Hello all. First post here. I searched and searched and couldn't find info regarding my problem. I have a 1998 K2500 w/7.4L 454 with 125,000 miles. All was well until I had to pull out onto a busy highway. I had to give it some good gas to get up to traffic speed. At higher rpm it started to loose power, run rough and started to hear a loud "ticking/knocking" noise. After 3 or 4 miles it started to quiet down and all power returned. After some more driving, 20-30 miles, and some oil additive, the ticking left completely. Now today, I got stuck behind grandma driving 45 in a 60 so I decided to pass her. I kicked it down and almost instantly the "ticking" or "knock" returned along with the stumbling and loss of power. Again it eventually quieted down to a ticking that could just barely be heard at highway speed. I put some additive in the crank case after the first experience and thought that had addressed whatever was going on, but after today, I now see that the additive (Justice Brothers red can) had no effect. Is there anyone that can walk me through the process of diagnosing the problem? I already shorted out each cylinder individually and noise continued. Any guidance would be greatly appreciated!!!!

 

Nobody here understand this 1998 454???????????

 

Sounds like a bearing or a lifter is going out to me. Those additives only hide the problem for a short time. Could pull the valve covers and see if any rockers are loose. its a good start, and you don't tear into the engine at all.

 

Can a bad bearing cause loss of power and stumbling?