knocking

[bear8236]

Driving to work this morning about 15 min into the trip started hearing a knocking. Not a rattle, but almost like a valve sticking or something. Haven't really noticed any poor performance. We did just have a cold front blow through (living in central TX) so it only got down to 40 or so. Knock can be heard under acceleration and at idle. Don't hear it when I let off the throtle and coast, until it drops back down to idle.
little more info. '02, 3/4, 4x4, 6 speed; about 150k, all 8 injectors replaced 2 years ago, flywheel just replaced about 2 months ago, at that time dealer said engine "passed with flying colors"
oil pressure/level looked normal, engine temp was running lower than normal, due to the cool weather.
I've read some of the other post concerning knocking, and saw something about the pilot injectors?
It's been awhile since I've ran any additive in the tank, was going to dump a bottle of Amsoil diesel additive in the tank to see if that helped.
Any advice would be greatly appreciated! Than

[bear8236]

I've been sitting here thinking,(plus had a few cups of coffee) could it possibly be a thermostat problem? not getting up to opperating temp? anyone ever have a similar problem?

[Jim Brzozowski]

I'm about 160 miles S. of Austin,heard similiar type sound as you describe. I've always heard that in the winter when its cold. I think it may have something to do with the very low humidity of the air after the cold front moved through and that affects the burn process after ignition of the fuel. Mine goes away after warm up is complete. I doubt we have any winter blend fuel this far down in Texas this early.
Just wait until it reaches correct operating temp. before you stand on it.

[bear8236]

Even running at temp of around 180 it still does it. Did seem to go away after sitting out all day in the warmer temp then starting it. Let it run for awhile to let it warm up for my ride home, when i came back out it was doin it again. Doesn't shimmy, doesn't shake, no excessive vibration, no power loss maybe i just need to upgrade my stero system to drown it out :cool:

[Inspector]

I had in my 03s engine what I thought was diesel knock. I took it to the dealer and they did a balance check and found that the #6 was out of bal. running at 5.3 compared to the others at around 0 to 1.5. They changed the injector and that seems to have quieted the knock. A dripping injector will also cause what is called :rolleyes: diesel knock. I'm not sure that an out of bal. injector will cause "knock" but maybe it contributed to the symtom. I've been wrong before.
Denny :rolleyes:

[stc]

Have same symptom with my 01 DA. Have 128K miles with no power modules. Have had no injector work done and do not tow with the truck.

After going for a test ride with my dealers service manager he thought knocking sound was that of piston slap. I replied with three things,1- the noise comes and goes. 2- engine burns zero oil between changes. 3- no white or black smoke from tailpipe. Seems to me if a cylinder was scuffed up and or rings worn that one of the above 3 things would be different!

Would love feedback from any members. Thanks

[crafty]

I would get a balance rate check done on the injectors. You most likely have one that is way out compared to the rest. In the spring, mine was knocking pretty loud every time I started up from a stop. The mileage was great, no smoke etc etc. When they checked the balance rate, number 7 was out of range. The problem disappeared after changing that one. :D :D :D

[Kennedy]

...and run a quality additive like FPPF Total Power in all the fuel that you burn!

[CHVYMAN#9]

Have your dealer run a power balance while driving when the noise occurs. They can shut off the injectors one by one and pin point which injector is causing the noise. I haven't seen any mechanical engine problems with pistons etc. I have had one 01 with a tick from loose rocker(but that truck had been worked on by a dealer in Texas that caused the valve problem). Hope this helps, also I have had previously replaced injectors do this and usually replacing only that one corrects the noise.

[bear8236]

Thought this might help someone else, turns out that #8 injector was to blame. Was running -7mm3 i think it should be -4mm3? Anyway, #8 replaced at no charge to me, back on the road once again.
Thanks for all the replies on this.

[BradL]

My '01 has the knock as well, usually when it's very hot - as it has been in Houston for some time!