Pinging/knocking after injectors!?!

[Bighorn]

Update;

The injectors are new. The owner just text me and said it knocked at first when reving, but once it came up to temperature, the knock went away. Injectors are not the problem. I’m thinking piston slap

Wait a second here.. Does the owner know of the cold advance on these diesel engines.
Mine is loud too until it comes off the cold advance solenoid.
That is normal for indirect injection engines with a cold advance system.

What happens after the idle kicks down and it warms up?
If it runs fine, you have done your job and have nothing to worry about.

Edit: you reminded me of something Dr. Lee Swanger wrote in an article to the Diesel Page which I will read but paraphrase here so as not to plagiarize.

The last thing you notice after performance upgrades is that your engine sound may be "quite different" when you have it running again.
Starting will be different.
Higher pop injectors may make combustion sounds "sharper".

Anyhow, the actual text is on page 52 of the Diesel Page booklet titled 6.2 Diesel Engine Improving Performance and economy.

Maybe there is something wrong or maybe just different.
If the truck runs fine other than a different sound at startup, but operates normally after warm up, maybe it IS fine.

 

[Action]

What?

Ever since you worked on my car, it has been shaking real bad.

 

[HETvet]

Bighorn; these injectors are new stock replacements. This knock/pinging only started after I replaced the injectors. And it also not occurs off throttle (rev down) after reving up (1/4 or more throttle you input). I didn’t even suspect cold advanced due to ambient temperatures being 90 plus degrees. And the noise goes away once the engine coolant starts to come up to operating temperature. Yesturday ambient temperature was about 87-93 degrees with very high humidity. It was a hard, extended cranking period, but the engine fired. It still was making the noice, but no where near as bad as first fire up after the injectors were replaced. This morning ambient temperature was in the 55-60 degree range. It again was long and hard cranking cycles (2 cycles of the starter) before if fired up. It smoked more, and made the noise, but was even less than the second and third fire up after the injectors. Due to high ambient temperatures, and the pinging/knocking noise being made during the entier run cycles (5-15mins), I didn’t even think cold advanced.

Due to the long, hard starting issue, I believe the mechanical fuel pump has failed or is about to fail. He customer/owner bought a new one, but it didn’t have the port for the geared hub/differential breather tube. I personally don’t want to fight it to replace it as well. So I have a 30gallon per hour, 4-7psi electric fuel pump that I’m going to install and remove the mechanical system all together. Just haven’t done so yet. Given this trucks intended use is a hunting vehicle for elk hunts up in Colorado, we need to come up with a cost effective and reliable way to increase air flow and volume in to the engine to over come less dense, thin air at altitude.

 

[HETvet]

Action, you must be mistaken. I’ve never met you in person, haven’t lived in Florida for over 12 years, and never worked on your car. Sorry for the confusion

 

[Bighorn]

Action was making a joke.
But glad to hear the problem is diminishing.
As for altitude, mine starts and runs fine at 8,990 ft.
N\A 6.2
Good luck.

 

[Action]

I thought your "what?" Was asking about the dver since customer, so i described one.

How are the glow plugs? Is the tip of one bouncing around?
Just above, you stated the sound only started after you replaced the injectors.
I think on page 2, you said the customer told you it was doing that before you got it????

 

[diesel dave]

I agree with bighorn and action. Hard starting is almost always due to glow plug issues. And the cold start advance doesn't care what the ambient temperature is. Until the engine reaches operating temp,its "engaged" and the engine will ping-knock. And you indicated the owner said the knock goes away once warm. Not saying these are the answers. But from what you have described,this is where I'd be looking before throwing anymore money at it.

 

[HETvet]

I don’t see, personally, how a Diesel engine with 18-21:1 static compression would even need glow plug in 90 plus degree weather. Not saying I’m disagreeing with any one. Just stating my opinion. My gut has been saying fuel issue. I could be wrong, wouldn’t be the first time.

Because I’m clueless, how does the coolant temperature sensor communicate with the injection pump/cold advanced solenoid? Meaning, is the coolant temp sensor a resistor and when cold the injection pump sees 0v or 24v and as the coolant warms up, resistance increases/decreases?

To test this I could disconnect the IP from the coolant temp sensor and listen to see if the pinging gets worse or goes away?

 

[doghead]

It needs glowplugs because it is what is called an indirect injection diesel engine.

By design, it needs them.


https://en.wikipedia.org/wiki/Indirect_injection

 

[Bighorn]

I don’t see, personally, how a Diesel engine with 18-21:1 static compression would even need glow plug in 90 plus degree weather. Not saying I’m disagreeing with any one. Just stating my opinion. My gut has been saying fuel issue. I could be wrong, wouldn’t be the first time.

Because I’m clueless, how does the coolant temperature sensor communicate with the injection pump/cold advanced solenoid? Meaning, is the coolant temp sensor a resistor and when cold the injection pump sees 0v or 24v and as the coolant warms up, resistance increases/decreases?

To test this I could disconnect the IP from the coolant temp sensor and listen to see if the pinging gets worse or goes away?

The odd element to all this is that, correct me if I am wrong; you are saying the "knocking" is gradually going away on it's own.
That is the opposite of what would happen if the lift pump was going bad.
How many stops and start cycles are we talking about here?
Personally I would take that puppy out on the highway and drive it like.. 100 miles or something.

Anyhow, I live in an arctic climate.
So my 6.2 is always on it's cold start, high idle (two different things) after starting.
But I know, as long as it is on high idle, there is a definite "ping" and "knock" if I try to drive it around.
Once it drops off the high idle, the injection pump also de-advances and the "knock" is gone".
When I say high idle, I mean the throttle kick up solenoid and that is external to the injection pump.
But there is also a cold advance going on inside the injection pump that advances injection timing enough to make a racket.
Like magic, as soon as the idle drops back to warm idle, the knock is gone, no matter how I mash the throttle.

Maybe you do have a problem.
I can't tell from here.
Just wanted to let you know there is a phenomenon associated with the system that produces a normal "knock" under certain circumstances.

 

[HETvet]

It needs glowplugs because it is what is called an indirect injection diesel engine.

By design, it needs them.


https://en.wikipedia.org/wiki/Indirect_injection

I get it. The precombustion chamber gives the swirl and high velocity of the intake charge. Low pressure fuel is injected and combustion happens. The flame front expands out of the precombustion chamber, across the cylinder, then down as it pushes the piston down.

But when you compress .77 liters of air in to a precombustion chamber that might have the volume of maby a tea spoon, the compressed air temperature will combust DF2; there is no way the heads have that kind of thermal efficiency. Not trying to argue, and I’m not going to.

I ran it till it came to operating tempature and verified the noises were gone. With the engine running, I disconnected the injection pump from the temp sensor. Noise came back. Re connected them; noise went away. It’s cold advanced. In my life I’ve never heard a healthy engine knock/ping as loud as this thing does cold.