#3 cylinder is fowling plug with oil
07-26-2017, 06:09 PM
#1
Thread Starter
Join Date: Jul 2017
Location: MA
Posts: 24
#3 cylinder is fowling plug with oil
1996 mustang gt 4.6 fowles plug as soon as i start it.and if i drive it its smoking terrible what could this be.all other cylinders are great.valve seal? i just bought the car 1 1/2 months ago
07-26-2017, 10:56 PM
#2
4th Gear Member
Join Date: Nov 2009
Location: SoCal
Posts: 1,826
Maybe there's a 3rd way that just escapes me, but I can only think of two ways really that this is happening.
Bad valvestem seal or worn piston rings. I'd run a compression test before anything else.
Something else you can check just for shiz and giggles is crankcase pressure. Engine idling, remove the oil fill cap and observe whether there is vacuum or positive pressure. More commonly known as the "dollar bill test"; place a bill of your favorite denomination over the fill opening and if it blows away then that is (not always, but often) indicative of combustion chamber pressure leaking into the crankcase. There should be a slight amount of vacuum at idle. Either way I still recommend a compression test at this point in time, just thought I'd give you an idea for something fun to do. If compression test turns up negative results (the good kind of negative), then move on to suspecting valvestem seal.
Bad valvestem seal or worn piston rings. I'd run a compression test before anything else.
Something else you can check just for shiz and giggles is crankcase pressure. Engine idling, remove the oil fill cap and observe whether there is vacuum or positive pressure. More commonly known as the "dollar bill test"; place a bill of your favorite denomination over the fill opening and if it blows away then that is (not always, but often) indicative of combustion chamber pressure leaking into the crankcase. There should be a slight amount of vacuum at idle. Either way I still recommend a compression test at this point in time, just thought I'd give you an idea for something fun to do. If compression test turns up negative results (the good kind of negative), then move on to suspecting valvestem seal.
Last edited by Z28KLR; 07-26-2017 at 11:05 PM.
07-28-2017, 01:08 PM
#3
Thread Starter
Join Date: Jul 2017
Location: MA
Posts: 24
how hard is it to change valve seals just on those 2 valves?do you have to take the cam out that side?i can put a new plug in that hole and start it and it fowles plug right away.its like there is oil leaking down the stem as soon as its started.....all other plugs are burning perfect.i just bought the car about 2 months ago and only put 400 miles or less on it.when u 1st start it the smoke isnt bad but when it warms up gets worse and worse.2 quarts in a 100 miles bad.its like its just pouring down that valve.any help would be great thank you so much Jeff
07-28-2017, 01:29 PM
#4
Thread Starter
Join Date: Jul 2017
Location: MA
Posts: 24
#3 hole fowles as soon as u start
it will use 2 qts of oil in 100 miles.its like there is no valve seal there at all.all other plugs burning perfect.could a seal let that much oil though it>any help would be great thanks Jeff newbie here.....