Tuesday, October 25, 2011

My brother changed the spark plug and the old one has oil on the thread, is their a problem in the engine?

He think some thing crack or broke in the engine.
My brother changed the spark plug and the old one has oil on the thread, is their a problem in the engine?
Depends where the oil came from. If it is not using oil, the chances are it came from the top of the engine, perhaps at a top up or oil change - a little could have been spilled. It could perhaps be leaking from a gasket on the top end, which is usually easy and cheap to fix. Worst case is that it is coming from the engine bores, which could be anything from engine wear to a pressure relief valve blocked.

I would check for any obvious signs of oil on the top end that should not be there and also monitor the oil consumption - it should use less than a pint every 1,000 miles. Most modern engines use virtually none.
My brother changed the spark plug and the old one has oil on the thread, is their a problem in the engine?
It's probably just seepage at the valve cover gasket.
No, if it's just on the threads, it means the valve cover gasket is leaking a little and so oil collects in the plug area. However if the firing tip of the plug is fouled with oil that means something else.
Hard to tell for sure without seeing it, but most likely is that the valve cover gasket is leaking a bit and oil simply accumulated in there and covered the threads when the spark plug was removed. Way to tell... remove the spark plug, and put your finger into the cylinder. Oil in there? Does the car run poorly? If there is a bunch of oil in there, either you have a broken or worn cylinder ring, or even more likely worn valve guides. A compression test will reveal the problem.
I'd say look for a leaking valve cover gasket that would run oil down around the spark plug base.
Probably valve cover leaks or you miss the fill hole and oil runs down the block on to the spark plug. If the valve or rings were bad the plug would be fouled out and you would have a miss or low pressure on that cylinder As you didn't say the plug was fouled out or lose of power check the valve cover for leaks.
Since you did not bother to list the vehicle that you are working on I am going to take a guess and say that you have a car that has spark plugs that go down through the valve cover and have a long spark plug boot to reach the plug. This type motor has spark plug tube seals that go bad and let oil get down to the plugs and the oil slowly works its way down the plug toward the cylinders. This is not too bad to change and can normally be purchased from a parts store for around $20.00 to $30.00 and is called a complete valve cover gasket set. Change that and you should be fine. Hope I have been helpful.
the only thing wrong there is that you need new valve pan gaskets. as long as the oil is,nt on the firing tips on the plugs then there no internal damage.