MolaKule
Staff member
Had you used HPL Engine Cleaner or Rislone Engine Treatment you may have had the same or better experience.I bought a new 92’ GMC with the 4.3L V-6 that had a serious knock when starting that would immediately go away. Wouldn’t do it every time. I talked to a GM mechanic and he told me when that engine is cut off that it stops in 1 of 3 positions and to mark the crankshaft pulley and see if it did it only in one position. I did and it did. He said it was a lifter bleeding down and to try the MMO. It completely cured the problem and was still running great at 150K miles when I traded it.
Cured the knock.