seeing out of the Legacy? I got 120psi on all 4; cold and dry. I thought I had seen 170-180 in a thread a browsed awhile back, but I can't find it and am not sure if that was warmed up, wet tested or what. Any help would be super.

Compression is checked warm, throttle wide open. Compression will vary depending on outside air temp and density, but 180-190 psi is about normal. IIRC all 4 cylinders should be within 10 - 15 psi.

Cold numbers are only useful to see if you have compression at all.

 

156- 185, are those your compression readings? Squirt some oil in the one that's low and see if it comes up closer to the others.

What kind of numbers should I be seeing out of the Legacy? I got 120psi on all 4; cold and dry. I thought I had seen 170-180 in a thread a browsed awhile back, but I can't find it and am not sure if that was warmed up, wet tested or what. Any help would be super.

 

That's around the same as I got cold and dry on my 96 2.2. They actually ranged from 115-135 with around 275,000 miles on it. I traded it in at 318k and it was still running strong

  • Author
Compression is checked warm, throttle wide open. Compression will vary depending on outside air temp and density, but 180-190 psi is about normal. IIRC all 4 cylinders should be within 10 - 15 psi.

Cold numbers are only useful to see if you have compression at all.

 

WOT? To what RPM range? Or just put it to the floor and let off a couple of times?

 

156- 185, are those your compression readings? Squirt some oil in the one that's low and see if it comes up closer to the others.

 

Mine are all at 120 cold. Going to test them warm once I find out exactly how to read it.

WOT? To what RPM range? Or just put it to the floor and let off a couple of times?

 

 

No, no. :-p The engine isn't running, and shouldn't be allowed to even start when checking compression.

Warm up the engine to normal operating temp, driving or idling doesn't matter. Shut it off and remove ALL spark plugs.

Unplug either the cam and crank sensors (both of them) or the fuel injectors and Ignitor module or coil pack to prevent spark and fuel when cranking.

Attach compression gauge, then hold the throttle pedal on the floor while cranking the engine. Crank it until the needle on the gauge doesn't go any higher. Should only take 3 or 4 seconds.

  • Author
No, no. :-p The engine isn't running, and shouldn't be allowed to even start when checking compression.

Warm up the engine to normal operating temp, driving or idling doesn't matter. Shut it off and remove ALL spark plugs.

Unplug either the cam and crank sensors (both of them) or the fuel injectors and Ignitor module or coil pack to prevent spark and fuel when cranking.

Attach compression gauge, then hold the throttle pedal on the floor while cranking the engine. Crank it until the needle on the gauge doesn't go any higher. Should only take 3 or 4 seconds.

 

FML... My auto shop teacher will be getting an irate call about this.

175 .

 

your gauge has taken a death turn?

 

 

do you have a Snap-On or MAC guage, not asking if you have anything else, anything else is junk throw it away and get what i say for good result.

  • Author
175 .

 

your gauge has taken a death turn?

 

 

do you have a Snap-On or MAC guage, not asking if you have anything else, anything else is junk throw it away and get what i say for good result.

 

Really? Crap, I guess the $200 Snap On tester I calibrated mine to was crap too...:rolleyes:

  • Author
when i got my legacy with 97k on it it had 180 across the board warm of course...

 

Nobody likes a showoff...

 

I'm going to test it tomorrow. I had to get new plugs and wires. Kind of hard to warm up when it only wants to run on 2 cuz you ham fisted the wires and left the clips on the plugs...:popcorn:

  • Author
No, no. :-p The engine isn't running, and shouldn't be allowed to even start when checking compression.

Warm up the engine to normal operating temp, driving or idling doesn't matter. Shut it off and remove ALL spark plugs.

Unplug either the cam and crank sensors (both of them) or the fuel injectors and Ignitor module or coil pack to prevent spark and fuel when cranking.

Attach compression gauge, then hold the throttle pedal on the floor while cranking the engine. Crank it until the needle on the gauge doesn't go any higher. Should only take 3 or 4 seconds.

 

Thanks again for this.

 

Lowest cylinder was 182, highest was 187.

Perfect range! Now...

What is the reason you felt the need to do a compression test? Some issue with the engine, or just curiosity?

  • Author
Perfect range! Now...

What is the reason you felt the need to do a compression test? Some issue with the engine, or just curiosity?

 

Just acquired the car. Getting the punch list ironed out. One less thing to worry about.

I have a customer with over 270k - uses Mobile-1 at 5k intervals since he bought it new in '90. First production year - slam dunk for reliability. Superb engine design and implementation. With the proper maintenance they can easily go half a million.

 

You could use one of his valve covers as a dinner platter.... or meatloaf tray :-p.

 

GD

You could use one of his valve covers as a dinner platter.... or meatloaf tray :-p.

 

GD

 

note to self... never eat meatloaf at GD's house! :drunk:

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