hey guys. my truck has developed a slight "knock" i'm calling it a knock, but it sounds like a loud injector. it only happens once i've been running it for about 20 minutes and it does it more in the upper RPMs around 2400 up to 3000 under acceleration. if i let off the skinny pedal and just coast the sound goes away completely so i doubt it's anything wrong in the engine. i had a buddy say it could be a bent pushrod??? what are y'alls thoughts on this? i have looked at <ACRONYM title="Injection Control Pressure">ICP</ACRONYM> levels and it's reading good, but i unplugged the sensor just to see if injector noise changed much and it tried to die then picked back up to idle and sounded about the same as before.

i changed the oil/oil filter and the CPR fuel filter last weekend. i still need to take the 100 micron fuel filter out and clean it b/c i haven't done that in a long azz time. could this come from fuel pressure dropping off or do y'all think its a pushrod or something? i did notice that the engine started "fluttering" later last week before i changed the oil and stuff. i say fluttering like it was missing. the truck idles fine, but sometimes it will start to lope a little bit then comes back to it's normal idle. any ideas on things to check is appreciated!!

i have not been able to look at <ACRONYM title="Injection Pressure Regulator">IPR</ACRONYM> and stuff yet. my fuel pressure is 70psi at idle, but i'm not sure how much it's dropping off when running down the road. thanks again.

 

How high have you had the pyro temp?

 

I'm gonna go with a mangled rod or three.... Found you an excuse to do a full build on the PSD Travis. Lol

But back on topic, I could see it being a slightly bend push rod but I wouldn't jump there yet. I would check the IPR and if you can get a guage hooked up to your fuel system to be able to watch fuel pressures to see if they drop off. This is just a guess mind you, but I would think that fuel pressure dropping off a good amount would give you a slight knock as it was running out up top.

 

I'd check fuel pressure at WOT first. See if it's dropping off and causing your injector knock. A bent rod is bent all the time. A fuel restriction shows up only under heavy load at first.

 

i will set up a fuel pressure guage sometime this weekend and see what it is, but really i'm actually scare to pin the throttle right now as i can't afford to blow this thing up quite yet. haha. its not done with its working life, but it is getting closer. i will check fuel pressure and IPR % whenever i can find a tool to check them. on the other hand i will go ahead and pull the valve covers this weekend to make sure the pushrods are straight. might even change the IPR just for fun(my buddy has a spare)...

at idle its really starting to sound like the injectors are getting louder than they used to be. its almost like it's doing funny things with the HPO.. and wonder if the pins on the CPS could cause injectors to do this??? i'd think it would just kill the truck first tho. i haven't put grease on the pins of the CPS yet and i think they are different materials(silver vs gold???).

i'm trying to think of reasons to NOT put my new heads, chromoly pushrods, and studs on the truck, but it is really tempting to go ahead and put my ported heads on there so i know my valves are good, valve springs are good, chromoly pushrods won't bend, and headstuds for fun. LOL

 

Well i'm back to driving the dodge tomorrow. my slave cylinder blew up so i gotta get another one tomorrow. i hate not driving my truck... the 6.7 cummins just doesn't do it for me.... the dual mass flywheel is dumb and the way the throttle works is strange in that it takes a second or so to acknowledge your asking for more fuel..... So nobody else really has an idea on this one???

 

Sorry Travis, I don't have anything else for you. I'm sure you already did this but did you run your symptoms by Cody to see what he had to say on the subject? After being told that I had to drive a chuggins i would be puttin them heads on there just to make sure I didn't have to do that again, lol.

 

From what you say it sounds like a fuel knock to me. Problem is that I don't really know how to test for it. Check fuel pressure for sure. I doubt your CPS has any thing to do with it. I have been running gold/tin mixed CPS for a couple years with no issue.

oh and I also highly doubt push rods. They would not change in decel and they would be constant though the RPM range just might get louder and faster with RPM

 

nah, i haven't run it by cody. He probably wouldn't no wut to tell me anyways, but then again he could know something i guess. might ask him this weekend sometime. i think that it's probably a pushrod or a lifter.. hopefully not a lifter.....

 

its definatly those injectors......................................... send them to me!!!! lmao

 

I think its summer air in the tires!
Better hurry and put the winter air in!

LLIB----P3K

 

Tim, thanks for the reply man. i will find a way to check it. i could always ask Jim what he thinks about it.

i could hook a guage up on a line running off my regulator. i have an extra guage already, just gotta get fittings to do it. that will at least tell me if i'm losing fuel pressure.

but they have winter air in them???? should i be rotating the air more frequently???? haha. pulled that trick on a kid once and he actually believed us. that was high skool fo sho.. funny stuff there Bill. so y'all think it's just a fuel knock and i have guys on PSN who think pushrod.... Luckily i have spare heads, pushrods, and i will be pulling the post fuel filter today or tomorrow to check it if it stops raining for like 10 minutes. haha. thanks for the input guys!!!

 

Iam with Tj, not psn.
Does the power feel like it falls off at/during the knock?

Bill

 

negative. it keeps pulling strong under WOT. i didn't drive it today b/c the slave cylinder blew up on me last night, but when i got home i started it and let it run for about an hour. had my brother free rev it to 3k rpms and fuel pressure dropped to about 60lbs. if you don't floor it on free rev then it doesn't drop at all. i sent Jim an email asking him his thoughts on the injectors side. hopefully these aren't screwed up too.... haha.

i'm going to drop the money on a scanguage from Jim so i can do buzz and CCT tests and see IPR %. hopefully these things will come in handy!! haha. again, thanks to everyone for helping me with this. i have never hurt an engine internally(pushrods, lifters, connecting rods, etc.) so i didn't know what the bent pushrod or lifters would sound like. hopefully we can get this figured out.

 

I hope its nothing to serious travis. But then again I guess its part of owning these trucks, the hassel of fixing them. But I hope and pray its something simple, dont want you to drop alot of money when you got bills you could pay with that money.