I have a 2004 Mitsubishi Lancer with 270k+ miles. It has so much wrong with it, that I can't tell new symptoms from worsening old symptoms.

BUT! I noticed that the metal bar that holds my plastic oil cap on was missing. I took the valve cover off and found the bar wedged in, away from the lifters.

I didn't think of the nut until I bought a new cap and saw one on the new cap. There's a real good chance that the nut is somewhere in the engine, oil line, oil pan or oil filter. I have no idea what the flow is from there, or if a nut could pass through any of this.

What should I do next, beside shopping for a car?

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  • I realize I actually asked 2 questions, 1. what will happen? and 2. what should I do? The more important is probably #2.
    – TecBrat
    Feb 9, 2017 at 2:25
  • 1
    Can you take a picture of this metal bar and stud that you're talking about? It's kind of hard to visualize. The nut must still be in the upper part of the cylinder head assuming it's in there. There's not really any other place it could go.
    – Ben
    Feb 9, 2017 at 2:26
  • @Ben Image added. The old one, with the damaged bar on left and a new on on the right.
    – TecBrat
    Feb 9, 2017 at 2:42

2 Answers 2


Sooner or later it will give you headaches and you will need to "at least" remove the valves cover and/or oil sump. If the engine head has open ports that runs down to the oil sump, it may go over there. If it hasn't these, it is probably that the nut is still in the head. It will be a problem if it somehow gets stuck in a valve spring, or around the camshaft, or any moving parts. I would carefully take the valves cover out (carefully to avoid moving the nut if it happens it is somehow touched by the cover) and do a good visual inspection. I would use a thin and large screwdriver with magnet tip, or one of those flexible magnets, to see if the nut sticks to it.

I don't think the nut is in any of the oil passages, nor the oil filter. Those have very thin diameter, and if a piece like a nut would definitely get its way into it, your engine will automatically suffer of oil pressure problems.

As for the new cap: I would either apply Loctite to the nut, or use a rivet instead of that bolt and nut thing.

  • Is "oil sump" the same as "oil pan"?
    – TecBrat
    Feb 9, 2017 at 3:07
  • I think they are the same (I'm not an English language native)...oil sump...oil pan...that thing under the engine that receives and keeps the oil and has a nut to drain it :) Feb 9, 2017 at 3:09
  • Thank you. I'm sure your English is better than my attempts at any other language. Yes, that thing with the drain plug in it.
    – TecBrat
    Feb 9, 2017 at 3:15

Most likely nothing. It will probably just sit in a low spot in the cylinder head vale train area.

If it manages to get jostled enough to make it to the drain holes and into the pan the oil pump pickup will have a screen that will prevent the nut from being sucked into the oil pump.

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