WHY IS THERE OIL ON TWO OF MY SPARK PLUGS HAS ...

1999 Mercury Cougar

Tiny

kennethmorrow

October, 24, 2012 AT 1:27 AM

Why is there oil on two of my spark plugs has really bad compression and is making a hissing sound

5 Answers

Tiny

mhpautos

October, 24, 2012 AT 10:19 AM

Oil on the plugs and low comps usually mean broken rings or a hole in the piston, get a leak down test done this will help pin point the problem.

Tiny

kennethmorrow

October, 24, 2012 AT 12:45 PM

What is a leak down test

Tiny

mhpautos

October, 24, 2012 AT 7:44 PM

This is when you apply a low pressure compressed air into the cylinder at TDC with both valves closed, there is a special tool that screws into the spark plug hole, with the low pressure applied you can determine where the leaks are, such as valves, rings etc.

Tiny

kennethmorrow

October, 24, 2012 AT 8:03 PM

Can I do the leak down test myself or do I hav to take it to a shop

Tiny

mhpautos

October, 24, 2012 AT 8:06 PM

You need the adaptor a compressor and a regulator to drop the air pressure down, to high a pressure will force the piston down and open a valve this will give you a false reading, if a manual transmission you can put it in gear and pull the hand brake on to help hold the engine at TDC.

Please login or register to post a reply.

Spark Plug Replacement Ford Explorer 4.6L V8
Spark Plug Replacement Mercedes Benz C230
Spark Plug Replacement Honda Element
Spark Plug and Wire Replacement Ford Mustang
Spark Plug Replacement Toyota Tacoma
Spark Plug Replacement Mercedes Benz ML500