'01 Jeep Cherokee Sport, inline 6, ~75,000 miles.
I replaced the spark plugs in my Jeep about 3 months ago. After I picked them up at the parts store, I failed to check them all to make sure they were all the same kind (huge error) and installed them. It turned out that two of the plugs that were given to me were of a different type and heat range than what was called for. The Jeep was started 4 times and run for approx. 1 min. each time with the mismatched plugs. The idle was very weak and rough. Realizing the error, the plugs were pulled and replaced. The engine went back to sounding normal, however, now there's a tapping noise that's been isolated to one of the two cylinders that had housed an incorrect plug. I pulled the valve cover and noticed visible markings on the inside of it over one of the cylinders (second from the back of the engine). Naturally assuming that the rocker arm was knocking against the valve cover and causing the noise, I started the engine with the valve cover off, and the noise persisted. I removed the rocker arm and pulled out the push rods. I rolled them on a pane of glass to see if they were bent, and they were not. My next "guess" is that the lifter may be bent (although I'm totally lost on how this could have happened as a result of mismatched spark plugs). Reading in my Haynes manual, it says that a lifters should NEVER be replaced without replacing the camshaft, and vise versa. I'm curious to know if this is true, and am simply trying to exhaust all of my options before having to take it in somewhere. Also, the process states that in order to remove a lifter, the cylinder head needs to be taken apart, which is not something I'm willing to do at home due to my inexperience. I haven't run the Jeep since the problem has been discovered. I don't know if the mystery tapping noise is something that will cause further damage should I operate it? At the same time as the spark plug replacement, I also changed my oil and put in a new filter. I had been having issues with the oil pressure maxing out from time to time and after changing the oil pressure sending unit, it seems to have taken care of the problem. I don't know if the two problems are realted or not though. I assumed not, but then, I'm not a mechanic. Any information you could give me to push me along in the right direction would be GREATLY appreciated. Thanks for your time!
I replaced the spark plugs in my Jeep about 3 months ago. After I picked them up at the parts store, I failed to check them all to make sure they were all the same kind (huge error) and installed them. It turned out that two of the plugs that were given to me were of a different type and heat range than what was called for. The Jeep was started 4 times and run for approx. 1 min. each time with the mismatched plugs. The idle was very weak and rough. Realizing the error, the plugs were pulled and replaced. The engine went back to sounding normal, however, now there's a tapping noise that's been isolated to one of the two cylinders that had housed an incorrect plug. I pulled the valve cover and noticed visible markings on the inside of it over one of the cylinders (second from the back of the engine). Naturally assuming that the rocker arm was knocking against the valve cover and causing the noise, I started the engine with the valve cover off, and the noise persisted. I removed the rocker arm and pulled out the push rods. I rolled them on a pane of glass to see if they were bent, and they were not. My next "guess" is that the lifter may be bent (although I'm totally lost on how this could have happened as a result of mismatched spark plugs). Reading in my Haynes manual, it says that a lifters should NEVER be replaced without replacing the camshaft, and vise versa. I'm curious to know if this is true, and am simply trying to exhaust all of my options before having to take it in somewhere. Also, the process states that in order to remove a lifter, the cylinder head needs to be taken apart, which is not something I'm willing to do at home due to my inexperience. I haven't run the Jeep since the problem has been discovered. I don't know if the mystery tapping noise is something that will cause further damage should I operate it? At the same time as the spark plug replacement, I also changed my oil and put in a new filter. I had been having issues with the oil pressure maxing out from time to time and after changing the oil pressure sending unit, it seems to have taken care of the problem. I don't know if the two problems are realted or not though. I assumed not, but then, I'm not a mechanic. Any information you could give me to push me along in the right direction would be GREATLY appreciated. Thanks for your time!
Jun 18, 2007 at 12:43 PM