Engine/Transmission (1998.5 - 2002) What happend to this Injector.....

[JR2]

Here is the story, pulling a grade with EGT about 1150 - 1200 for 10 minutes. Truck develops a ticking sound and then boom, white smoke and she don't want to run... After a tow and some work (new injection pump and different injectors) she runs and runs good. So my question is what happend to the injector. It is not a stock injector and is about 160-180 hp over stock and has more holes than a stock injector. The injector in question was in the #6 hole.



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[KLockliear]

Those extra holes left too little material between themselves and done broke.

 

[Mundgyver]

I find the crystalline structure at the top seat point interesting when compared to the sweeping clean break below on the housing. . My question is, who made the injector or was it a re-manufacture. Stock injectors have 5 holes I think, at least my 2001 stock ones were that way, and a set of 275's will have 7 holes.



How many miles were on them

 

[JR2]

Keith - thats what we thought to, but if it was going to break would it not have broken at the holes and not have half the tip broken off?? I gues maybe a little piece could break off and then the (excuse the ingnorance on terms) pointy needle thing could break off more??



Mundgyver - The injectors where made my a fairly well known source and made from blank tips. I am not going to tell who made them with out permission from the guy who owns them because I don't want to cause problems between them. I will tell you that they are EDM's and not DonM's. I also think the structure you are seeing is an act of the flash of the camera and the fact that I cleaned the injector with WD40 before the pics. I will know more once the injector goes back to the maker for evaluation.



Lets keep the ideas coming.....

 

[Marco]

Blank tips?

Blank Bosch tips?



I've researched the EDM thing a long time ago. At that time the only blank tips available were Bosch units.



I've been warned that more than seven holes and the tip would break... . Only a sac hole would be possible...



So I assume what KLockliear sez is correct.



Marco

 

[willyslover]

so did it get shut down before the broken off piece did any major carnage ?

 

[JR2]

Gary-

Yes it did we think, actually the missing piece of injector is no where to be found and we are thinking it got exhausted out of the truck, either that out it now a permenant part of the piston.



JR2

 

[RustyJC]

If it rattled around in #6 and then went through the turbine wheel in the turbocharger, I fear you may well be finding the damage pretty soon.



Might be worth taking a look if you can find a fiberoptic borescope small enough in diameter to go through the injector hole in #6 - try some of the shops that service small (Allison, Solar, etc. ) gas turbines. For the turbo, I would probably split the case and take a look at the turbine wheel.



JM2CW



Rusty

 

[JR2]

Rusty -

Well that is what I thought too, but the guys doing the actually work so that in there experience the piece probably made it out and the guy that owns the truck is happy. My work has a 30 ft boroscope that would work, but its 800 miles away.





To Everyone,

These pictures and the questions posed where done just to try and figure out what happend to the injector, not to attempt to defame the injector builder. Pleae stop calling every EDM injector maker you know of trying to figure out who made them. We do NOT know for sure what happend and it is possible that the injectors where damaged in transit, or that the injection pump played a part in the failure (as it went kaput at the same time) or any number of other if's.



Thanks,



John

 

[RustyJC]

John,



I've worked for an industrial engine manufacturer in various technical and engineering capacities for 30 years. When something as small as a chip off an exhaust valve, a small washer, etc. goes through a cylinder on one of our engines, it will generally (as an absolute minimum) ding the piston crown, damage an exhaust valve face and seat, then ding a turbocharger blade (axial flow turbines) as it goes through. This will result in a compression leak at the damaged valve and seat, and usually we will see crack propagation on the piston crown and turbocharger blade(s). Given the stresses (thermal and centrifugal force) the turbine blade/wheel is subjected to, when it fails, it generally comes apart in a big way.



We have an old saying here in Texas - You can't help a man who doesn't want to be helped. If the truck owner is happy as of this 5 minutes, it's because he probably figures that what he doesn't know won't hurt him. Unfortunately, he's likely mistaken - I've seen very few engines heal themselves when they've been hurt!



Rusty

 

[KLockliear]

My GUESS is that this injector had extra holes EDM'd into it above and beyond the stock holes. This then makes the thickness between the new hole and the two holes beside it thinner and more prone to crack/break, which is why only one piece would be missing.

 

[R.ebel]

Originally posted by RustyJC

John,



I've worked for an industrial engine manufacturer in various technical and engineering capacities for 30 years. When something as small as a chip off an exhaust valve, a small washer, etc. goes through a cylinder on one of our engines, it will generally (as an absolute minimum) ding the piston crown, damage an exhaust valve face and seat, then ding a turbocharger blade (axial flow turbines) as it goes through. This will result in a compression leak at the damaged valve and seat, and usually we will see crack propagation on the piston crown and turbocharger blade(s). Given the stresses (thermal and centrifugal force) the turbine blade/wheel is subjected to, when it fails, it generally comes apart in a big way.



We have an old saying here in Texas - You can't help a man who doesn't want to be helped. If the truck owner is happy as of this 5 minutes, it's because he probably figures that what he doesn't know won't hurt him. Unfortunately, he's likely mistaken - I've seen very few engines heal themselves when they've been hurt!



Rusty

I agree with Rusty, it is very likely that the #6 cyclinder has been damaged and is down on compression. A simple compression check would be wise. I'd also take the turbo exhaust housing off and take a good look at the turbine wheel. JMHO

 

[Turbo Tim 1]

My thought after reading this, and it is only a half educated guess, but the boom had to come from somewhere, so how about built up fuel in the #6 cylinder because the injector had let loose. Now with that thought my curiosity leads me to wonder what the cylinder walls look like after having been washed down during the time the injector went TU until the truck died.



Another thought, and this comes from running #2 oil in gas turbine engines, is if for some reason that injector was getting no fuel it could have heated up until the point of breakage. I have seen this on Gas turbines but it is mainly because all of the combustion chambers are linked together and when one goes out the flame then propogates from the other into it and burns things up. Either way I think I would want to look inside, sounds like a good excuse to o-ring the head if not already done.

 

[Scot]

I will second Mundgyver. It looks to be highly crystalized. I would want to see a rockwell hardness test as compared to nominal values.

 

[RSnaith]

I don't believe the injector in the picture failed because of too many holes. If this were the case, the crack would have occured at the hole, and at least from the pictures, that does not appear to be the case. Its likely due to improper hardening of the tip. An excellent read on the EDM process and injector failures can be found here:



http://mysite.verizon.net/res06gkt/tipfailure.html

 

[dieselsam59]

i am not overly familier with the insides of the injectors in our trucks, but from the injectors that i have done it sorta looks like the damage came from inside the injector. Possibly the injector was set with to high of a pop-off pressure, hence tightening the spring - exerting more force on the nozzle every time the injector "pops" off slowly fatiqueing the component in question and pulling up a grade with rpms up and heat up well... ... . thats my thought

 

[pro99]

I was thinking the same with it being # 6 injector with heat, not allot of boost to that one in the back. Someone had a post about the temp being higher in the # 6. They put a temp in every runner of the exhaust manifold and it showed more heat than the rest.

 

[JR2]

Good stuff guys. The truck is running twin turbos and the EGT was at 1200 for a while. The injection pump also went south at the same time or so we think. It got a new injection pump before the injectors where looked at (basically because after the new pump the truck would not start). So it is possible that th injection pump when south, did not send fuel to #6 and it overheated and the tip broke.



Thanks and keep the ideas coming.



John

 

[ben_ak]

JR2, Where are you at??? I have a bore scope here in Anchorage. PM me if your in town.

 

[JR2]

Ben,

I will talk to the owner of the truck and see if they want to do it... I am leaving town in the AM.





John