Correct compression

[jade]

Hi can anyone please tell me what the compression should be on a rs2

Cheers jade

[Audi Parts Guru]

9.3 to 1

[Mark Halligan]

Are you asking for the compression ratio or the compression readings you should see in each cylinder when checking the enigine using a compression tester?

[jade]

Are you asking for the compression ratio or the compression readings you should see in each cylinder when checking the enigine using a compression tester?

Yes thats right Mark just did a compression check this morning & wanted to check what they should be

Cheers Jade

[Mark Halligan]

Ok

figures I have are:

carry out test with engine warm approx 80 C, and throttle open.

• specified values 9.0 to 13.0 bar
  
• lowest servicable pressure 7 bar
  
• max difference between individual cylinders 3 bar

HTH

[jade]

Ok

figures I have are:

carry out test with engine warm approx 80 C, and throttle open.

• specified values 9.0 to 13.0 bar
  
• lowest servicable pressure 7 bar
  
• max difference between individual cylinders 3 bar

HTH

cold engine Just ticked over for a moment
Open throttle
8.5 bar all the same
Hows that sound
Cheers Jade

[Mark Halligan]

Well they are all the same, which is good.
I'd try it again though, with the engine (and coolant) warmed up to operating temp for a closer idea of whats happening when the motor is running.

[s2dude]

cold engine Just ticked over for a moment
Open throttle
8.5 bar all the same
Hows that sound
Cheers Jade

Yeah. Agree with Mark. When the engine is up to full operating temp....and throttle is wide open during compression test.
I'm sure the numbers will raise by maybe a bar each cylinder.

For the conditions you did it under though 8.5 bar all cylinders seems A1

[Jamo]

This has saved me putting up a post, cheers Mark H

Can i suggest this is moved to the BTDT section as it's quite helpful

[SteveH]

Make sure the throttle is open, you'll get much lower readings if the engine isn't able to breathe. I thought there was a minimum temp for the test of 50 degrees C, could be wrong though. I managed 12 Bar on my motor after a rebuild, but I doubt it's that good now. The important factor is that they are all pretty much the same. If you have a wide deviation between cylinders, there's something up.

[Jamo]

Found this in another thread:

How To Do The Compression Test,

Run the engine until it reaches normal operating temperature. Tests done on a cold engine usually show lower readings. Remove the HT leads and take out all the spark plugs. The ignition system MUST then be disabled. If this isn't done it will continue to generate high tension voltages into the HT leads which will have nowhere to go with the plugs out. These high voltages will find another route to earth and can damage the ignition system or even the car's ECU. Unplug the low tension connections to the coil or to the distributor. If you aren't sure how to disable the ignition system on your own car then check with a dealer before you start. It is also good practise to unplug the fuel injectors or disable the fuel pump, especially on cars fitted with a catalytic convertor. This prevents unburned fuel getting into the exhaust system during the test.
Screw the gauge into cylinder 1 and rest it somewhere you can see the dial while you crank the engine. Open the throttle fully either by pressing the accelerator or wedging the linkage open under the bonnet. If the throttle isn't open then air can't get into the cylinder and the readings will be far too low. Crank the engine until the gauge stops rising and count the revolutions while you do so. It should normally take no more than 10 engine revolutions (5 compression cycles) to get a full reading. You can count the cycles by watching the gauge too - each jump of the needle is one compression stroke. Write down the final reading and also make a mental note of how quickly the gauge rose on the first few cycles. Then just repeat for the other cylinders. Make sure that each cylinder reaches its highest reading after the same number of engine revolutions. If all readings are good then the test can end there. If any cylinders are low then a "wet" test can be done. This involves squirting a few ccs of oil into the cylinder and repeating the test. The oil will help seal bad rings and increase the reading but won't affect it if the problem lies in the valves or head gasket

[Billman]

...disable the ignition system on your own car...disable the fuel pump...

How can these be done in our cars??
Are there any fuses witch we could disconnect'?

[A80Avant]

actually i didnt really understand how it is done,and what this compression tester is used,but i would like to have mine measured sometime...

[s2dude]

actually i didnt really understand how it is done,and what this compression tester is used,but i would like to have mine measured sometime...

ok. Its easy.
Buy one of these

http://cgi.ebay.co.uk/Sykes-Petrol-E...ayphotohosting


then warm teh car engine up.
Then remove a spark plug from each cylinder in turn and crank the engine over for the number of times it says on the tool you bought.
the gauge will give you a reading......take one from each 5 cylinders and make sure they are all within the manufacturers tolerances....
if they are all very similiar thats good though

[Jamo]

How can these be done in our cars??
Are there any fuses witch we could disconnect'?

I've got an ABY dont have to worry about the ignition, removing the coil packs should be sufficient i would imagine.

I intend too remove the fuel pump relay to stop it activating.