350 smoking VALVES or RINGS No.2 Cyl only

[TopDogg]

have an 89 4x4 with a 350. Motor was running strong. 1 week ago motor didnt smoke AT ALL. I had the intake off due to leakage and I noticed oil inside the intake runner on the head and a little inside the intake itself. Only on NO.2 cylinder. The motor just started smoking the other day out of nowhere.. The exhaust manifold also has a small crack in it right by the spark plug. If I take the coil wire off and crank the motor oil will actually come out of crack in the exhaust manifold.

The motor was ran for awhile out of time by previous owner.
Motor still runs strong.
I took out all the plugs from that side and inspected before I knew which cylinder it was. No.2 plug seemed to be getting a little hotter than the others but it wasnt caked with oil.

Whats the best way to tell how oil is getting into cylinder?

[bduff509]

The first & easiest thing to do is a compression test. Check each cylinder dry & record the results then check each cylinder after squirting about a tablespoon of oil into the plug hole. If you see a big difference in one or more cyl.'s you're going to want to pull that head to find out why. If all cyl.'s are close & you get better with the oil but still close, you're just worn out & probably need a rebuild. Worn or cracked rings could cause enough blow-by to fill your intake with oil through your pcv valve. My son just had his#4 wrist pin shift on him that gouged cyl. wall beyond repair. The rebuild only had about 2k miles on it. He's pretty pissed at the guy that installed them for him. Now it's either resleeve it or throw it out. The oil only being in the #2 port seems a little odd but could just be a bad valve stem seal. This only a theory but bear with me. As the piston nears the bottom of the stroke it slows down. The air is still moving fast & when the valve closes it dead-heads against the valve, builds pressure, & then reverses direction, possibly taking some oil off of the valve stem with it. That may sound like a stretch but it would be easy enough to check out. After 15 yrs. you're probably due for seals anyway. Again theory but you're #2 seeming a little hotter may be due to the crack in the manifold causing reduced back-pressure. Good luck. Let us know how you make out.

[TopDogg]

I am 3rd owner of truck. Second owner told me before he got it about a year or so ago that the bottom half was rebuilt about 50k ago give or take.

I was thinking the exhaust leak might have caused the heat which can cause damage as anyone would know. Not to mention he was running it way of timing which could also raise the temp.
I was having sudden temp rises before I got timing right.

One might say that smoking on acceleration is rings and smoking while deacceleration is valve seals. It smokes at idle. I noticed it first while I was going from 0 to 60. Sitting at stop signs it gets heavy.

[bduff509]

You can suck a lot of oil up into your heads through your rings under deceleration too. I used to have a '63 Impala- 283 & a 'glide. I used to pull it into low to get down a steep, mile long hill going into Bethlehem, Pa. When I'd pull out of the light at the bottom of the hill you couldn't see anything behind me. That was about 30 years ago. You'd never get away with that around here now.
Watch out for the "just rebuilt" thing. I know several people that got stuck by that one. One guy replace the rear main seal & called it rebuilt. Unfortunately it's hard to tell you got screwed until it's too late. Unless it's your daily driver buying a bad but rebuildable engine isn't a catastrophe. If you have the means to do it, rebuilding an engine is easy enough & Northern Automotive Warehouse has a complete 350 rebuild kit for $150. You can make a deal to swap out the stock cam ( it's only worth about $25 though). The rings don't last so you'd have to get a decent set of moly top rings ( not expensive) & cylinder boring around here ranges from $12- $ 20 / cyl. . For less than $500 you can have a near new motor, head work included. I raced a motor that I built from that kit for 3 years until the oil pan got ripped off driving over my front bumper.

[amac209]

just go ahead and change the valve seals. this can be done in an afternoon. i had to change mine because of blue smoke. a lot of the time if you rebuild the top end on an old motor it will suck oil past the rings the opposite is also common which seems to be your problem.