Hummin Cummins

Yep, I am having an intermitten chirp noise.

Seems to do it most often on a slight throttle load.
It does chirp when on easy acceleration (IE: going through the gears) and when driving up mild hills (as in when you give 'er more fuel with the throttle) to maintain speed.

The chirp or tweet does have a consistant rhythmn.
It also seems to come and go, but is more consistantly there than not.
It also coincides with the "popping" noise of the engine which I always assumed was fuel ignition.

When you are off the throttle or coasting it doesn'y do it.
When you are hard on the throttle it doesn't do it either.

I replaced my fuel filter 13500 miles ago, and am scheduled to have it replaced again at the next oil change (in 1500 miles).

(side question - when they replace the fuel filter would a bad lift pump show up?)

Any thoughts?

bulabula

How many miles on the serp belt? What shape is it in?

Some folks have been reporting belt failures, maybe yours is pending ..... (fortunately my belt is ok).

handymantim

My guess is that you're hearing the turbo. Do you now have the windows down now that it is spring and the weather is warmer? Based on when you hear it in relation to the throttle, I think it's the turbo you're hearing.

You say it's "constant" which to me would eliminate the fan belt. I was originally thinking it was the fan belt (i.e. A/C clutch kicking on/off) but since it's constant it eliminates that theory.

Hummin Cummins

No, not a turbo whistle and the popping isnt the pop between shifts.

I think it may be an injector, valve or lift pump.

It has a repetitive chirp.

I "always" drive with the rear slider open, so it is a new noise which coincided a few weeks after removing the turbo muffler from the intake tubing (that thing in the 9" long x5.5"dia round portion between the two rubber elbows). I checked for leaks.

Now for the last two days it hasnt done this chirp/tweet until last night. Then it did it pretty consistantly.

handymantim

I wonder if any debris fell into that turbo while the intake tube was off. Obviously I hope not but it's something to consider.

Hummin Cummins

No, nothing went into the turbo.

The noise started a while later, like 2 weeks later.

Wasn't immediate.

But the other noise that now coincides with the chirp/tweet...I call it the popping noise has always been there since day one.

I think something is wearing or on the fringe of failure.

handymantim

Are there any trouble codes?

Hummin Cummins

IT went away with this.

I noticed the weld that holds the downpipe support arm to it's iso mount was weakening. That hopefully was the culprit. I didnt notice the chirp/tweet last night.

https://www.dieseltruckresource.com/...threadid=67142

ChrisM55

my brothers did that when one of his intercooler hoses was loose. Double check all of those

Chris

Hummin Cummins

Hmm.

Thanks for the little tip.

I will go over those today just to make sure the new exhaust isn't covering up what use to be an occasional soft tweet/chirp.

I havent noticed it since installing my new exhaust however.