Hi all, most of my forum comments are typically regarding TJ's as it is my jeep that I take wheeling. TOday's post is regarding my DD. My DD is an 01 WJ, 4.7, and 95k on the clock. I need your help.
Today drove an hour away from my home to deliver a snowmobile I just sold. Ran great. Stopped at a gas station on my way home to pick up a soft drink, and seemed to be running fine when I shut it off to run inside.
I came back outside just a few minutes later, jumped in, turned the key to start it and it came to life with a horrible knock, like a LOUD rod knock, not like a metallic pinging. I immediately killed it and looked under the Jeep to see the only liquid dripping on the ground was condensation from the A/C. (I thought that it may have thrown a rod) Coolant level checked out, engine oil in the "Safe" zone, I did not see anything abnormal on the dipstick.
Went back start it again, knocking was still there, but much more subdued than it was just a few minutes before. Oil pressure gauge was reading normal, engine temperature was right at 210, or slightly below it. After just a very short time, the knocking completely left, it is now non-existant. HOWEVER, it runs extremely rough, I know for sure it isn't firing on all cylinders, likely more than 1 is not firing. The wind was blowing just right so that I could smell the exhaust and could smell unburned fuel.
Thought for some reason that the ECM had a freak out session, disconnected the battery for 15 mins, and reconnected it, nothing changed. I called around, and got it on a trailer, now its back at home.
The starter does not labor heavily when turning the engine over, I can hear the fuel pump prime when the key is turned on, and will even rev when throttle is applied though it still runs rough.
I am clueless as to where to start, is this a common occurrence with the 4.7? Any ideas of what it can be? How can I check it before taking it to a mechanic?
After reviewing the situation multiple times in my head, the only thing that I can think of is that the timing chain skipped a tooth, or broke which allowed the valves to come in contact with the piston(s) and bending. I assume that this could produce a loud knock while they are bending, and after being bent, they won't make much racket. From my research, the 4.7 is an interference motor, is this correct?
At any rate THANK YOU so much for the time you have taken to read this, and if you have any suggestions of what could be going on, I would appreciate your assistance.
Today drove an hour away from my home to deliver a snowmobile I just sold. Ran great. Stopped at a gas station on my way home to pick up a soft drink, and seemed to be running fine when I shut it off to run inside.
I came back outside just a few minutes later, jumped in, turned the key to start it and it came to life with a horrible knock, like a LOUD rod knock, not like a metallic pinging. I immediately killed it and looked under the Jeep to see the only liquid dripping on the ground was condensation from the A/C. (I thought that it may have thrown a rod) Coolant level checked out, engine oil in the "Safe" zone, I did not see anything abnormal on the dipstick.
Went back start it again, knocking was still there, but much more subdued than it was just a few minutes before. Oil pressure gauge was reading normal, engine temperature was right at 210, or slightly below it. After just a very short time, the knocking completely left, it is now non-existant. HOWEVER, it runs extremely rough, I know for sure it isn't firing on all cylinders, likely more than 1 is not firing. The wind was blowing just right so that I could smell the exhaust and could smell unburned fuel.
Thought for some reason that the ECM had a freak out session, disconnected the battery for 15 mins, and reconnected it, nothing changed. I called around, and got it on a trailer, now its back at home.
The starter does not labor heavily when turning the engine over, I can hear the fuel pump prime when the key is turned on, and will even rev when throttle is applied though it still runs rough.
I am clueless as to where to start, is this a common occurrence with the 4.7? Any ideas of what it can be? How can I check it before taking it to a mechanic?
After reviewing the situation multiple times in my head, the only thing that I can think of is that the timing chain skipped a tooth, or broke which allowed the valves to come in contact with the piston(s) and bending. I assume that this could produce a loud knock while they are bending, and after being bent, they won't make much racket. From my research, the 4.7 is an interference motor, is this correct?
At any rate THANK YOU so much for the time you have taken to read this, and if you have any suggestions of what could be going on, I would appreciate your assistance.