Too high of timing, effect low RPM sound? Injector Rattle?

[AMS247]

I posted up here a couple months ago, and in that thread I found that what ever was making the sounds that I didn't like was contributed by the new injectors that I had installed.

With these new injectors, it made a weird sound, only under load that I would have described as a similar sound to a gas v6 engine exhaust manifold leak. The sound sounded air related, maybe even like the valves were out of spec. I checked valves a few times and they are at perfect Cummins Spec.

I swapped back to the factory injectors that I had and everything sounded perfect in the engine once again.

I'm having trouble with hands on communication with the injector company that I've done business with and frankly I am a noob when it comes to this sound.

Right now, my truck has upgraded fuel plumbing, keeping 25 psi at idle and keeping north of 30 psi up to 45 psi while driving.

• 4k GSK
• S362 SXE
• 18* Timing
• O-ringed Head
• Hamilton Valve Springs and Pushrods

With the factory injectors, they have about 200k miles on them from what I know, and they do seem to be going out if I were to give my uneducated guess.

These new injectors are 5x14 SAC with the edge filter removed and needle work. New Bosch Nozzles on New Bosch Injector Bodies.

I sent them back to be looked at by this company 2 months ago and just received and installed them this week.

Anything below 1,800 RPM I can hear this sound in the cab very easily. Up to 2k I still hear it but it's not as prominent. From 2k to 3k even under load accelerating up a hill, the engine sounds perfect.

Is this just something to do with timing, and not the injectors themselves? I keep reading about Injector Rattle but I can't find a video to understand if that is what this is.

Is this a sound that I'm hurting the engine?

Also to add:

The engine starts up fine. In Park or Neutral the engine idles as the same RPM that the factory injectors Idled at.

Only when the engine is cold, do these new injectors drop to a lower RPM than the factory ones once I put the truck in gear with the first start up.

2 Months ago when it was much colder out (40-50*F) it would drop low enough to lope. Now (70-80*F) after I received the injectors back it doesn't lope, but does drop more RPM than the factory ones have been.

[SCHMITTY]

P pump 12 valve’s isles go up and down with the temp. Adding fuel will also change the idle characteristics. The injectors you installed probably have a different pop pressure and they may cause the differences your hearing also. These motors make a bit of noise regardless.

Who’s injectors ?
Can you hear the noise on video ?

[AMS247]

Originally Posted by SCHMITTY

P pump 12 valve’s isles go up and down with the temp. Adding fuel will also change the idle characteristics. The injectors you installed probably have a different pop pressure and they may cause the differences your hearing also. These motors make a bit of noise regardless.

Who’s injectors ?
Can you hear the noise on video ?

Video Clip:
12vproblem1 - Google Drive

Audio Clip:
Weird sound 6bt12v - Google Drive

I can't hear the sound in all speakers. And I need to have the volume up on my stuff to hear what I am talking about.

I guess is sort of sounds like a jake break while under load in the lower RPMs... I don't have an exhaust brake and it's only under load. If I let off the fuel, it sounds fine.

And, once I'm above 2,000, it sounds great.

Having the factory injectors in, with all the conditions exactly the same. This jake brake type sound isn't there.

As far as the company name I don't want to show that yet depending on if this situations IS an injector problem and they're lagging on doing something about it. Contact with them has been difficult but I'll PM you.

[AMS247]

The other thing that I will add. Is that I have noticed that shifting above 2,500 RPM with an unlocked converter the turbo slightly surges. This is at approximately 30 psi.

I do have a built auto with a FMVB. Lower stall converter so I would imagine it is just because of the drop in RPM. BUT, that is also a change that I had noticed.

[jasonc]

Worse case scenario if an injector is faulty/damaged, and the needle not sealing or stuck, it could cause a fuel knock or just a dead cylinder and skip.

What's timing set at?

[AMS247]

Originally Posted by jasonc

Worse case scenario if an injector is faulty/damaged, and the needle not sealing or stuck, it could cause a fuel knock or just a dead cylinder and skip.

What's timing set at?

Good to know that it won't do any damage to the engine running like this..

Timing is set at 18*.

[SCHMITTY]

How was the timing set ?

[AMS247]

Originally Posted by SCHMITTY

How was the timing set ?

Dial indicator on the #1 delivery valve holder.

[jasonc]

So in other words, you really don't know what the timing is set at.

Do you know how to set the timing off marking the balancer? Only really accurate way
I'll explain it if need be.

[Smokem]

The only accurate way is with a timing light.

[AMS247]

Originally Posted by jasonc

So in other words, you really don't know what the timing is set at.

Do you know how to set the timing off marking the balancer? Only really accurate way
I'll explain it if need be.

Would you be referring to putting a degree wheel on the balancer and using the factory pump pin to use as a base line?

I do have a magnetic degree wheel to do such. If that is what you're referring to. Is that more accurate than the dial indicator method off the pump?

I don't have a timing light.. if it's not too pricey I would be open to buying one to give it a shot.

I talked with the company today. They are sending me a new set of injectors with higher pop pressure to see if that is the issue.

The response in this thread from PDD is the only thing on the internet that I can relate this experience to without further detail.

injector pop pressure question - Dodge Cummins Diesel Forum

The injectors were checked for pop pressure when I sent them back and they all checked out within spec of each other. Maybe the pop pressure overall is too low? I do not know the current pop pressure's of these to add...

[jasonc]

All you need is a coat hanger wire.

Roll the engine until the pump can have the pin inserted, you don't even need the pin, just put the flat in the window.

