Knocking noise

[Jdonoghue]

Sounds like a rod knock. It's been doing this for three weeks though, I just couldn't 'pick' the noise out over the other noises (road noise, open exhaust noise, other 'old truck' noises). You can hear it at idle, and through the entire RPM range. It is louder when there is a load (raising engine speed slowly=knocks louder, engine decelerating=knock is not there). The injectors are fairly new - still shiny, etc. but I don't know where they came from or what kind they are. Just that they were replaced before I bought the truck. But I would think a bad bearing would have toasted itself by now. Any suggestions?

 

[Grey Wolf]

Have you drained the oil to see if there was any bearing material in the oil?

 

[Jdonoghue]

Originally posted by Grey Wolf

Have you drained the oil to see if there was any bearing material in the oil?

That's what I'm going to do when I get home from work tonight.

 

[Jdonoghue]

Haven't drained the oil yet to check it. But I noticed if I raise the engine speed a bit, it 'shakes' a little. Is it possible one of my so-called 'new' injectors is bad and causing the knock?

 

[Grey Wolf]

I would say that could be a possibility, especially if it has air in it.



Try cracking one line at a time to isolate the dead hole.

 

[Jdonoghue]

I drained some oil into a clear plastic pan - don't tell my Wife and went looking for metal powder/shavings/flakes/etc. Couldn't find anything. With some careful listening I can tell that if I crack the line to #6 injector the noise appears to go away. Also, the engine RPMs don't seem to drop as much as if I crack the line to any of the other injectors. Could it be dripping/leaking fuel into the cylinder, causing a really bad knock? The injectors are supposed to be new - they are shiny, no rust or paint on them, and they have four holes (I remember from when I had the head off), I don't know if they are stock.

 

[Grey Wolf]

I would say there is a good possibility that you have found your problem Can you take the injector to a shop near you and have it pop tested? Better yet take them all in and have them checked... ... ... Just remember to keep number six separate to confirm your suspicions.

 

[phillips5]

Yes he can Take them to Blisfield systems and let them check them. If money is an issue they mite check one and give you an estimate for free. I have a pop tester we could check them our selfs. I do think you found the problem.

 

[phillips5]

The place used to be called Blissfield Fuel Systems now I think it is North West Fuel Injection. Or something like that.

 

[BushWakr - RIP]

Have them balanced and spray pattern checked then reset to another 5 bar (over spec) opening pressure.



pb...

 

[dpuckett]

4 holers

In my experience, the stock tips had 6 evenly spaced holes in them for IC trucks; 4 holes, not so evenly spaced, for nonIC. I've never had an injector make a knock before, but have had some carboned up pretty bad, squirting like a Windex bottle on stream, that make for sucky MPGs, along with lots of smoke.



Pastor, if he gets the pop pressure set 5bar higher, how much timing advance does that equate to, as the higher pressure will have a net retard on dynamic timing? Or is 5bar not enough to worry about?



Daniel

 

[CDegner]

If the pressure is set higher, that would equate into retarding the timing slightly.



Higher pop pressure = fuel being injected slightly later.



The only benefit I can see to this would be better atomization. PB, is there something I'm missing?



and a out-of-balance injector will definitely cause a knock.



Carl

 

[Lnwing]

I have no idea whether this can happen with the VE pump, but I had an industrial engine develop a knock, especially under light loads and lower rpm. The cause turned out to be not injectors, but a loose set screw in the pump (Simms in-line) which allowed one cylinder to receive full fuel while the rest were at idle. Talk about a racket!

FWIW

 

[Jdonoghue]

2nd opinion...

Starts good, runs good, the noise is nothing to be concerned about. I really thought I had one cylinder knocking. But it's OK, and can go back to driving it but I really feel like an idiot now!

 

[dpuckett]

It woudl still be worth it to pull the injectors and get them tested. If you drive it hard enough with a squirting injector, you can burn a hole in a piston , esp if you have PODs, as suspected in the other thread.



Dont get me wrong, Carl, I by no means was arguing with injectors making a racket if they were out of spec or unbalanced; just saying it was one of the seemingly few maladies I have no personal experience with.



-DP

 

[Jdonoghue]

Originally posted by dpuckett
It woudl still be worth it to pull the injectors and get them tested. If you drive it hard enough with a squirting injector, you can burn a hole in a piston , esp if you have PODs, as suspected in the other thread.

Dont get me wrong, Carl, I by no means was arguing with injectors making a racket if they were out of spec or unbalanced; just saying it was one of the seemingly few maladies I have no personal experience with.

-DP

I may still do that. They're supposed to be new, they're still shiny. The numbers on them aren't the same as the other POD injector numbers I've found searching through the site. I still wonder exactly what they are, the only thing the PO told me when I bought the truck is that they were some kind of marine injectors.