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Bent push rod and oil on the plug?

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65springtime:
I put new plugs in the Mustang and drove a few miles and noticed a little knock so I pulled the valve covers and found one of the rocker arms was not on the push rod so I also pulled the intake manifold (was going to pull it anyway) and sure enought the push rod was bent. I pulled all the plugs out and the plug on number 3 pistion had oil on it and that is where the bent push rod was. What would have caused oil to be on the number three plug? Thanks

jethat:
A damaged piston ring or a damage piston.. if you have another push rod you could put it in and do a compression test but most likely you got some piston damage and it will bend the pushrod again.. might be time for a overhaul or get another engine..

65springtime:
This is the OE 289 engine that came on the car and will not be getting another engine. If it is the piston then an overhaul is in order. I have a new set of push rods.

Jeff73Mach1:
Pushrods get bent from overrevving, improper adjustment, detonation, backfire and other things as well.

I wouldn't take a bent pushrod to mean much on its own.  Oil on the plug is usually from blow by and/or bad valve stem seals, but an inoperative PCV system can lead to plug fouling as well.  While it may be true that a broken ring or damaged piston is possible, I wouldn't jump to that conclusion.

BTW not many people realize how often spark plugs are bad.  Dropping a plug can cause it to not function properly without any visible damage to the exterior of the plug.
Just because you didn't drop it doesn't mean it wasn't dropped.

How far did you drive and how much oil was on the plug?  What color was it?  Was it an intake or exhaust that had the bent pushrod?

A compression test will tell part of the story.  A mechanic's scope can look through the spark plug port and see some types of damage.

65springtime:
I am no mechanic but I would say intake because it is not over the exhaust port. After putting in the new plugs drove it about 20 miles and the car just was not running right still. Had the carb rebuilt and a lot of other things but the knock got to me and I was going to paint the engine and pull the intake anyway and that is when I found the bent rod. We did not drop any plugs. There was not a lot of oil just enought to get it wet. The color looked norman. You can push the valve down easy. Just could not understand the oil on the plug. The guy I bought the car from was only about 19 so yes he could have over reved it because he sold the car because he was scared of the manual shifting. He dould not handel it. So he could have. He did not have the car very long. Also when you let out on the clutch from a stop, you would have to play with the clutch to keep the car from jumping a little just when starting from a stop. Could that be the clutch itself? I really appreciate the help.


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