Okay heres the deal, went out to get some hay, ran truck for about 2hrs, no problems, only square bales in the bed, nothing heavy, got home, let truck cool as usual, cut off, started back 30 min later and there is one heck of a knock, sounds like an exhaust leak, but I search it over twice and found nothing, oil is good, pressure good, runs smooth, but this is a LOUD knocking. Sounds like it is on the lower driver side, accelerate slightly and it speeds up and is louder, any suggestions? Sorry for the long over explanation, but I figured I would put as many details, needed or not. ANYTHING yall, I know with all yall someone can help, Thanks
Josh
P.S. never heard anything like this prior to now

 

Pur, I have had various noises over the past month or so. Mine is not necessarily a knock but a loud tapping noise. Like tapping a fingernail on glass. I have also noticed a rattling noise in the 6 speed. Add to it a severe whistling noise (sounded like a vaccume leak on a gas motor) that went away after about three minutes. From what I can gather, most of these point toward an injector problem. Even an occasional valve knock that has came and went. I have got an appointment tomorrow morning at the ***********!!

 

mine had the valve knock too and found a good dealer who fixed that problem, I would name the dealership if allowed, but unsure(admin??) they were highly recommended and turned my truck out in 2days, they also noticed the CP3 had a small leak and replaced it no questions asked, I would assume that the injectors would fall under the engine warrany?? since I have no tuners/chips, I will schedule one for tomorrow
thanks for the response

 

Got mine back from the dealer. They couldnt find any injector issue's but did run some updates based on some TSB's that were out there. The smoking, rattling and ticking seem to be doing better. I havent had a starting problem since I have had it back but before it didnt do it all the time. Still got some rattle in my 6sp but I will just have to monitor that and see where it goes.

 

Mine is going in tomorrow with a knock while going down the road . It started about a month ago and would go away and then come back . I have been under the truck at least 20 times trying to figure it out but can't put my finger on it . I took the service manager for a ride yesterday , he was on lone from their Chevy dealer and he said it sounds like a loose flywheel , maybe a loose torque converter since it is a auto but I don't think so . I dropped the little cover plate when I got home and from what I could see everything looked ok in thier . I ' am just glad he is not the one working on my truck , the diesel mechanic out in the shop seems ok . He told me they have sensors they can put under the truck and listen to were the noise is coming from by shutting them off one at a time until they locate it . I tried to get a friend of mine to lay on a creeper while I was going down the road but he chickened out on me so I guess I ' am stuck with the dealer , it is still under warranty so it is their problem anyway . The noise is the same with transmission in neutral rolling down the road or in gear and seems to disappear at highway speeds . It doesn't matter if under load or not the knock is the same and it sounds to me like it is in transfer case to me but I will let them see if they can find it tomorrow . I will let you know what they find Fri. I hope .

 

Does it sound like a sledge hammer hitting the side of the block?

 

It is not that loud ,sounds about twice as bad as a bolt in a tire . I don't think it is engine related but not sure . I was thinking about going down a small hill and shutting engine off and see if it goes away . The noise does not speed up with RPM of the engine , the thing is driving me nuts finding it , hope dealer is better than me .

 

My noise turned out to be both front axle outer u-joints were bad . Once they got it up on a hoist it was quite obvious but on the ground they looked fine . The noise sure didn't sound like u-joints but that was it . I guess it would be another argument for a set of lock out hubs , my 91 had 130000 before they needed replaced .

 

My Truck did the same thing last night turned out to be a droped valve seat on # 5 ex valve you can hear it in tail pipe the tapping noise is the piston hitting the valve

 

Update:
Dealer found nothing, said he really could not hear it over the exhaust!?
Seafoam and M/M oil, full tank, 450miles of HARD driving, sound is GONE, assume it was build up on an injector. Truck runs smoother than it has in a while, thanks for yalls replies on the matter.

 

Don'tcha luv it!!!! Forget the dealer and drive the snot out of it. The Cummins will heal itself!!!

 

Lightman just a little too much heat there eh?? Under fueled at high rpm or over fueled at low? Burnt exhaust valve seats will tell the tale.

Rick

 

Underfueling will never cause a Problem since they are underfueled by design.