compression changed irregulary - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

xka24detx · 05-18-2006, 01:04 PM

i checked compression today after overheating and seeing alot of smoke come out of cylinder #4 head area the results are way off from when i checked it when i first got the car, i know its boud to change over time, but this change is confusing me... i dont know if something is blown, not sealing right, etc...
i havent tried the putting the oil in the cylinder test in #4 yet to see if it raises, just wanted to get your opinions

before
1=175
2=180
3=175
4=180

Now:
1=190
2=195
3=175
4=165

and to just add as a note #2, 3, 4 plugs looked to be burning good light greyish, but #1 was yellow, literally yellow, and on pdm's site on "how to read plugs" they dont say anything about yellow plugs

mistert · 05-18-2006, 03:21 PM

that is pretty strange, doesnt look to be a big enough change to be a blown head gasket

perhaps the yellow is old burnt up oil in cylinder number 1? I've found small bits of oil on my plugs before (everything is resealed now, doesnt happen anymore) but it wasnt burnt yellow yet

zerogrips13 · 05-19-2006, 06:57 AM

if there is a difference between any cylinder of more than 15 psi there is a problem...

seems like u blew your head gasket or weakend it by overheating

jdm_s14_zenki · 05-19-2006, 12:06 PM

sounds like piston rings to me. #3 and #4 rings are taking a shit. might wanna try doing a leakdown just to make sure ur valve seals are good and valves arent bent.

05-18-2006, 01:04 PM	#1
xka24detx Zilvia Member Join Date: May 2005 Location: Santa Clarita, CA Age: 35 Posts: 222 Trader Rating: (0) Feedback Score: 0 reviews	compression changed irregulary i checked compression today after overheating and seeing alot of smoke come out of cylinder #4 head area the results are way off from when i checked it when i first got the car, i know its boud to change over time, but this change is confusing me... i dont know if something is blown, not sealing right, etc... i havent tried the putting the oil in the cylinder test in #4 yet to see if it raises, just wanted to get your opinions before 1=175 2=180 3=175 4=180 Now: 1=190 2=195 3=175 4=165 and to just add as a note #2, 3, 4 plugs looked to be burning good light greyish, but #1 was yellow, literally yellow, and on pdm's site on "how to read plugs" they dont say anything about yellow plugs

05-18-2006, 03:21 PM	#2
mistert Pearl White Mike Join Date: Oct 2001 Location: memphis TN Posts: 908 Trader Rating: (0) Feedback Score: 0 reviews	that is pretty strange, doesnt look to be a big enough change to be a blown head gasket perhaps the yellow is old burnt up oil in cylinder number 1? I've found small bits of oil on my plugs before (everything is resealed now, doesnt happen anymore) but it wasnt burnt yellow yet __________________ "He who makes a beast of himself gets rid of the pain of being a man" ~ Samuel Johnson

05-19-2006, 06:57 AM	#3
zerogrips13 Leaky Injector Join Date: Apr 2005 Location: cbus , ohio Posts: 135 Trader Rating: (0) Feedback Score: 0 reviews	if there is a difference between any cylinder of more than 15 psi there is a problem... seems like u blew your head gasket or weakend it by overheating

05-19-2006, 12:06 PM	#4
jdm_s14_zenki Zilvia Addict Join Date: Jan 2006 Location: Orange County Posts: 703 Trader Rating: (1) Feedback Score: 1 reviews	sounds like piston rings to me. #3 and #4 rings are taking a shit. might wanna try doing a leakdown just to make sure ur valve seals are good and valves arent bent.