hobhancock

My truck spun a bearing and broke the piston rod. It sat for almost two years now. Just go around to pulling the motor. I found another short block which had a good crank so I thought I would use it. Took it to a machine shop and had it cleaned and bored oversized .020. Put it all together last week and it fired right up. I was pretty excited to say the least, but soon notice all the smoke coming from the exhaust. At first I figured it was just burning off oil in the cylinder. It never stopped. Then I noticed I had oil dripping from the lower portion of the exhaust pipe under the manifold. So, my next step was to try a better head gasket and replace the valve stem seals. Done. Again put it all together and it starts great and idles so well. But again, still smoke coming for the tail pipe. This time I havent seen the oil come from the manifold, but something is coming out. I read somewhere that loss of vacuum pressure will cause oil to go into both the intake and exhaust manifolds(True?) I havent checked any vacuum to this point. New pistons and rings. When I removed the head this past weekend, obviously, there was coolant in the cylinder, but only a small amount of oil floating on the coolant. I am just not sure that the rings could be the problem. I hope to not have to remove the complete engine again. Have I missed something here? Before it spun the bearing and threw a rod, no smoking issues at all. I used the same head since it had a better surface than the one form the used engine I got. Thought maybe valve stem seals were old enough and could be the issue. The truck is a 1995 S10 Pickup 2wd 2.2l. I currently has 226k on the clock. The motor had been rebuilt back in 2008. The head is a remanufactured one I put on a few years before the actual first rebuild.

SBchevyfan

When you had the block bored, did they also boil it out to clean all the internal passages? Was the valve stem to head clearance checked? Is your PCV valve clogged?

hobhancock

Yes the block was boiled and cleaned. Before my previous engine went south, my oil pressure was low and at idle would sometimes not register. My oil pressure gauge now shows almost all the way to the top. The valve stem to head was not check. I only checked to see if the valves were tight. I have checked the PCV valve. When I pull the line that comes from the valve to the plenum, the idle revs. I had another valve so I put it in and did the same thing. By the looks of that line going into the plenum, there was very little oil. So since I am grasping for straws, I tried a few other things. First I pulled the plug wires and pulled out each spark plug. Cleaned them and put them back and cranked the motor for maybe 30 seconds at a time to see if oil became present. I did not see any more oil on the plugs as long as the engine was not running. I checked compression and get 105 each cylinder. Then I wondered if I was getting oil from a certain cylinder. So I took the exhaust manifold off so I could see each port. Once the engine started and ran for maybe 30 seconds, I could see the oil start to pool at the end of the port. So as I mentioned in my earlier post when I said I hoped to not have to remove the head again. well I did, twice actually. I first wondered if my new head gasket was crap so I took the head off and put another gasket on and replaced the valve stem seals at the same time. Still burning oil and smoking. So I removed the head again (getting pretty good at at this point) and noticed the cracks in the valve seats. So the head that came with the block I had bored, looking it over, was in so much better condition than the first. No cracks or anything noticeable, so I decided to put that one on in hopes it would fix it. Still blowing smoke. I am looking for a miracle here. Can seem to figure out how the oil gets in there other than bad valve seals. The oil is pumped up from the lifters through the push rods and then it just settles back down through the galley on the side. Could it be possible there are cracks around the valve stems that open up just after a few minutes of running that allows the oil in?

hobhancock

Ok, update tonight. Took the head off again this afternoon and have come to the conclusion the new rings are not good. As I crank the engine by hand, I can see an oil line up and down with movement of the piston. Other pistons show signs of oil when the piston reaches the top of the stroke and goes down leaving oil residue on top. I wonder if I just got some crappy rings or if I messed them up somehow. Now I will pull the motor and get new rings.

SBchevyfan

Rings would have been my next guess. Hope you have a warm garage to work in. Just a suggestion, don't just buy new rings and install them. As long as you have to tear it down, I would re-hone the cylinders to remove any little scratches the old rings may have left behind and don't forget to check your ring gap. Good luck!

hobhancock

I think the rings are fine. I think I made a rookie mistake, big time. I did not hone the cylinders after having it bored. From my reading, that will also cause oil to leak past the rings since they are not seating correctly. I do have a good propane heater I use, and yes I will need it tonight. The temps this morning in Utah were 6 degrees warming up to a high in the low 30's

hobhancock

Ok, maybe the rings are not fine. I honed the cylinders now for 60-70 times up and down with my three prong tool. The walls looked really good. Put it all back together and ran it today with again the same result. Still dumping oil out the exhaust. Could running for the 20 miles it has gone since the new rings were installed, have already ruined them? Or I guess the possibility the rings were crap in the first place. I noticed that when I reinstalled the pistons this last time, didnt seem like a whole lot of resistance as I pushed the piston down onto the crank shaft. I see changing the rings for different ones, being my last option here. Anyone have any more ideas I can go with?

Rednucleus

Bored 0.20 over, does that mean you need bigger pistons or different rings?

kevinkpk

That's .020

Rednucleus

Sorry, scotch impaired fingers!