#3 cylinder is dead; Why? Read on.

Ok,

I'll start out by saying that I did use the search function, and being new to the world of multi-cylinder engines, I found some good tips and ideas. First, I did eliminate which cylinder is not firing, and it's the third. It doesn't change sound with the wire removed from the plug. I have changed the plug wire, to no avail. Odd thing: it's getting spark. I verified it with an in-line spark tester (one of the few benefits of being a chain saw mechanic); the other three cylinders are firing as well.

I'm going out on a limb on the idea that my timing hasn't changed, and the distributor is tight and working (I'm guessing) like it should, at least for the other three cylinders. Fuel is definately there; I pulled the plug and it was wet, some soot, but not much.

So, to make a long story short (which is good for me), I changed the one plug on cyl#3, fired it up, and it ran... well, like it did before. It was a long story just to tell ya'll "Thanks, ya'll are a great group here, and the tech advice is fantastic."

 

Check the compression on all of the cylinders. The lowest should be at least 80% of the highest. If you are getting spark and fuel it sounds like there is no compression on the dead cylinder.

 

Right on with the compression check. it is possible that a valve is out of adjustment and not closing completely.

 

I'm guessing that you're fiddling with a F-134. I had one in a 64 CJ-6 I used to own and it burnt exhaust valves a couple times. Acted just as you describe. It was eventually replaced by a Chevy 283. Best thing that ever happened to that Jeep and end to all engine problems. Wish I never sold it.

 

as already said,compression check will tell all,and one other possibility is that there was so much gas in that cylinder it fouled the new plug instantly,sometimes when i have a badly fouled cylinder i will pull that plug,and start it up for a few seconds with the plug out to clear the cylinder,or use a propane torch to ignite the fuel in that cylinder,my guess its time for a valve job

 

Compression check didn't reveal anything... Put some MMO in the gas and crankcase, hoping that will help. I have a 4.3L to build and put in with a 465 tranny.... all I need is, money. Thanks for the tips, gang. Ya'll are great.

 

meaning 0 compression on that cylinder ?
or 120lbs compresion ?

 

:iagree: if you got good compression it has to be ignition,anybody else got any input? only other thing i can think of would be a bad cam,and that should have showed up in the compression test,have you done a leak down test?

 

fire is getting to the cylinder, but is the PLUG firing? take that plug out and see if it'll fire. could be bad plug or plug that is leaking to ground. I've played that game a couple of times. fuel + spark + good compression and it has to run.

 

Bad head gasket can let coolant into the cylinder and short the plug, especially after standing overnight, but not show much loss of compression.

I've had that condition more than once.

Pete

 

haven't had a chance to do a leak down yet.

compression was pretty good, the high was 118 and the low was 105 or 106...