Engine noise (injector?)

[540s10]

I have a noise that sounds like a rod nock, but it is definately not a rod knock because I put new bearings in, thinking the noise was a rod knock (it needed bearings anyways so im glad i did them).

I have also ruled out the; harmonic balancer, crank pulley, vacuum pump and any other accessories and any noise made from physical contact on the outside of the engine block

(im not going to do the troubleshooting guide because 99% of it doesn't apply)

truck has 294k miles on it AFAIK its still the original motor

No real noise when cold, only after running for a few minutes.

at idle the noise is NOT consistent with cylinder stroke (maybe 1 knock then 2 a few seconds later then 1 in another few seconds)

the knock does not always have the same tone (it may be soft a few times in a row, then one loud knock)

When the knock is its loudest at idle the engine shakes like a 1 cylinder misfire. (engine runs smooth when not knocking, shake is more pronounced the louder the noise)

Knock is consistent at 2000rpm (no pronounced vibrations or engine shaking)

there is some white or light blue smoke from the exhaust

Also NO SES codes



I bought the truck not running so I do not know when it may have started making this noise.

I am leaning towards a bad injector at this point. Is it possible with a crows foot wrench to loosen the pass. side injector lines after removing the heat shield?

 

[bk95td]

That sounds like a injector sticking to me. I've never tried removing the injector lines without removing the turbo. From what I've read chris1500 was quite good at changing injectors without removing the turbo. Send him a pm. He may be spending his time in the d-max section now.

 

[SmithvilleD]

Is your thought to loosen one line at a time to isolate which injector?

You can get a crowfoot on the inj line nuts, some angles require or at least work better with a wobble end extension.

I'm not as familiar w/ the OBDII trucks but BK95TD may know - will your Tech 1A allow disabling 1 injector at a time? Or show any of the cylinder imbalance action/compensation?

If the stumble/knock happens consistently enough, you might even be able to locate it w/ a mechanic's stethoscope or long screwdriver up to the ear - touching each injector.

 

[Turbine Doc]

When you did the bearing change did you inspect that rockers are still engaged, plastic retainers wear out, with your miles even if that's not it, and you haven't done so already mite be worth checking out noise did not change after rod bearing swap ? same as before the swap? if you don't have scan tool, at 294K and if original injectors, those are "long in the tooth" depending on how driven consensus @ 100K you need to start considering fresh set of injectors or having them cleaned/tested

 

[Missy Good Wench]

Definately sounds like you got a bad squirt in the bunch.

Loosen the lines one at a time or get a scan tool that can shut off each cyl one at a time.

Bad injectors can make a buttload of noise for sure.

 

[540s10]

When you did the bearing change did you inspect that rockers are still engaged, plastic retainers wear out, with your miles even if that's not it, and you haven't done so already mite be worth checking out noise did not change after rod bearing swap ? same as before the swap? if you don't have scan tool, at 294K and if original injectors, those are "long in the tooth" depending on how driven consensus @ 100K you need to start considering fresh set of injectors or having them cleaned/tested

Judging by the rust on the injectors and how it matches the rust on the head, I wouldn't doubt them being original...PO said all service was done at the GM dealership, so I'm hoping the the VIN check I requested will shed some light on things. The only parts of the truck I KNOW have been serviced are the transmission (goodwrench replacement decal on it), The IP has a green tag on the corner of it and has been marked for Timing adjustment, and there was a fairly new DELCO reman starter on it. It really doesnt sound like one of the rockers not working or falling off, but I'll keep those plastic locaters in mind next time I have the injector lines off.

Definately sounds like you got a bad squirt in the bunch.

Loosen the lines one at a time or get a scan tool that can shut off each cyl one at a time.

Bad injectors can make a buttload of noise for sure.

I ordered a scan tool last night, figured I could use it on the rest of the fleet as well.... I also ordered new injectors, figured wth it prob needs em anyways judging by how they look.

 

[fonecop1]

Does it sound like a hammer hitting concrete? If so it's probably an injector and they say not to mess around with one of these because it will burn up a piston. Mine was sounding like that and I changed the injectors and that cured it.

 

[Matt Bachand]

Hey, is the truck in Shrews? Lets find a good time for me to swing by and hear it, or you swing by my house if its mobile....

You can crack injector lines with a normal wrench, Crack each one and see if noise goes away, or if noise doesn't go away (assuming noise/smoke gets worse with each other one cracked)

I had a valve failure last winter, so I went through alot of this, also had injector stuck open issue... also have a diesel compression tester I forgot to tell you..

I'll be around most of tomorrow as i'm getting rained out of work, working Sat to make it up, and free Sunday also (except for patriots game of course)

 

[Matt Bachand]

I also have a few old but working injectors if you'd rather just swap one for one if you suspect a bad one.

 

[540s10]

Hey, is the truck in Shrews? Lets find a good time for me to swing by and hear it, or you swing by my house if its mobile....

You can crack injector lines with a normal wrench, Crack each one and see if noise goes away, or if noise doesn't go away (assuming noise/smoke gets worse with each other one cracked)

I had a valve failure last winter, so I went through alot of this, also had injector stuck open issue... also have a diesel compression tester I forgot to tell you..

