i just did a compression test on my motor(gsr block/b16 head) before i installed a turbo and here is how cylinder reads (#1 225) (#2 220) (#3 185) (#4 220). I know there is a huge difference on the #3 cylinder which would explain why when i took the plugs out all of them where fine except for #3 which looked alot darker than the others, almost fouled out. What would cause the plug to do that along with what would cause cylinder pressure drop?? any ideas????

 

i know someones gotta have some kind of idea about this!!

 

Do a leak down test as well. This will tell you better if its your rings or valve seats.

 

you say the plug looks fouled? oil fouled?
its prolly the rings


Modified by mmuller at 1:48 AM 10/19/2006

 

yeah...its got a funky idle to it too!

 

Bent or improperly adjusted valves can cause low compression. Did you add oil to the cylinders and redo the compression check? Thus will test the rings for leaks.

 

had the same problem, do a leakdown test. turned out to be a bent valve.

 

put a table spoon of oil into cylinder #3 through the spark plug hole, then do a compression test again on cylinder #3 if compression goes up to normal it is piston rings, if compression still stays low, it is somthing with the valvetrain/head.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by teler86 &raquo;</TD></TR><TR><TD CLASS="quote">put a table spoon of oil into cylinder #3 through the spark plug hole, then do a compression test again on cylinder #3 if compression goes up to normal it is piston rings, if compression still stays low, it is somthing with the valvetrain/head.</TD></TR></TABLE>

Good ole wet compression test. Works everytime. Helped me narrows things down to piston rings on my old motor.