DATSUN671 Posted January 10, 2013 Report Share Posted January 10, 2013 everytime i take out number 1 spark plug, its always oily so i did a top end rebuild, change all the valve seals,head gasket,etc. when i put everything back it will run fine, then again spark plug number 1 is oily. im thinking its the piston oil rings but when i did a compression test, all cylinders are good. i didnt do a bottom end rebuild thanks for the help B) B) B) Quote Link to comment
Eagle_Adam Posted January 10, 2013 Report Share Posted January 10, 2013 what was the reading on all 4 cylinders? Quote Link to comment
Rays74 Posted January 11, 2013 Report Share Posted January 11, 2013 If your compression between the cylinders is nearly the same and enough not to worry (IMO +140), then most likely yes you have an oil control ring prob in that hole. Do you notice much oil mist in the valve cover breather hose? Feel around the outlet (valve cover) when the engine is idling......should be a slight negative pressure there but as the engines age this turns to a slight (or more!) positive pressure and will likely be the sign your engine has some blow by.....this will oil up your plugs too. Our engines are known to hold decent compression but use oil......something to check. My L18 does this, but on number 4 cyl........compression is 145-155 for all of them so it still runs really well BUT I do have that positive pressure out of the breather so my old lower end is experiencing blow by too. --Ray Quote Link to comment
datzenmike Posted January 11, 2013 Report Share Posted January 11, 2013 Are you running NGK plugs? BP6ES? If not these are the factory recomended ones. If oil fouling continues try switching that one plug to a hotter heat range. Try BP5ES. A hotter plug is much more likely to burn off the oil deposits. Note that this is not a cure for bad rings, but it may help. Quote Link to comment
DATSUN671 Posted January 11, 2013 Author Report Share Posted January 11, 2013 I went through alot of spark plugs and still oily in number 1 im wondering if the compression on the cylinders are good, could the oil rings be the problem? Quote Link to comment
ggzilla Posted January 11, 2013 Report Share Posted January 11, 2013 Have you done a wet compression test? Quote Link to comment
datzenmike Posted January 11, 2013 Report Share Posted January 11, 2013 .... but when i did a compression test, all cylinders are good. im wondering if the compression on the cylinders are good.... You said you did a compression test and it was good. what was the reading on all 4 cylinders? So.... what were the readings you got? Quote Link to comment
DATSUN671 Posted January 11, 2013 Author Report Share Posted January 11, 2013 My compression reading on all 4 cylinders were 160psi Quote Link to comment
datzenmike Posted January 11, 2013 Report Share Posted January 11, 2013 That's good! Quote Link to comment
ggzilla Posted January 11, 2013 Report Share Posted January 11, 2013 That's good, but if the wet compression check shows 170, it means the rings are worn. Quote Link to comment
DATSUN671 Posted January 11, 2013 Author Report Share Posted January 11, 2013 That's good! That's good! so my piston rings are still good Quote Link to comment
Z-train Posted January 11, 2013 Report Share Posted January 11, 2013 Compression rings could sghow good,but the oil ring is shot or broken. Quote Link to comment
datzenmike Posted January 11, 2013 Report Share Posted January 11, 2013 Try one hotter range plug. Quote Link to comment
ggzilla Posted January 11, 2013 Report Share Posted January 11, 2013 He's not listening to to us. Yes, the compression readings means NOTHING regarding oil usage. Quote Link to comment
Rays74 Posted January 12, 2013 Report Share Posted January 12, 2013 Well, yes and no, Zilla. Compression is dependent on ring seal, and if that seal is becoming an issue and there is blow by, there will be pressure build up in the crankcase that (if it over runs the PCV system) could cause the engine to start using - wasting oil. In this case it may not be, but it does happen. --Ray Quote Link to comment
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.