1.6 CRDi Diesel Knock/Rattle

lrg · **September 07, 2018, 23:07:29**

Hi Guys,

I have a 2012 i30 CRDi with some knocking/rattling issues under very light acceleration. The problem started six months ago and has progressively gotten worse.

Here is a url of the noise it makes, the quality isnt very good. At the start of the audio if you turn it up loud you can hear the diesel engine purring perfectly as I apply a bit of throttle and then the knocking noise comes in. Its a bit distorted from the recording being taken from inside the car.

I have taken it to two different mechanics now. Both cant figure it out.

The first was the hyundai dealer, they said it was the fuel bug, flushed the system, charged us and fixed nothing.

The second mechanic has had a look and driven the car 4-5 times now.
-We have had all the injectors cleaned and tested.
-Changed the fuel filter
-Run two sets of system cleaners through. Apparently there was heaps of sludge/carbon buildup on the manifold.
-Cleaned the air and turbo flow sensors.
-Tested putting a ERG blanking plate in, but it changed nothing.

It seems to happen after the car has warmed up, and especially bad going up hills. Sometimes it comes with a loss of power, almost like a coughing/jerking/surging fit. You have to put your foot down on the accelerator to snap the car out of it.

Hopefully you guys have seen something like this before! Thanks in advance.

Voice 041 - Instaudio

Dazzler · **Reply #1: September 07, 2018, 23:20:33**

Welcome Irg.

Not being offensive but "Irg" was the noise I made when I read how much money you've already spent trying to fix this thing.

Very frustrating for you. I truly can't think of anything you haven't already tried but someone else on here is fairly likely to have some ideas. Pity you didn't find us sooner. Good luck with some helpful replies.

tw2005 · **Reply #2: September 08, 2018, 01:02:28**

Can't get link to work. The old fuel bug. You in SE QLD?

nzenigma · **Reply #3: September 08, 2018, 02:06:53**

would help if you could tell us Kms done and get the sound page to work, try a U tube vid.
I can understand the frustration, your mechanics are exploring two separate issues. The manifold/ ERG build up will have little to do with fuel bug. I expect the latter is resolved, system as clean as?

Have your guys tested or thought about fuel pressure.??
If your injectors are at the wrong pressure and especially if they are delivering excess fuel the engine will sound like a tractor.
Probably a bit hard to get at on your late model, but the pressure reg. on the fuel pump would be worth changing. Three torx screws hold it.

lrg · **Reply #4: September 08, 2018, 04:02:09**

Thanks for the replys!!
Yep, I am in SE QLD, apparently the bug is a big deal up here.

Shame about the link. Hopefully this one works.
Engine Sound Link

Vocaroo | Voice message

It looks like you can dload it as an mp3. If you can hear the audio file, it sounds very much like a tractor as you mentioned, in real life though it is a lot more tinny/rattly than the diesel pumps/tractors i grew up with. If it was just a beefy/rattly diesel sound id probably just forget about it, but the surging that comes with has me concerned.

I'll mention to the mechanic the fuel pressure info, hopefully he can have a look.

lrg · **Reply #5: September 08, 2018, 04:02:45**

Oh, and almost at 90k kms.

tw2005 · **Reply #6: September 08, 2018, 07:16:13**

Hearing of fuel bugs and Hyundai dealer reminded me so much of the Hyundai mob in Cleveland region that blamed that for my father's i30 randomly cutting out. Supposedly replaced everything and drained the tank twicr to not fix anything.

nzenigma · **Reply #7: September 08, 2018, 07:18:17**

Thanks for that. 90k is a low km motor, it should be still running ok into the mid 300ks.

That is the over fuel knock I was referring to, also surging would point toward fluctuating fuel supply or pressure.

I have had a couple of Bug dramas. Cant say SE QLd is problematic, from my experience, in climates where it drops to below zero they are really tuned into using fuel additive.
Get fuel from a station with a high turn over and you should be good to go.

Now we cant be sure about the dealer actually finding a bug or just finding your wallet.
I case there was a bug check the pressure sensor on the end of the rail. Could have gunk in it. But with evidence esp noise, I would change that pressure control valve on the pump.

Dropic Son · **Reply #8: September 09, 2018, 09:15:16**

What is the oil consumption?

The noise and the apparent time you say it gets worse suggest to me that the engine is suffering pre-ignition, which on a diesel can only happen if combustible product (oil) gets into the combustion chamber either past the piston rings, or via a leaking turbocharger seal, or possibly valve stem seals.

It would not take much oil to create the symptoms, but I would expect that you will see an increase in oil usage, as well as an unusual smell from the exhaust.

There would be a few other checks you could do to to help locate the culprit (if it is indeed an oil passing issue), or get your preferred mechanic to have a look. Unlikely you will find a dealer service department to have much capability in this type of problem.

Good luck!
DS

Dazzler · **Reply #9: September 09, 2018, 09:27:45**

Welcome DS,

An interesting and helpful 1st post. Do you have a mechanical background or are you just drawing on personal experience.

lrg · **Reply #10: September 09, 2018, 21:37:44**

Thanks for the replys guys!! Great info. and gives me something to move forward with.
Did my second attempt at posting a sound file work?

nzenigma
Ill check out the pressure sensor at the front end of the rail and see what's there, and have my mechanic price up a pressure control valve on the pump.

Dropic Son
There is quite a bit of oil going through the ERG, turbo etc, but it doesn't seem to be consuming oil. The exhaust smells pretty normal to me.

nzenigma · **Reply #11: September 09, 2018, 23:01:45**

You will normally see a small amount of oil coming from the turbo to the intercooler, this will increase a bit as the oil seals wear. The engine takes it up and burns it.
You blanked the EGR , the plate will have a small opening to bluff the ECU, but little oil can go that way now.

