I just found this forum,and hopefully someone can help. I have a 2001 4x4 with a 5.9. just got it a couple weeks ago. before i bought it it had set in a barn for about 1 &1/2 yrs. now the problem. it has a really bad miss, after scanning it showed mis-fire on 5&6. changed the plugs around,wires around,injectors around and the miss stayed with the same cylinders. ran a compression check and found 5 30lbs low. 6 was down a little but not much. pulled the valve cover and was shocked at how dirty the engine was. watched the valves work trying to see if there was something obvious. exhaust valve on #5 was not completely closing after the oil pressure came up. I am now working under the assumption that there is dirt in the lifter,not allowing it to bleed back off pressure enough to allow the valve to completely close. heated up the engine and dropped the oil and filter,went with 5/30 and a quart or marvel mystery oil to try and clean things up. some improvement but happy yet.
are there any other "tricks" i could try? i really don't want to tear this engine down, but that exhaust valve aint gonna last long not closing. Any help would be GREATLY appreciated!

 

Would someone use eng flush on a motor like this?

 

If you havent I would run some seafoam through it, it will clean out alot of the carbon buildup

 

well, lets see. lifters pump up with oil pressure and should not bleed down. the cam moves the pumped up lifter which moves the push rod which moves the rocker which overcomes the valve spring and opens the valve. if anything in that chain fails - the result is an improperly OPENed valve. when the cam rotates out of the way, the valve spring should push everything CLOSEd.

so the only reason that a valve would not close, would be if the lifter was sticking and not dropping back down, or the rocker was sticking, or the valve spring was weak, or the valve was bent, or the seat was misformed or obstructed.

also, if the valve was not closing, the compression would be zero, rather than just a little low....

i'm going to question/challenge that the valve is not closing. are you sure ?

also check the dist cap and rotor. unlike the plugs, wires, injectors that you moved, those would stay the same. also check injector wiring or that the injector is actually firing to make sure a rat didn't eat that wire. check plug wire too for spark.


edit - ^ in a case like this, seafoam's not a bad idea.

 

**** missed that he didnt say anything about cap and rotor, take a look at them if its been sitting they might have rust or corrosion, if they show any signs replace them

 

The valve is not closing due to all the carbon build up on it from the blown plenum gasket.

 

cfi - could you have your open/closed backwards. that maybe the valve is not depressing (opening) all the way. that could be a bad lifter or pushrod.

how much have you driven it yet? just driving it some with fresh oil, fresh gas, a bottle of chevron fuel injection cleaner and it might fix itself.

 

Seafoaming the intake might help too.

 

thanks for all the replys. interesting ideas indeed. i have seafoamed 2 tanks of gas. the more i drive it the better it seems to be getting. i think i'll do another compression test,and see what happens. also going to do cap,rotor,wires and plugs. certainly can't hurt at this point. thanks again for all the advise. i'll keep you posted as to how it comes out.

 

Running full synthetic oil will clean the engine quite well after a couple of changes. Also, use a Motorcraft FL-1A filter to catch all the dirt and sludge that will come out of it. Keep an eye on the color and clarity of the oil on the dipstick, you may have to change it soon after the first or second oil change.Welcome to the forum, and good luck with your Ram.