Mitsubishi Repair: my eclipse makes a load noise, mitsubishi eclipse gs, vacuum leaks

Question
QUESTION: I have a 1997 Mitsubishi eclipse gs spider with a 2.4 non turbo engine manual Trans. It was fine it needed a motor mount in the front because it would move like crazy. So I replaced it and did a oil change and tune up new plugs and wires. Now it makes a knocking noise almost like a rod! but sometimes it's not constant and it sounds much loader at the top of the motor then the bottom. I put back the old plugs to see if there is a difference and there was not. I pulled the valve cover off and had my father slowly crank the engine to see if there was something out of whack or broke and everything looked fine. I checked the timing belt and it looked ok and the belt was tight I'm lost on this because i would think it was a rod but it comes and then it will stop for a min or two and then come back and the motor funs beautiful and smooth with the exception of the cranking or knocking noise please help thanks.

ANSWER: Kevin: What weight oil did you put in the car when you did the oil change? 5/30 weight? Some of those new light, light weight oils? Try putting in a bit heavier weight oil like 10/30 weight. Also go to the parts store or Wal-Mart someplace like that and see about a engine conditioner. Something about quieting the valves, engine noise well like that. Had a car like your's with a sometimes noise sometimes not. The engine run fine, with or without the sound. It was a kind of pull your hair out kind of deal. I finely put in a heavier weight oil, that conditioner and told the people to just drive it for a while. I never really found the problem. The heavier oil seemed to help, though. Some engines just need a heavier oil in them. My repair manual has some idea on this, so you could try them if the oil does not help your problem... incorrect grade of fuel, ignition timing incorrect, fuel injection system faulty, inproper or damaged spark plugs or wires, worn or damaged distributor components, EGR valve not functioning and vacuum leaks. Hope this helps and God bless: Linda

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QUESTION: well i have tried putting in thinker oil and still the same. I'm thinking its a rod. I don't know I out thinker oil in and was thinking it would go away but nothing changed at all. It sounds like it is the back of the motor behind the intake. what do you think?

Answer
Kevin: Oh shoot, I was hoping this was an easy fix. I guess you will have to do a rebuild on your engine then. Sometime has let go and will have to be fixed or it will just get worse. And if you let it go, it will take the engine. Sorry wish I would help you more. God bless: Linda