Knock the pump gear loose.

Pin time the engine with the push in button that goes in the back side of the cam gear.

Make a pointer out of coat hanger wire and mark the balancer.

Divide the diameter of the balancer by 360 and make marks on the balancer for the amount of travel for timing advancement. Then back the balancer off to your new mark, good idea to roll the engine back farther then go back to your mark, to get rid of any gear slack.

Starting off with a base timing of 13, which most stock pumps are pinned timed at, or close enough.

Then torque the gear back on.

[Tate]

Originally Posted by jasonc

All you need is a coat hanger wire.

Roll the engine until the pump can have the pin inserted, you don't even need the pin, just put the flat in the window.

Knock the pump gear loose.

Pin time the engine with the push in button that goes in the back side of the cam gear.

Make a pointer out of coat hanger wire and mark the balancer.

Divide the diameter of the balancer by 360 and make marks on the balancer for the amount of travel for timing advancement. Then back the balancer off to your new mark, good idea to roll the engine back farther then go back to your mark, to get rid of any gear slack.

Starting off with a base timing of 13, which most stock pumps are pinned timed at, or close enough.

Then torque the gear back on.

To be fair, this isn't anymore accurate than using a dial, since you still don't know where you're starting from. You're just assuming base timing is at 13, and moving a known amount. So in the end, your result is just a guess. Same as the dial.

[jasonc]

I was assuming he has a stock run of the mill pump still, pin timing is around 12 or 13. These motors aren't smart enough for 1 degree of timing to matter at this level. So close enough.

[jasonc]

Way less chance of error setting timing off the balancer.

[CorneliusRox]

Originally Posted by jasonc

All you need is a coat hanger wire.

Roll the engine until the pump can have the pin inserted, you don't even need the pin, just put the flat in the window.

Knock the pump gear loose.

Pin time the engine with the push in button that goes in the back side of the cam gear.

Make a pointer out of coat hanger wire and mark the balancer.

Divide the diameter of the balancer by 360 and make marks on the balancer for the amount of travel for timing advancement. Then back the balancer off to your new mark, good idea to roll the engine back farther then go back to your mark, to get rid of any gear slack.

Starting off with a base timing of 13, which most stock pumps are pinned timed at, or close enough.

Then torque the gear back on.

This is how I do it! Just make sure to do a soft drive up to temp, then retorque the pump gear nut. I've had them come loose if not on multiple occasions. Oh and make sure the brake clean you clean the shaft off with is completely dry. I've seen them slip, then take it off, and find wet brake clean in there still... Much not have anywhere to go.

If they still have the rivited on tag on the timing cover, it'll call out what the pump was originally pinned to.

And anyone saying this isn't accurate enough... I would maybe agree if you had a race engine with damn near perfectly machined hard parts, but for most stuff, being 1-2deg off is going to be unnoticeable and might act different truck to truck.

I like to start at 21deg on a stockish truck, and adjusted it if needed.

[Smokem]

Originally Posted by CorneliusRox

And anyone saying this isn't accurate enough... I would maybe agree if you had a race engine with damn near perfectly machined hard parts, but for most stuff, being 1-2deg off is going to be unnoticeable and might act different truck to truck.

We verify injection timing with a light on the engine dyno before each session, it is very common to see the assumed value 5-8° low compared to measuring it at the injector. This is very important in a competition surrounding as 3° in the right direction can often yield in the neighborhood of 100hp. I can understand that this isn't an option for everyone, but to say that setting the timing via the damper is the only accurate method is quite naïve.

[AMS247]

I'll be waiting on the new injectors to arrive before I attempt to mess with the timing.

This engine's Cummins ID plate shows that it is pin timed to 14*. It was still safety wired when I received it so I'd guess that 14* is what the pump is still pinned for.

If the new injectors don't make a difference, I'll re-time the pump doing it as suggested above.

Pinning the pump at the 14* this engine came with, then going off the balancer. I have the magnetic timing thing for the balancer from PDD.

I know I've tried to push the TDC pin in on the back of the cam and have never been able to engage it. Weather the tip has broken or it's seized within the retainer i don't know.. but I've also read that the TDC pin for the back of the cam gear itself can have up to 3* of fluctuation?

If that is true, without removing the head would it be more accurate to do the drop valve method of finding TDC?

Working on Cylinder #1 and extending the intake and exhaust valves down to contact the piston on the piston's way up and looking for 0.001ish deflection in the dial gauge and using the middle of those two points on the damper to mark TDC?

[jasonc]

Originally Posted by Smokem

We verify injection timing with a light on the engine dyno before each session, it is very common to see the assumed value 5-8° low compared to measuring it at the injector. This is very important in a competition surrounding as 3° in the right direction can often yield in the neighborhood of 100hp. I can understand that this isn't an option for everyone, but to say that setting the timing via the damper is the only accurate method is quite naïve.

I understand, and don't want to spread bad info. But a normal guy with a mild street truck, who doesn't own a diesel timing light it's a decent option.

[BigPapa]

Originally Posted by AMS247

I know I've tried to push the TDC pin in on the back of the cam and have never been able to engage it. Weather the tip has broken or it's seized within the retainer i don't know.

Pull the pin out and check it. It has a little star washer looking thing holding it in. I used a pair of needle nose pliers, one jaw on each side of of the small part of the shaft and use the points to pry against the gear case. It pops right out. Do what you want with the retainer, i pitched mine. The friction of the o-ring’s been holding mine in for over 400K miles.