#2 misfire

[fergmonster]

ok i just rolled another broken cherokee into the garage, got a good deal on it. Before i do a motor swap i'm going to to some detailed diagnosis. I have checked for spark, its good. i pulled the valve cover, looks as it should. I bought it from a guy who said the spark plug disentigrated in that cylinder.... running lean i'm thinking. So now i can pull the dip stick. and it has blow back coming out of the tube. What do you guys think? hole in piston? we'll find out soon i just wanted to know if this has happened to anybody else on here?

[SteveB05]

Do you get any compression on that cylinder

[rksnc]

You need to do compression test. A cylinder leak down test would even tell you more. If pcv system not working you would feel what you think is blow by.

[fergmonster]

whats the proper method to doing a cylinder leak down?

[unclewbbl]

I have a 85 cherokee 4 banger and the same thing happened I pulled
the #2 and it was broken & bent at the electrode,
I thought great pieces in the cylinder chamber tried fishing out and
nothing came out I even removed the oil pan and checked for metal
still nothing put all back togather w/ new plug and did a compression check on all cylinders and had #1 150p.s.i #2 130 p.s.i #3 150 p.s.i
#4 150 p.s.i then started motor and sounds like I have a sticky lifter
but still runs half way decent.
I dont know what to do next, Thinking about doing engine swap
to a chevy v6 f.i. any help would be great

[rksnc]

you have to have a the tool for leak down test. It uses 2 gauges. You apply 100lbs of pressure into cyl and the 2th gauge shows how much pressure it will hold. 100lbs in 85lbs held is a 15% lost. 10% is fine but 20% starting down hill and any more losty than that would be a problem.

[AlohaBra]

Originally Posted by rksnc

you have to have a the tool for leak down test. It uses 2 gauges. You apply 100lbs of pressure into cyl and the 2th gauge shows how much pressure it will hold. 100lbs in 85lbs held is a 15% lost. 10% is fine but 20% starting down hill and any more losty than that would be a problem.

Another thing that can be done.....You need a air compressor and usuallly I use the hose that is on the compression gage or the old SuN machine.....on each cylinder set it for TDC or top dead center using the distributor rotor position. Pump compressed air into each cylinder one at a time and using a stetescope listen at the crankcase or oil fill cap for crankcase or cylinder ring leakage. Then listen at the intake manifold for intake valve leakage. Take out the oxyen sensor and listen there for exhaust valve leakage. The cylinder piston must be at TDC with both valves closed ( you can take the valve cover off to verify this if you want).