The distrust I have for dealers is a problem. Was there ever any bug? If there was a bug, did they completely clean the system?
It may be worth checking the fuel pick up sock in the tank. It could be clogged. It is a fairly easy task, lift the rear seat swab its a white plastic unit. It should have dealer finger prints on it

Uncilp the 2 lines and 8mm bolts and it will lift out. If you find black specks in the tank, you have had a bug, enough of it will clog the sock. Once had a vehicle that would shut down on a left turn because the stuff would slide over and block the inlet.

Dropic Son · **Reply #12: September 15, 2018, 00:53:32**

Many years in mechanical, both light and heavy automotive plus other mechanical oriented trades.

Dazzler · **Reply #13: September 15, 2018, 05:24:13**

Quote from: Dropic Son on September 15, 2018, 00:53:32

Many years in mechanical, both light and heavy automotive plus other mechanical oriented trades.

Cheers, a third or 4th opinion won't go astray.

lrg · **Reply #14: September 17, 2018, 03:23:56**

Thanks again for all the replys!

Im still not sure if you guys can access the sound file.

I opened up the fuel tank under the seat, clean as.. and you were right grease prints all over. As far as i can tell looking in there. There never was any issue with the bug. It is pristine.

Anway, I have been refered to a diesel only mechanic an hour away who only works on trucks/4x4s. He immediatly said it is pre-ignition, and it is only noticable at certain times because one of my valves is in a weakened state and probably not getting enough voltage at the time the rattle/knock happens.

Either way he seemed confident that it wasnt going to be a major problem to fix, so booked in to put it on the dyno and hopefully fix it in 2 weeks. Either pump pressure control valve or one of the other ones i cant remember the name of. Ill let you guys know the outcome.
Cheers.

Dazzler · **Reply #15: September 17, 2018, 03:43:48**

Quote from: lrg on September 17, 2018, 03:23:56

Thanks again for all the replys!

Im still not sure if you guys can access the sound file.

I opened up the fuel tank under the seat, clean as.. and you were right grease prints all over. As far as i can tell looking in there. There never was any issue with the bug. It is pristine.

Anway, I have been refered to a diesel only mechanic an hour away who only works on trucks/4x4s. He immediatly said it is pre-ignition, and it is only noticable at certain times because one of my valves is in a weakened state and probably not getting enough voltage at the time the rattle/knock happens.

Either way he seemed confident that it wasnt going to be a major problem to fix, so booked in to put it on the dyno and hopefully fix it in 2 weeks. Either pump pressure control valve or one of the other ones i cant remember the name of. Ill let you guys know the outcome.
Cheers.

Cheers, look forward to the update. Hopefully good news.

nzenigma · **Reply #16: September 17, 2018, 04:11:59**

Yes same from me.
Good luck, we await

lrg · **Reply #17: October 15, 2018, 21:04:20**

Hey Guys,

Heres an update. Had the dealer do a software upgrade and it has fixed or hidden 90% of the knocking. It is barely noticable now.. and only occasionally, so pretty good news.

tw2005 · **Reply #18: October 15, 2018, 21:13:02**

Quote from: lrg on October 15, 2018, 21:04:20

Hey Guys,

Heres an update. Had the dealer do a software upgrade and it has fixed or hidden 90% of the knocking. It is barely noticable now.. and only occasionally, so pretty good news.

HI

Can you expand on all of this please mainly because one of mine is rattly and has increased fuel consumption.

What was your economy like?

What happened to the diesel specialist and dyno, I was real keen to see what happened there?

How did you end up back at the dealer?

Was it the same dealer or another?

Did they mention how long this software update had been around or how common this issue was?

Did they write what version software package was loaded? maybe I could check what is loaded into to the wagon?

cheers

nzenigma · **Reply #19: October 15, 2018, 22:05:26**

More to this story.

Curious that you say 'hidden 90% of the knocking'. Is the other 10% abnormal or normal diesel sound?

Glad that you have it sort of sorted.

lrg · **Reply #20: October 16, 2018, 22:03:06**

I am not sure what software update they gave it, but it has been quite a while since it was last updated. Over a year at least. They have also indicated they adjusted the timing of one injector slightly.

To your question about the dyno, i got sick and couldnt make it to that particular mechanic as they are about an hour away and are booked out 2 weeks in advance. So I tried the dealer again.

No, it is not a normal diesel engine noise. I have been starting to think that possibly it is just the ECU mismanaging some information from some of the sensors in the car and sending wierd info to the injectors causing fuel to be sent a bit too early, but i am no expert.

Any any case, it happens pretty infrequently now.

nzenigma · **Reply #21: October 16, 2018, 23:17:29**

Quote from: lrg on October 16, 2018, 22:03:06

No, it is not a normal diesel engine noise. I have been starting to think that possibly it is just the ECU mismanaging some information from some of the sensors in the car and sending weird info to the injectors causing fuel to be sent a bit too early, but i am no expert.

or inversely, intermittent sensor sending wrong info to ECU.

tw2005 · **Reply #22: October 17, 2018, 08:54:11**

Quote from: nzenigma on October 16, 2018, 23:17:29

Quote from: lrg on October 16, 2018, 22:03:06

No, it is not a normal diesel engine noise. I have been starting to think that possibly it is just the ECU mismanaging some information from some of the sensors in the car and sending weird info to the injectors causing fuel to be sent a bit too early, but i am no expert.

or inversely, intermittent sensor sending wrong info to ECU.

Or adversely inadvertently inadversely universally NFI