Injector knock?

[Got HO?]

I know this has been discussed before, but I can't find the thread. My 2003 HO has recently got a lot noisier at idle (38k miles), and about 4 days ago developed an intermittent knock that is very distinct when idling in Drive. In neutral it is much quieter. Sounds like an injector on an old Mercedes 5 cylinder nailing badly. Truck has to be properly warmed up (at least 30 miles from startup) for the noise to be noticable. I was wondering if I have a loose injector or a bad one. Anyone remember what the outcome was of the other thread? Just changed the oil (no difference) & the fuel filter is 5k old. Tried some Power Service on the last fillup, no difference.



Thanks

 

[curatchko]

Yup, same here. Exact same scenario. Loud knock at idle, in drive. Neutral, it's quiet. Very slight pedal from a light and it happens too.



This is all new within I'd say the last 1000 miles.



The plus side, is that there are no performance issues, mileage and power are good, and no smoke or anything odd.

 

[OHale]

I had the same thing two weeks ago right after refueling. I went on a long trip in the mountains and the knocking was very loud. It sound like a loud gas spark knock.



I made an appointment to have it looked at. At the suggestion of someone on this board I refueled with a diesel fuel additive (Rotella DFA. ) For whatever strange reason by the time my appointment came around for service the noise was gone, except for being able to detect it faintly under load.



One thing I did do is when it was knocking badly at idle and in gear: I put the parking brake on, the transmission in drive, chocked the front wheels and put my thumb and index finger on each fuel line. The #1 injector line was making a hammering/clicking pulse and the other 5 weren't. When the noise went away so did the line hammering.



I told the Dodge Technician about it and he wondered if the line might have been 'air-bound. "



Hope some of this info is useful, beats me what is happening.

 

[yycguy]

Hi, as "ohale" said when mine started knocking a local shop suggested Howes Meaner Cleaner. I dumped it in and drove around and that cleared it up about 99% now just very occasionally I get a slight knock.

Hope that helps

 

[aggieLR]

I think a lot of it has to do with diesel quality. Mine was doing the same thing when we left Denver, CO and it did it on throught the whole tank, but much much worse with a load. It sounded like a gas spark knock, but after the next fill up, it completely went away.

 

[rbattelle]

Check out this thread.

 

[Got HO?]

Update

My noise is gone Oo. I guess it must have been some debris partially clogging an injector nozzle. I ran some Stanadyne fuel treatment through 2 tanks & the noise gradually disappeared. Sounds like it should now.

Hmmm, does this mean I should consider a better fuel filtering system?

 

[JVolpe]

Mine started about 600 miles ago. I had the TSB 18-037-04 done in hopes it would solve the problem. It didnt. I added Stanadyne Performance diesel additive on last fillup. Have about 200 miles on now and still have the knock/noise at idle. I think I even here knock with slow acceleration from about 1500 rpms, hard to tell with Banks exhause. I will put the additive in next tank and see what happens. If it doesnt go away it will take in to dealer. I already know the respnse, its a diesel and suppose to sound like that. I know that noise I hear now was not there for the first 8000 miles on the engine.

 

[Ron Civita]

Had the same problem. At 7,000 miles knocking began. At idle, in drive. Used Hammerdown #1500 diesel fuel conditioner and in several treatments, knocking disappeared and engine has been very quiet since (now at 10,500 miles.

 

[curatchko]

Mine is gone also. I am finding that it's related to where I get my fuel... I think fuel quality is the prime factor here.

 

[Badunit]

I have read a few times that the hammering on line 1 is normal and unrelated to the knock. On mine, lines 1 and 6 both hammer and I have a knock. The injector kill test didn't show anything so the dealer didn't know what to fix and sent me home.



So my question is --- Do those of you out there without a knock have a hammering #1 fuel line?

 

[OHale]

So my question is --- Do those of you out there without a knock have a hammering #1 fuel line?

Yes, I do. After a fuel up about a month ago I got the knocking. It sounded more like an intense spark knock from a gasser. It was not perfectly rythmic like a mechanical issue but had the random pattern similar to gas spark knock.



It was loudest at normal operating temperature and quietest at cold start up.



It knocked loudest in drive so I put on the parking brake, chocked the wheels and left the truck in drive. I got out and felt the lines and # 1 had a sharp pulse in it. The other lines were OK.



At the recommendation of a fellow TDR member here I ran Rotella DFA through the next two tanks and the knock is almost gone. It has come back a little after the last refuel. I spoke to the dealer Technican about it and he wondered if it had been 'airbound,' although I don't know how to apply that concept here.



Still mystified as to what exactly is happening. As someone pointed out here it does seem fuel-related.

 

[ttreibel]

I had one with about 7K on the truck 1 1/2 ago I dumped in a whole bottle of Stanadyne and it cleared it right up and has never returned. I use 1/3 bottle of Stanadyne every fill up you can't be to careful with these 3rd Gen fuel systems.