Guys why are my plugs wet with oil ??

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This topic contains 11 replies, has 4 voices, and was last updated by  Wayne & Judy Miller 4 years, 10 months ago.

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    I have fresh 390 with 120lbs compression on 8 cylinders. And I’m trying to figure out why I’m burning oil ? Any suggestions ?


    What process did you use to “seat” the rings? Also, are all the spark plugs wet with oil or just one or two? How much oil are you “burning”?



    I followed the instructions that I got from the guy who did the motor.  I ran it at different intervals at different rpms for about 30 or 45 min or so. Then I just kinda went easy for a little while. I only had headers on it so i didnt drive it much. But i had a rocker arm back off and it broke my push rod and lifter. I fixed that then immediately put some pipes on it and started driving it. Thats when I started noticing the smoke and it has progressively gotten worse. I’m burning like 1.5 quarts every 100 miles or so. With fwall 8 plugs wet.  Its horrible. And driving me crazy :/ !  But it runs great thats what’s weird.



    Will a leak down test tell me anything ?


    A leak down test will tell you if you are losing compression through the valve train or past the compression rings. You have plenty of compression but it won’t hurt anything to do a leak down. Using 1.5 quarts of oil per 100 miles is extrememly excessive even for an engine with, oh say, 200,000 miles on it. The oil is getting past the oil rings somehow. It could be from internal engine pressure caused by no venting of the crank case (a plugged PCV valve if so equipped) or a restriction to atmosphere in the down draft tube. The other thing that could be causing this much oil use is improper oil rings or improperly installed oil rings. I think it is time to have a discussion with the “guy who did your motor.” One other thing that could cause oil in the cylinders at this rate is a bad fuel pump if you have a dual action fuel pump. If the vacuum side of the pump is bad it will suck oil out of the crankcase at a prodigous pace.



    I just replaced the fuel pump to check that out. I have a new pcv valve in it that connects to the back of my new holley. I’m trying to excercise every option possible before tearing it back out I just put it in. My uncle gave me the block he bought it from his “mechanic” who “rebuilt” it 5yrs ago. Come to find out he didn’t but his friend did. Really unsure of what all is done to it. But the guy is telling me that i must have washed the rings out. I’m really upset with this hole situation as I have got tons of money and and even more time in it. I did everything by myself so tearing it out again would be a big dissapointment. Could it be possible that I have a intake leak ? Could that do it ? And I’m also running stock heads.



    And what is the down draft tube ?


    The down draft tube vented the crankcase to atmosphere before closed crankcase venilation systems (PCV) were required. I don’t remember what year closed systems became required but I think it was in the early 60s. The downdraft tube came off the intake manifold and went down to exhaust the gasses under the car.

    Don’t think an intake leak is going to cause the kind of problem you have. It may be time to yank it back out and look at the internals.



    If I’m not in q position to pull the motor right now how much damage am I going to do if I keep driving it. Other then replacing plugs and wasting oil ?


    Probably none as long as your wallet can afford the oil and plugs.



    plug your pcv valve an try that, My Merc used 1 1/2 quarts in less than 300 miles. it was sucking oil right out the engine, all that oil and no smoke from the trail pipes. The tail pipes were always wet.


    Wayne & Judy Miller

    Had similar problem with burning oil and oil being blown out onto the engine . It turned out to be a defective oil breather cap . Hope this helps .

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