i have a 2002 c15 6nz and 9 months after replacing cylinder head and replaced all injectors with cat remans. have been losing injectors especially #6 have had it replaced 5 times over 275000 miles first 500000 never had a problem. cat wants to pull the head to determine if it could have been a head not machined correctly , all this on my dime .i said no cause if the head comes off i will probably do a rebuild as engine has 778000 miles and over 27000 hours and hauls gravel local always grossing over 100000 lbs. oil samples all come back fine do you have any idea what the problem could be,work has been done by certified cat tech who is the owner of the cat shop very reputable,he says cat has many bad injectors out there,at one point replaced all injectors with brand new cat injectors, cat warranty rep wanted the head to come off
Engine: c 15 6nz 63322
Hi. Thanks for using JA! I will try and help you out.
I must say I have not ever seen an engine lose an injector 5 times. That is very odd.
When the injector failed, did the engine have a dead miss on #6 cylinder?
no dead miss, it would start as a hard start(losing it prime) and then gradually no smoke but obnoxius fumes and then would start smoking a week later , sorry upon starting engine a plume of smoke(fuel) but after intial start and plume of smoke it would run clean ,seems to run better when cold. i hand prime it to get started as it turns over toomuch
Thanks for the information.
If the engine is loosing it's prime, I would suspect the fuel is leaking down out of the engine. The main thing that causes this is a faulty fuel pressure regulator, I have seen this before. The regulator is located underneath the secondary fuel filter housing. I have replaced many of these for this problem. If the regulator is OK, the fuel transfer pump can cause the fuel to leak down out of the engine.
Please let me know if you need more help.
yes i realize that but when a cut out test is done and there is smoke coming out of the stacks and cylinder 6 is cut out it stops smoking ,if it was fuel regulator it would continue to smoke wouldnt it also once the cut out test is done and it was determined it appeared to be #6 we would swap #6 injector with #5 injector and the smoke would follow the #6 injector. if it was the transfer pump it would be the same results, the old transfer pumps had a weaker spring but they corrected that on this engine
I see. Thanks for the information.
From what you are telling me, you are correct. It is definitely an injector problem. If you cut out the cylinder and the smoke went away, it is definitely the problem.
I have had problems like this with reman injectors. I can't say I have had this many on one engine, but I have had a few on an engine. To be honest, I would want to try a new injector first before the head. I can not see how a head can cause an injector to fail like this. I would suspect reman injectors as the problem.
Let me know if you need more help or have more questions.
i have been going thru this for 3 years and have put all new injectors in at one point as suggested by my cat tech and took out a 4 year warranty on the injectors (for $300) and the #6 went bad and cat replaced it with a reman' that is there warranty , and then that injector failed and a that point the cat rep said that the head had to come off to rule out whether it was the head,everyone i talk to says the same as you ,they dont know how it could be the head,anyway i am at this crossroad again and i really dont want to do a rebuild yet as this engine is still running fine and strong, but if the head comes off i feel i might as well do the rebuild since the engine has that many miles and hours on it or if it was your engine would you just replace the head and injectors?
The only way I could think the head was the problem is if there was some sort of casting problem that caused a cooling problem around the #6 injector. I can't say I have seen this before but if you have tried new and reman injectors and still have this problem, I would have to say I would want to try a head. If the engine is running good, I would just try a head and injectors.
at 500000 miles when the head and injectors were replaced everything was fine then at 552000 and 7 months later the problems started they have continued every 4 to 7 months for 3.5 years and it is very aggravating and expensive, so all the problems after the original head was replaced, is there any way the ecm could cause a failure in a particular cylinder
Thanks for the information.It is possible that the ecm could be responsible for the short life of the injector. I have only seen this one time about seven years ago. We took the ecm off another engine that had thrown a rod and put it on the engine that had several injector failures. The engine did not lose another injector after swapping the ecm .
23 Years Caterpillar Engine experience.
just to fill you in ,found the problem, in the seat for the injector(after taking out the injector sleeve(cup) there are three cracks in the head letting combustion come thru and eventually melting the o ring on the injector
how hot does temperature get around those o rings on the injectors, was thinking of trying a ultra high temp o ring rated to 600degrees f. do you think this could work for a hold over until summers end and then finally addresss the head problem. also can the head be removed , cracks welded and then remachined (the injector seat)
Thanks for the update.
I am glad you found the problem.
Actually, there is enough coolant around the injector to keep it cool. The temp should remain around the operating temp of the engine.
I am not sure if the head can be repaired. I would contact a machine shop and have them take a look at it.