New injectors and still awful knocking???

[Classicfordguy]

Well I just finished doing new injectors, glow plugs, return lines, turbo oil return gromet and valve cover gaskets and the awful knocking noise is still present.

The noise has been there for the two years I've owned the truck and has always been a bit more noticable when the truck is cold and on high idle, it used to be pretty quiet then I did a 2000 mile trip to indiana and back and the noise got pretty loud. It sounds too heavy to be a valve or rocker noise sounds more like a wrist pin or something. The knocking will sometimes go away completely for a few seconds both at idle and driving.

I have no idea what it could be, is there any way it could still be an injector, like the IP isn't pushing fuel to one injector? Is there a way to tell if all 8 are realy firing?

I would think if it were something mechanical like a rocker or wrist pin the problem would have gotten much worse much quicker but that's just a guess, I'm realy to young to know how to diagnose all the bad sounds engines make. I've put about 1300 miles on it since it got bad all the while thinking it was an injector.

Any thoughts on what this could be or what my course of action to figure it out should be?

Thanks again for your guy's help,

-Rob

 

[Ironman03R]

It's a diesel its supposed to knock

Have you tried to loosen each injector line to see if the noise changes?

 

[rubberfish]

Have you tried to loosen each injector line to see if the noise changes?

And did you do this before you changed them?
If you did, you'd be able to tell if the knock moved or not.

 

[Classicfordguy]

Yup, I did try that before I ordered the new injectors. I could not pin the noise down to any one injector, only difference in the knocking noise was the engine idling slower due to the line I was cracking.

-Rob

 

[GenLightening]

Did you have the timing checked before or after the injectors?

 

[Diesel JD]

You mentioned that it was much worse cold or when the high idle advance it on, to me that suggests your timing is much too far advanced. Getting the marks lined up may not be good enough. The wrist pins have occaisionally been a problem on the 6.9s, usually nothing breaks but the motor makes a lot of noise, gets weaker, gets poorer mileage. I would:
1) Check the timing with tools and get the timing close to 8.5*BTDC with the pulse method or 1-2*ATDC by the luminosity method
2) Do an oil sample. This will tell you if there are any suspicious wear patterns on your engine...will NOT confirm or rule out a problem 100% sure. But it may give you an idea of what's going on.

 

[One_fast_IDI]

well i had this same problem just not as long as u have had it, but it was an injector for me. Mine knocked when cold and go away when warm. so i change injecrcors. I put new Delphi G Code's in and noise got real bad, though the motor was toast, did some calling around and every one said it sounded like an injector(just one). well i could tell which bank it was coming from so started swapping out the new injectors with old ones(that i knew were ok) found #7 injector was bad, replaced it and no more noise. Hope this helps you out.

Scott

BTW this just happened last night and got it fix to day so this is all pretty fresh in my mind

 

[One_fast_IDI]

Oh ya i could not find the problem by cracking injector lines. You might also have a bad ip if it isn't delivering fuel to one hole. but not likely but possible.

Scott

 

[One_fast_IDI]

sorry one other thing make sure that u put all the copper washers in and didn't double any, up that will cause knocking sound also

Scott

 

[Agnem]

Did you test (or have tested) the new injectors before you put them in? Swapping them out makes a big assumption, that in your case you probably don't want to make. Definitely get the timing checked by somebody with the right tools that knows how to use them.

 

[Pipeliner_86]

I putting my bet on a wrist pin. I'm pretty sure that is what has been rattling in my 6.9 for the last 4 years. My "wrist pin" rattle gets quieter when the engine is under load, and louder when the engine is what I like to call free-wheeling (no load). Either way it has slowly been getting louder over the years, and I am wary to drive to far from the homestead. Good thing I just use my truck for wood hauling.

 

[Classicfordguy]

I'm kinda picky and tend to do everything myself so the truck has never been to a shop hence the timing has never been checked. I don't understand how timing is checked on a diesel, is there a tool I can buy to do it or should I just find a decent shop?

I got stanadyne G code injectors, the guy said they would be pop tested before he sent them out, that doesn't mean it actualy got done.

I was pretty careful about getting all the copper washers out and puting one back in.

Is there a way to tell if it realy is a wrist pin or just process of elimination? What all is required to just replace one pin and piston I assume?

Out of time today as class starts today for me but tomorrow I'll try retarding the timing a bit to see what it does. Is it rotate the top of the pump toward the driver side to retard? Do you just twist against the lines a bit or what? How far should I turn it?

Thanks again for all your input guys, still pretty new to diesels and building engines in general.

-Rob

 

[Classicfordguy]

Also, I already have a blackstone bottle so I'll shoot off a sample here pretty soon.

-Rob

 

[GenLightening]

The timing is checking the fuel pulses to the injectors. As the pump or injectors wear, the timing changes (advances or retards?). If you install new injectors the timing will probably be changed to some degree. I believe you are correct on the direction for retarding it, but not sure on how much.

 

[suv7734]

How much blowby are you seeing out the oil filler?