Low compression in all cylinders

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Originally Posted by Blknight.aus

no pics required.

get an old spark plug, gut it and weld a air line fitting to it.

remove all your spark plugs and wind that one into the pot you want to test.

turn the engine over by hand (use a ratchet on the nut on the alternator pully) untill the engine is a TDC compression stroke on the cylinder you want to test

apply compressed air to the spark plug/airline adapter

listen for air leaks at the exhaust pipe, air inlet, oil filler and other plug holes.

if you get "some" leakage out the oil filler, put 15-20ml of thin engine oill down the cylinder wind the engine slowly for 4 full turns of the crank then repeat the test at TDC compression. if the leak is stopped then its not likely to be your rings

Allow the engine to slowly turn over to test the integrity of the ring seal at various positions of the stroke.

done.

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Sounds like a plan. A few things i'll need to sort first though;

- How can I see TDC - looking through the empty spark plug hole?
- What if i'm getting leakage from the exhaust - is it rings?
- Should I just find someone professional to run these test for me (Graeme Cooper advised after the compression test that there were no more tests they could do!?)

She's definitely using oil but no leaks, so i'm guessing rings. It's running ok, maybe a slight miss but can't see an issue continuing as is aside from the oil consumption. So, I should really sort this out one way or another.

Dave

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Originally Posted by LavisLane

Sounds like a plan. A few things i'll need to sort first though;

- How can I see TDC - looking through the empty spark plug hole?
- What if i'm getting leakage from the exhaust - is it rings?
- Should I just find someone professional to run these test for me (Graeme Cooper advised after the compression test that there were no more tests they could do!?)

She's definitely using oil but no leaks, so i'm guessing rings. It's running ok, maybe a slight miss but can't see an issue continuing as is aside from the oil consumption. So, I should really sort this out one way or another.

Dave

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G`day Dave ,

it`s disapointing to read a story like yours , i don`t mean how your car is behaving but what you`ve been told .

A basic compression test that doesn`t follow all the rules will only be any good to find a major fault in a cylinder or cylinders and only 1 set of figures suggests this .

The fact you`ve been told there are no more tests , for mine in this instance would indicate i found another business to spend my money at and the reputation i`ve read of for Coopers would be of no influence after what you`ve been told , they may have had an off day but it`s your money .

I`d suggest you Google " compression test " , " leak down test " , " vacuum test " and how they are used , the procedures that need to be followed and their relation to diagnosis of an engine .

Peter .

no more tests......?

how long a list of diagnostics tests would you like and would you like that list limited to my field type tests or the ones where I go and get all scientificy and bring out/borrow some serious techology?

theres a few ways of assessing TDC...

the easiest is with a long shank screwdriver that fits in the spark plug hole, wind the engine over a bit and poke the screwdriver in slowly turn the engine over and it will rise, once its stopped rising bingo TDC.

wind in the spark plug with the air fitting (do it right and you can get a piece of fencing wire down through that so you dont have to take it out every time to check TDC.

put the air on if you get a massive loss of air you're out 180 on the cam and the valves are open (your transitioning from exhaust stroke to inlet) spin the crank one full turn and your on compression.

in a perfect world there should be no leakage out the inlet manifold
none out the exhaust either
and a small percentage down past the rings (they dont seal perfectly while static)

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Originally Posted by Blknight.aus

no more tests......?

how long a list of diagnostics tests would you like and would you like that list limited to my field type tests or the ones where I go and get all scientificy and bring out/borrow some serious techology?

theres a few ways of assessing TDC...

)

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If your directing this my way .

What is the problem ?

Do you have something to do with Coopers or are you the one that told him there is only 1 test and it`s been done ?

I`d like to see a long and detailed list of diagnostic tests of any kind from anywhere , thanks .

if this is the car i just spoke to Peter Davis about, i think the guys that did the original testing should double check their equipment and their ideas.

Thanks to all for your input. Rupert, correct. Thanks for taking a look at this one.

Turns out that the only low compression is in cylinder 2 at around 105. All other cylinders relatively normal.