Compression

[CHRI1111]

Morning,

Do these compression readings seem OK to you / within tolerance?

I have a rough idle and engine light and didn't know if these were to blame.

I added a teaspoon of oil to each cylinder and repeated the test which improved the readings leading me to suspect the lower readings are due to worn piston rings.

2006 1.6 FSI 150K.

Thanks

[Magnet]

Nothing happening with the links for me Chris.

Please just list the figures. 
Kind regards,

Gareth. 

[CHRI1111]

Hi Gareth

Cylinder 1: 9.5 bar

Cylinder 2: 9 bar

Cylinder 3: 10 bar

Cylinder 4: 9 bar - although it seems take take a couple more cranks to get there.

With oil added:

Cylinder 1: 11.5 bar

Cylinder 2: 10 bar

Cylinder 3: 13 bar

Cylinder 4: 11.5 bar 

Chris

[Magnet]

Thanks Chris,

They do generally seem on the lower side of normal. 
Could you outline your procedure for testing the compression pressures please.

Kind regards,

Gareth.

[CHRI1111]

Yes, I screwed the gauge into the spark plug socket. Took out fuel pump fuse. Cranked over engine with throttle fully pressed for a couple of turns. Took reading. Put a teaspoon of oil in. Repeated test. Took reading.

Is that right?

It is an old engine so expecting piston ring wear but didn't know if the readings would ordinarily lead to engine light and rough idle.

[Mark M.]

Was the engine at normal operating temperature when you did this?

[CHRI1111]

It was yes, I unscrewed the spark plugs and performed the test after it had gotten up to temperature.

[Magnet]

So all spark plugs removed before testing individual cylinders? 

[CHRI1111]

Hi, yes I removed all spark plugs whilst testing each cylinder.

[Magnet]

Judging from the oil pressure issue you list separately, this engine’s condition sounds poorly. 

[Mark M.]

^^^^^ agreed.