I'll be around most of tomorrow as i'm getting rained out of work, working Sat to make it up, and free Sunday also (except for patriots game of course)

it's not on the road just yet, i may get at it tomorrow if i feel ambitious, my father was home today and had me start it, he said its makin the same noise his old trucks did when the injectors went out so that gives me a little hope. I'm gonna soak everything tonight with some pb in prep for removing stuff. I have your number so if I need a hand with checkin anything out ill give ya a ring... My scan tool stuff (early birthday present ftw) may be here soon as well, so i might just wait and diagnose it the easy way haha. I still have to replace the rear brake line (figures the only real rust on the truck was on the rear line next to the tank and it let go) so I may end up doin that this weekend instead.

 

[bk95td]

My tech 1 will do the cyl.balance on obd1. I don't have the obd2 adapters for it. Gmtdscantech will do cyl balance on obd1.

 

[540s10]

PRELIMINARY DIAGNOSIS-

went to loosen the injector line on #2 and the thing spun right around, with no effort..... Looked closer and the whole injector was spinning with the nut, put a wrench on the injector top to hold it, loosened the nut off the top screwed the injector in as much as i could with the wrench (still not tight)... started the truck up and the loud knock and misfire associated with it went away as well as the majority of white smoke from the exhaust...

could all this be from the injector being loose?

im going to try to swap that one over to the other side and see if the noise goes away or just follows the injector.

 

[Matt Bachand]

PRELIMINARY DIAGNOSIS-

went to loosen the injector line on #2 and the thing spun right around, with no effort..... Looked closer and the whole injector was spinning with the nut, put a wrench on the injector top to hold it, loosened the nut off the top screwed the injector in as much as i could with the wrench (still not tight)... started the truck up and the loud knock and misfire associated with it went away as well as the majority of white smoke from the exhaust...

could all this be from the injector being loose?

im going to try to swap that one over to the other side and see if the noise goes away or just follows the injector.

Excellent news.... I got a couple old but working extras.............

 

[540s10]

UPDATE--

took fuel injector out of both #1 and #2 cylinders

swapped places

started the motor... noise significantly quieter whats left of noise moved to the drivers side with the injector, loosened injector line on #1 (supposed bad injector) and noise went away... there is still some noise, but I'm gonna say its the other injectors being worn, and just the clakety clak these motors make.

also pulled these numbers off the injectors--

'BOSCH GERMANY 068-3 0430211097 and 973 in large numbers' they also had steel nipples as opposed to the plastic? on the new ones? are these the OEM injectors or must they have been changed once?

Found this on the "good" injector that i swapped, looks like the spray pattern is fubar as the carbon is wash off of the area outlined... its not wet tho so it wasn't leaking--

 

[540s10]

New Bosch injectors are on the way from RockAuto courtesy of Matts link and discount code hopefully ill have them by next weekend.

 

[Matt Bachand]

New Bosch injectors are on the way from RockAuto courtesy of Matts link and discount code hopefully ill have them by next weekend.

You're should also get an injector install kit for the copper crush washers and replacing all those return lines with clampless style good idea too.

I got mine on E-Bay for 25bux from Tim at Accurate Diesel. Tim seems like a good guy who personally takes a little pride in each order.

Let me know when you need the inj socket... I wouldn't even try it without it, unless you plan on removing the turbo with a traditional 30mm socket.

The injector socket is thin walled, allows accomodation for 3/8ths ratchet for more work room, and has a 7/8 hex cutout on the back to get a wrench on it. Makes Pass side much easier.

Also good idea to just remove the wheel well from the passenger side fender, you can housekeep all the grounds, and makes injector swap a breeze.

 

[540s10]

im glad you mentioned the clampless lines as i was fighting with the clamps as i was swapping the injectors. I ordered that kit today truck should be good to go by the end of next week woohoo!

 

[Matt Bachand]

im glad you mentioned the clampless lines as i was fighting with the clamps as i was swapping the injectors. I ordered that kit today truck should be good to go by the end of next week woohoo!

Yep they suck.

Now you can just grab the return lines and yank them right off... If they don't want to just yank off, hold high tension on them for about 5-10 seconds until they come off... Don't even bother trying to undo those stupid things...

And on re-install, on 7 and 8 cylinders, you can put the cap and clamp on before you install.... Takes the suck fest out of that too.

some recommend neversieze on the threads, it will also help hold the copper crush washer on so it doesn't fall into the great abyss.

 

[540s10]

UPDATE------

new injectors came in yesterday, put them in today with the help matt's injector socket. Noise is all gone and it revs and idles super smooth. Took about 5 hours to get both sides done, passenger side was a piece of cake with the turbo removed.

 

[Matt Bachand]

UPDATE------

new injectors came in yesterday, put them in today with the help matt's injector socket. Noise is all gone and it revs and idles super smooth. Took about 5 hours to get both sides done, passenger side was a piece of cake with the turbo removed.

Great news! Sounds like a happy 6.5.