cylinder compression

Chiangstar · Post by **Chiangstar** » Wed Nov 10, 2004 3:04 pm

hey all
does anyone know what the normal cylinder compression should be? i did a compression test on the weekend but i dont have a benchmark to compare to...

cheers

simon

salacious · Post by **salacious** » Wed Nov 10, 2004 11:58 pm

The standard value is 1226kPa with the min being 1030kPa. They shouldn't vary by more than 98kPa between all the cylinders

Chiangstar · Post by **Chiangstar** » Thu Nov 11, 2004 12:51 pm

excellent!

wasnt sure if anyone would have that info
thanks salacious

simon

EURO · Post by **EURO** » Fri Feb 04, 2005 4:06 pm

would a lower compression then that, mean the car would be suffering blow by, or major engine wear?

Chiangstar · Post by **Chiangstar** » Fri Feb 04, 2005 5:59 pm

ah... im not sure what blow by is but if you compression is low, then either your head gasket is gone, your valve arent closing properly (ie bent valve or valve seals gone), your spark plugs arent sealing properly, or your piston rings are fried....

simon

EURO · Post by **EURO** » Sat Feb 05, 2005 4:45 pm

blow by is something to do with gases leaking betweenthe piston and cylinder wall. I think it is a sign of major engine wear, and a proper seal not being made between pistons etc....

if head gasket is gone, would your car still start? and if your piston rings etc are fried... wouldnt u find the car lacking a lot of power? surging.. etc?

thanks chiangstar..

Chiangstar · Post by **Chiangstar** » Sun Feb 06, 2005 11:29 am

if theres a small leak in your head gasket, you car will still start.... youll notice things like your coolant disappearing, bubbles in the radiator water, engine temp increasing, murky engine oil.... but yes it will still start....and the worse it gets, the worse itll perform and eventually just cut out....

i was recently told by a mechanic friend that there can be around 10% variance between each cylinders compression... when you start getting closer to 20% you have to start to worry.... and you will notice it too

Simon

G_A_V · Post by **G_A_V** » Sun Feb 06, 2005 12:48 pm

how do you test cilender compression with a mut-II ?

MarkFTO · Post by **MarkFTO** » Sun Feb 06, 2005 8:32 pm

you need to use a compression tester im afraid. Bit of a pain on the V6 engine unfortunately.