Recent compression Test Results

[Bigdunc]

Hi guys u done a compression test on my mk2 8v GTi she dont about 134k

compression is the same in all cylinders between 8-9 bar

is this ok or is this alittle low as read someware should be 13-14bar??

also noticed the plugs on cylinder 3 and 4 were abit oily

is this normal? is head ok?

[Ben Lessani]

Sounds low ish, 11-14 is normal for a NA engine.

Why were you testing the compression in the first place?

[danny_p]

8-9 bar is low,   it'll run but it's proably breathing quite heavly out of the block  and really all the goodness has been worn off.

if its not breathing heavly the valves / seats may be worn so you chould fix/help it by removeing the cyl head regrinding the valves but if plugs are looking oily or have heavy fouling it suggests the rings are very much worn out 

[Bigdunc]

tested as been feeling flat recently. and been getting smoke when cold.

I found my haynes manual after posting this thread and it does say 10-13bar.
I was thinking maybe head needed a recon, which i never done befor but was thinking of buying some good tools and having a go myself.

the plugs arnt to bad but did notice oil. my compression tester is quite old was one my dad used on his mk1 when they first come out so might borrow a newis one off friend just to make sure the tester hasnt got any leaks or anythin.

I done compression test by. unplugging the lead from coil pack going to dizzy, then just turning on engine and checking guage is this correct??

[Bigdunc]

just done some reading i think i done the test wrong, i didnt open up the throttle. ill have to do test again with throttle open ill get a friend to help me this time.

[Ben Lessani]

You don't need a friend. Remove fuel pump relay, remove spark plug, screw in tester, crank engine for 5s @ WOT - then go check the gauge.

[Bigdunc]

my guage dosent stay up after it only goes up and down when turning the key so need to somehow turn key and look at guage at same time

[Ben Lessani]

Ah gotcha, that sucks!

[danny_p]

sadly that means your numbers are useless,   the pipe to the gadgue has a volume and so dose the tube in the gaduge itself.    this effectivlt adds volume to the combustion chamber so it will actualy lower the engines effective static compression ratio.   there should be a 1 way valve in the fitting that screws into the pllug hole usally it's a tyer valve.

get a better cr tester and try again but it think you'll find the number will come up right then, it usally takes several turns before the gadgue tops out to give a true reading