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Discussion Starter #1
iv just done a compression test on my mk4 gsi turbo the results are

cylinder 1= 176 psi
cylinder 2=168 psi
cylinder 3= 90 psi
cylinder 4= 170 psi

soooo, whats up with my engine :beer:
 

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head gasket, ring problem, cracked block etc. try and get a leak down test done,
 

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cylinder 3 looks like the bad egg
 

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Discussion Starter #5
so if it was a stuck/bent valve or head gasket id see this by taking the head of, but if it is the rings i take it ill will need the pistons out, another thing iv noticed is the turbo water pipe bubble,fizz alot when hot and im getting loads of pressure in the header tank
 

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sounds like head gasket or cracked blocked then!
 

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so if it was a stuck/bent valve or head gasket id see this by taking the head of, but if it is the rings i take it ill will need the pistons out, another thing iv noticed is the turbo water pipe bubble,fizz alot when hot and im getting loads of pressure in the header tank
You could take the head off to see if its valves or head gasket, pressure test it ect but If you empty your oil out and put all pistons half way down the bore and put diesel in each one, If cylinder 3 which looks the suspected one drains the diesel first then you know its piston rings.

From what you've said though it sounds like headgasket as the water system is getting pressurised.
 
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Discussion Starter #9
iv had 2 mechanics have a look and both said its either rings or a melted piston, is there any way of telling if its a cracked block ?
 

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yes, block oout and have it pressure tested and or X-rayed!
 

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Discussion Starter #11
ill get it tested when i get it out and all stripped down, it was rebuilt by vauxhall 8k ago, its still under waranty but im not wanting it rebuilt with standard parts
 

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i'd get it done under warrenty, then afterwards pull apart and fit uprated parts, at least you will know that if the block is fuked they will have to replace it.
 

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Hey guys, going to check compression on a gsiT id fancy buying next week. What is the correct compression reading , if there is any, or should i just look for consistancy?
 

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Consistency is key, but anything over 165 PSI isn't too bad for a z20let. As long as you get less than 10 PSI variance across all 4, it shouldn't be far off.
 
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