smokey 280z

[PapaSmurf]

Hey guys, I built this engine last summer but got so fed up with this issue that I tucked it away in the garage until now. The car starts runs drives great - the only issue is the smoke. It's a 78 280z with an f54 out of an 81zx. I ported the head painted the block and went through it real good before putting it in. My fear is the rings are bad. The smoke billows out white/grey clouds depending on how I adjust the carbs I can get the grey to lessen if I lean it out all the way. The plugs are soaked in oil immediately after being cleaned. Compression is good on every cylinder 130 to 145psi on all 6 but there is oil on EVERY plug. Could the head just be warped? It seems like I'm burning more water than oil from the color of the smoke. I just went through the carbs and timing today hoping I could tune the smoke away - no luck. I put in all new stem seals when I put this thing together. My first reflex was that the head gasket I used was faulty and I changed it after a day of troubleshooting - it was burned and oil soaked between the first two cylinders. The new gasket didn't solve the problem it was still smoking. I just don't think a warped head would dump oil into every cylinder and I don't see how compression could be good either. Which leads me to oil control rings - someone please rule them out because I don't want to have to waste another summer on another used engine

[KunoZ]

Sounds like your head is warped. Theres no other place for the coolant to come through other than the cylinder wall or through the head, but as you said the compression is good and runs good too, so that eliminates any hole in a cylinder wall and leaves you with the head. You also mentioned that the smoke is mostly white/grey, the white which is technically steam and or coolant and the grey is oil, both cirulate through the head. Smell your exhaust as well, if the smell is sweet then its def coolant. An engine can still run good if it has a leaking head gasket and from my knowledge even still have good compression. What I would do in your case, is pull the head, have it milled or A.K.A. resurfaced by a machine shop, install a good quality head gasket and go from there. Should def solve your problem. Its hard to tell how the previous owner maintained the engine if it came from the junk yard. Could have overheated it pretty bad and in turn warp your head. Although I've seen these engines run pretty hot and still not warp or blow a head gasket, but nothing is unbreakable though. Hope I helped and if anybody else that has some insight it is appreciated.

[PapaSmurf]

That's what I was thinking/hoping but where is all the oil coming from? It wouldn't be in every cylinder if it was a warped head, it forms so fast on the plugs it's unreal. Oil control rings would explain the oil on the plugs and it would still have good compression as long as the other rings were in good order. all 6 cylinders have oil in the combustion chambers that's a new one on me. I'm going to pull the head and have it checked out. I wonder if this more than one faliure ie bad oil control rings AND warped head. Wouldn't compression be lower if the head was letting oil and water in the cylinders? Theoretically the air would go out the same way as the oil and water comes in. It also only smokes really bad once the engine gets warmed up to operating temperature. I wish I had a color tune so I could completely rule out a/f ratio which could be responsible for a lot of the white and grey smoke - white=lean grey=rich

 

Maybe it's bad mixture a warped head and bad oil rings combined into one big glorious mess of confusion...

 

I guess I'll start tearing the head off it'll be a good excuse to be out in the sun and it'll force me to fit the exhaust properly and replace that cracked water inlet (the stupid aluminum piece where the radiator and thermostat are) I have to pull off the crank pully and put on a single belt one and put a different clutch fan in too. It's enough work to keep me busy all summer - I'd better not end up having bad rings once it's all back together I'd cry.

Children are bad they suck away all of my Z time

Edited April 23, 2011 by PapaSmurf

[PapaSmurf]

There aren't any signs of water in the oil or oil in my water...

Edited April 23, 2011 by PapaSmurf

[KunoZ]

So, we have both determined that it is definitely burning oil, due to the oil on ALL the plugs and the grey/white smoke. The white smoke could be due to a lean mixture since there is no evidence of water in the oil, like you said. Also if the mixture of oil is heavy enough it can burn just white smoke, but like I said it has to be pretty heavy, which in your case it sounds like it. Just in case if you can do a simple check, remove one of the spark plugs (preferably #6 cylinder) and the radiator cap. Turn the engine over slowly by hand with a rachet at the crank pulley and hold your thumb over the spark plug hole until you get pressure out. Connect an air line snuggly to the spark plug hole and see if air bubbles or antifreeze comes out of the radiator fill cap. Simple check if you have an air compressor that is. If no fluid is pushed out or no bubbles we can rule out that it is burning antifreeze. But anyways, how many miles does this engine have if you know? My concern is that maybe the previous owner of the engine may have ran it dry without oil or the engine is just plain worn out. Good day and good luck!

[PapaSmurf]

No air tools, I'm just going to pull the head have it shaved flat I'm sure it's at least a little warped at this point in it's life. I'll see how it looks in there before changing the rings.

[Xnke]

Check out your valve stem seals...they leak oil into the intakes when they get worn, or if they get torn during installation. It's pretty easy to mess up a set of seals when you slide the valves into the guides, and if you didn't replace the valve guides then it's possible that they are worn too.

Edited April 27, 2011 by Xnke

[PapaSmurf]

old thread but I haven't had new information for a while. The valve guides were not replaced the stem seals however were replaced when I put this thing together. The guides probably need to be replaced but not without new valves to go with them. I cleaned the old valves but I'm not happy with them still. I've been taking her out for long HARD drives trying to see if it just needed a good break in. The oil burning has lessened substantially! It's possible the oil control rings were stuck or these rings just needed a good burned oil coating to seal them up better. The engine was pulled in a junkyard 20 years ago and moved to their storage warehouse where it sat waiting for me all that time- storage is not good for rings. The water burning however is getting worse. I pulled the radiator cap while it was running and there was a LOT of pressure in there for whatever reason the overflow plumbing was clogged after letting the thing idle up and get warm large bubbles began to plop up from the depths of the radiator and small chunks of oil when I rev the engine high the water level in the radiator goes down as it idles it raises - I would have thought it would go the other way because the pumps rpms would increase with the engine rpm causing increased pressure but I believe as the engine speed increases it is breathing more water and thus it pulls the radiator level down. The head is warped there is no question but I'm fairly certain that the rings are ok - at least now they are. There is still no sign of water in the oil but the oil pressure is far lower than it should be possibly indicating that it is flowing into the cylinders still at least slightly probably due to the head warpage.

 

I need to tear into this thing but it's hard to pull a head while watching a 2 year old...

Edited July 6, 2011 by PapaSmurf

[PapaSmurf]

I made some people really regret driving a convertible mustang, they were following too closely when I gunned it going up the freeway onramp haha smoked them out good they're probably still coughing.