I have one cylinder with ) compression on a dry test and it will come up to 12 lbs with a wet test what would you say it is bad rings or could it still be valves or headgasket ....

No smoking at all on this engine runs great for one dead cylinder in fact. No coolant leak that I have actually noticed I did add coolant once all summer but not enough to realy say it was loosing coolant....

No oil in coolant and no water in oil ...had a bad shudder that I had asked transmission shop about and they said it was the miss ...lol had the transmission serviced Torque converter drained nee filter and fluid and no more shudder at all...

I have not done a complete test of all cylinders yet,but I bought new plugs today and will be checking each cylinder as I do replace plugs tomorrow to rule out low compression on other cylinders while I have the compression guage to use.

 

I would bring the bad cylinder up to the top ready to fire, and then put shop air on a sparkplug adapter and see where the air is coming out.

 

a good idea and actualy was in the plan need to get the adapter to do this still ....just out of curiosity how much would the diffrence in a dry and wet compression test usually be ?

I am guessing at what the difference would be on a cylinder that was still holding enough compression to fire and contribute some still.

 

Ok may not have been done quite right but I think it was good enough...took the valve out of the compression tester line and hooked it to 60 psi on air compressor.Leaked straght out exhaust pipe so it just about has to be a burnt valve ...this cylinder had 0 compression when dry tested , so even without locking the engine down I dont think it could have turned the moter enough to open the valves from tdc.

 

your compression problem could be a bent push rod my 4.9 straight six bent a push rod on #3 was holding the vavle open you might want to pull the valve cover take a look at push rods and rockers to make sure there not holding your valve open

 

HMMM well I did take the cover off ..or rather had some one take the cover off and look for valve problems a while back ...but I also took the truck to a tranny shop that told me the transmission was fine too...it was jumping bad I drained torque converter changed flud and filter ....no more buck and jump.same for taking it to a garage here ...wrong garage evidently on someone elses recomendation...they could not even find the cylinder that was missing, replaced everything I had just put on new the day before,punched holes in plug wire boots to test them..and left the wires off the tranny when reassembled...I was pissy that day with a shop owner.

I can do this its well worth my time, thanks .I will take a look to verify push trods before going into a head repair...I will be having the heads done anyways but if its a mior thing at least she will drive good while we wait on the good garage to have a slot...I will be taking her to the mechanic my dad took her to for 15 years instead of one someone says is good.