Diesel_In_AK
08-16-2004, 01:45 AM
Greetings to all...
Here is a "troubleshoot challenge to anyone who may have suggestions. The scenario: DAY 1, truck runs great, but a mild "clunk" is heard. DAY 2, each time the truck is running, it makes a nearly deafening rattling/metal-to-metal/scraping sound at idle and during deceleration. When accelerating between 0-55, the engine runs nice as quiet as normal, but reach 55+, or level out at 40-55, or decelerate from any speed and the rattle comes back. The flexplate/ring gear is straight, tight, and all bolts are present. There are no metal shavings in the oil. My next theory is that the "clunk" sound was maybe a link snapping on the timing chain, and the the excess noise is absent when the chain is under tension (acceleration) and returns when not (idle, cruising speed, etc.). Also, the new noise seems to be worsening quickly, and I'm guessing the blown link on the chain is falling apart more with each test start and the chain is dragging on the inside edge of the cover. Drivelines/running gear are all fine. NEW engine installed about 100,000 miles ago; transmission has 283,000 and appears to still be in great shape. I'm ruling out rockers because the noise would have to be more consistent with ALL OF THEM knocking at the same time (and as loud as both valve covers being off at the same time), and I'm guessing the same with lifters and/or rods. Basically, the noise sounds like spinning a bicycle chain to a high speed and then dragging a nail across the top of the links and then amplifying it by about 4000%. Any ideas? Thanks in advance!
Here is a "troubleshoot challenge to anyone who may have suggestions. The scenario: DAY 1, truck runs great, but a mild "clunk" is heard. DAY 2, each time the truck is running, it makes a nearly deafening rattling/metal-to-metal/scraping sound at idle and during deceleration. When accelerating between 0-55, the engine runs nice as quiet as normal, but reach 55+, or level out at 40-55, or decelerate from any speed and the rattle comes back. The flexplate/ring gear is straight, tight, and all bolts are present. There are no metal shavings in the oil. My next theory is that the "clunk" sound was maybe a link snapping on the timing chain, and the the excess noise is absent when the chain is under tension (acceleration) and returns when not (idle, cruising speed, etc.). Also, the new noise seems to be worsening quickly, and I'm guessing the blown link on the chain is falling apart more with each test start and the chain is dragging on the inside edge of the cover. Drivelines/running gear are all fine. NEW engine installed about 100,000 miles ago; transmission has 283,000 and appears to still be in great shape. I'm ruling out rockers because the noise would have to be more consistent with ALL OF THEM knocking at the same time (and as loud as both valve covers being off at the same time), and I'm guessing the same with lifters and/or rods. Basically, the noise sounds like spinning a bicycle chain to a high speed and then dragging a nail across the top of the links and then amplifying it by about 4000%. Any ideas? Thanks in advance!