I have a 2002 4.7 jeep runs rough n stals out on
idle bring it to bout 1000 rpms n it smooths out but
let off the gas n idles rough n dies just replaced the
water pump n did a compresion test n have one
cylinder that isnt geting any compresion the front
cylinder on the passenger side front dont now
wether its the head gasket stuck valve or bad
You have a bad valve by the sounds of it with 0 compression. Squirt some oil into the cylinder and do another compression test. If the compression raises at all then it is the piston rings. If it stays the same then there is a bad valve.
Do i need to take the head completly off if its a bad valve ? N how much work is detailed in puting new rings in
Yes the head would have to come off. But depending on how many miles are on the engine determines what kind of work is worth doing it to. You want to squirt the oil in the cylinder and recheck the compression so you know what is going on.
I have 160,000 miles on the engine but the car is in great shape no rust on the body and absolutly no rust on the framen i only paid 200 for the jeep n have 276 in it after replacing the water pump ill have to squirt the oil down in the morning im done for the day
160,000 I'd say your in a boat and need to decide on a used engine, or a new engine. A remanufactured engine is about $3100. It would not be worth fixing this engine unless you are capable of rebuilding it.
I didnt think 160,000 was o to bad i have another jeep with almost 200,000 n still running im a mechanic n have almost all the tools to do almost any kindd of work gunna take the head off n inspect the valves n change the head gasket n see were we go from there thanks for your help
Then you would just be replacing the 1 valve that is bad. That would be fine. You should know if you did a total head job that you would probably make it into an oil burner. That was my underlying thought.
I have been there before; it is most likely that one of the rocker arms has flown off, which is common with Jeeps. If you don't want more trouble, change all hydraulic lifters. Be careful because inner bolts on the cylinder covers on both banks are not easily accessible. This picture shows when one of my rocker arms had flown off.
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