How do you tell when your injectors are on the way out?

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glennm

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Have noticed a few posts lately about injectors being replaced or planned to be replaced. I have a ticking noise that has been suggested might be the injectors. 155k on the engine. Ute runs fine and no/minimal smoke. Timing chain and fan belts have been done. Sounds almost like an exhaust leak but can't find any evidence of one. Not there at idle or below boost.
 
Injectors will sound like a rattle can under the hood. Will usually be quiet at idle and WOT but loudest under moderate load and especially when you back off from load ie at the top of a hill. Usuallu between 1200 and 2500 rpm. Diesel knock. Vibration under load, perhaps smoke. It all depends on how they are failing.
 
Thanks iceman. Is there a park oint at which they should be replaced? Do they cause any damage as they get worse? First diesel in case you hadn't already guessed.
 
Hmmm hard to know really. Guess its how long you can put up with the noise. An injector that is out of spec due to wear etc can over fuel on one or more cylinders and potentialy cause damage to piston etc. it over heats the crown which can crack or melt and blow a hole in it. Obviously not good. Diesel knock is premature ignition of the fuel just like pinging in a petrol and does similar damage. Its all about air fuel ratio and atomisation and a bunch of other things i dont really understand! I would first try at least a liquid moly purge, maybe two and a ecu reset. Could just be the injectors need a real good clean. If they get some crud in them they can dribble rather than spray with a similar effect. Our common rail setup is super duper sensitive to any foreign matter at all. Remember the ecu is programmed to inject a certain amount of fuel depending on demand, air available and so on. The amount that actually goes in to the cylinder is down to how accurate the injector has stayed since it was made or at least last measured. In reality the expected injection quantity and the real quantity are potentially quite different which stuffs up the ratio.
At only 155k i wouldnt jump to the conclusion that it is an injector. They seem to be able to do around 180 to 200k in alot of cases. Having said that mine are totally shot at 178k! And i have heard of them going as low as 100k. Luck of the draw or fuel quality or manufacturing tolerance or driver behaviour, who knows! I do know any water in the fuel will quickly damage injectors. Water at these pressures is an incredible cutting tool.
Over all if its a ticking i wouldnt worry about it. If its a loud and embarrassing rattle it could be injectors
 
Thanks again iceman i was reading about the diesel purge so will get the gear together for that and see how it goes. I have had dual filters on it since near new as i was aware how bad water can be. Will post back how i go.
 
Completed the purge yesterday and the injectors seem quieter. Might redo whe i do the oil at 160k.
Thanks again for the help.
 
Hi Glen, normally when the injectors fail they tend to weep. That is not fire correctly, yours should be ok with those low kms, perhaps the purge cleaned out any muck?.
John
 
I get injector rattle on a cold start up which lasts untill the engine is up to operation temp. You can still slightly hear it when the engine is warm, but only if you listen for it. Under low throttle it is worst, but under heavy throttle it goes away. Is that normal, or a symptom of injector fail?
 
It's probably better described as "rail chatter", the 450 Nav runs a slightly higher pressure than the early model and can appear louder. Nothing to worry about.
 
Last edited:
Hi Glen, normally when the injectors fail they tend to weep. That is not fire correctly, yours should be ok with those low kms, perhaps the purge cleaned out any muck?.
John

Thanks hj i am hoping that is the case. Now that i have done it once i am not so concerned about doing it again. All sounds daunting when you first think about it but thanks to rusty's sticky it all went off without a hitch.
 
Second that, it's called responsive by responsive engineering
It's a lubricant and helps control bacteria in the tank.

10ml every three tanks and mine seems to run a lot quieter
 
Good to hear Glen, I use the injector cleaner that you add to the tank often. How's that battery setup going mate?.
Brilliantly thanks hj. Sits there quietly doing its job and completely out of the way. Gotta be good for its longevity too being in air conditioned comfort.
Ps nice to have you back!
 
Thanks Glen, I am about to install my invertor behind the seat, it powers the three way fridge in the van when we travel and a 20 amp charger for the van's house batteries. Along with the 160lpm compressor I am running out of space.
Regards
John
 

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