[geminiman]

When accelerating from cold the engine sounds smooth and refined, but when it warms up it I can hear a diesel-type knocking noise up to about 2300 revs, especially in first and second gears. I've taken it to my local Hyundai dealer twice, but on both occasions the noise wasn't there. On one occasion I parked on my drive, switched of the engine and came back 5 minutes later. The knocking noise had mysteriously stopped when I was accelerating. It does seem to be intermittent.  The car is 20 months old (I bought it 2 months ago) and has done 14,000 miles. Any ideas folks?

Your help would be greatly appreciated as this is spoiling my enjoyment of an otherwise fine car.

[Phil №❶]

What type of acceleration are we talking about, throttle just open and gentle or sporty wider opening throttle

[geminiman]

Hi Phil,when using anything from moderate to sporty acceleration the noise is most noticeable. On really gentle acceleration it sounds ok, only seems to be when I load the engine. It's not obvious from third gear upwards at any revs or throttle setting. Thanks for your reply.

[Dazzler]

It's a hard one to give an opinion on. I don't suppose you could record it on your mobile phone for us to hear next time it occurs. Might be hard to pick up from that though. One of the problems is people have different sensitivities.  What sounds loud or worrying to one may be classed as insignificant to another. Now you are aware of it I can understand it playing on your mind.

I'd just send an email to the dealer and to Hyundai saying you have this intermittent knocking noise which you have reported to the dealer twice and you wanted it noted in your cars records for future reference.  Make sure you get all services done by the book and stamped by a dealer or independent professional.  You have plenty of warranty left.

If it gets worse or you notice a drop in performance go straight back to the dealer.

[Phil №❶]

Diesel engines when under little load and not moving much air make a different noise than when working or cruising. It's a little like the knocking sound found in petrol engines using the wrong octane fuel, however in this circumstance, is perfectly normal. The sound is caused by the complete ignition of the Diesel fuel mixture due to engine compression.

[nzenigma]

Much of the normal diesel noise will be accentuated by the action of the injectors. The new high pressure Bosch injectors are quite refined. So various driving periods/conditions may result in a more audible diesel noise.

[diesel1984]

There are various types of noises..
If you can upload video or sound of this noise someone will clearly say if it is normal or not.

[geminiman]

Hi nzenigma, thanks for your reply. I don't understand why the noise is intermittent, although becoming more frequent, and why it is so refined when cold. Is this normal for this engine?

[geminiman]

Hi Dazzler, I have taken it to the dealer twice and they have recorded both visits. I get frustrated because the dealer sticks it on the diagnostic machine, which shows no errors, but don't do anything else.

Is it possible that the ECU mapping has been corrupted and is causing the problem, or one of the injectors is slighly loose or misaligned. In a former life , I was a computer programmer so I am aware that software is NOT always perfect when diagnosing problems. It wasn't like this when I collected it 2 months ago, only started about 3 weeks ago. Thanks for helping.

[geminiman]

Thanks for the response, guys. I will try to record the knocking when it occurs, which might be problematic due to tyre noise, but I'll give it go. Thanks for the advice, will get back to you soon.

[geminiman]

I have tried to record the engine noise using my phone, but it just sounds muffled and not loud enough to pick up the knock. The best way I can describe the noise is: on tickover all diesel engines exhibit that typical diesel knock, well that's what my engine sounds like when revving all the way up to about 2500 rpm, and gets worse the hotter the engine becomes. Hope that helps you guys to offer me some advice. Thanks again.

[Dazzler]

To be honest, you probably should just turn up the stereo and enjoy the car. You have plenty of warranty.

You could be on a hiding to nowhere. I doubt it is a ECU/BCM issue, although I agree software can get corrupted

I wonder if we have any active members nearby (with the diesel) that can take a listen?

[AlanHo]

The UK is a big place - we would need the OP's location

[Dazzler]

The UK is a big place - we would need the OP's location

True! @geminiman

[diesel1984]

Only thing that should be activated at 2500rpm is inlet manifold swirl flaps.  Sound may be different if they are partialy blocked or opened all the time.

[geminiman]

Thanks to you all for your replies. Good idea Dazzler  . With that in mind, if there are any active members near Telford in Shropshire I would be happy to meet up.

Diesel1984, is there any way I can check if the swirl flap is opening incorrectly. Would that show on the diagnostic testing at the dealers. Thanks.

[diesel1984]

You can check swirl flaps with any better diagnostic (not with elm 327  ) that have ability to activate bidirectional controls.

As actuator is not vacuum operated you can check it only via OBD2. This actuator is maybe out of range and it only needs calibration.

c/p from manual
FUNCTION AND OPERATION PRINCIPLE
Variable Swirl Control Actuator consists of DC motor and position sensor which detects the position of the swirl valve.
At idle or below 2,500rpm, the swirl valve is closed. This swirl effect increases air flow rate.


 
 

[nzenigma]

Little mentioned as a problem, but here is an old thread on the topic.
Swirl motor

[geminiman]

Thanks for that nzenigma, I've had a look at the link you kindly enclosed. I shouldn't think that is the problem as I have no warning lights showing, which 'Smiler' reported on his post. Back to the drawing board, I guess!!

[geminiman]

Thanks Diesel1984, great explanation of how the swirl valve works. From the link the nzenigma sent me, it seems that a warning light would come on if that was the problem. Thanks for the explanation, though, I'm learning a lot about my car from you guys.

[alex2jz]

I have the same issues on my Ceed 1.6 CRDi 136. Engine was sounding perfectly in the first 200kms (it was so quiet and refined that i almost thought i got a petrol instead of the diesel), then it started developing an intermittent knock/tapping. No lights, no other symptoms during driving. Only thing is that the exhaust is quite smelly on the cold starts, once at operating temperature it smells normal. Went to the dealer twice, said everything is normal. Also, can't quite get it on video either. Now at almost 7 months of ownership, i learned to live with it. My other car, Peugeot 1.6 BlueHDi 120, doesn't make these kind of noises, nor does the exhaust smell on start-up. 

[nzenigma]

Mate, almost all excessive diesel noise is caused by over-fuelling. There are a number of reasons for this, we have given  you something to consider. Stay in touch.

[tw2005]

Not sure if this has been quoted but interesting to read. 1.6 CRDi Diesel Engine Noisy & Knocking Like A Petrol Engine Pinking ?!

Have some interest myself  in the topic. having 2 i30s, one a CW. Chalk and cheese both in fuel economy and noise at low RPM , light loads.

[nzenigma]

tw and I have been having this discussion for a while.
In his case his noisy i30 is also the most fuel hungry.
It also has a new motor, so the original ECU may not have been updated.
again it sounds like over fuelling, but the cost of verifying the problem may be more than just turning the radio volume up.

[tw2005]

tw and I have been having this discussion for a while.
In his case his noisy i30 is also the most fuel hungry.
It also has a new motor, so the original ECU may not have been updated.
again it sounds like over fuelling, but the cost of verifying the problem may be more than just turning the radio volume up.

thank god for a good sound system. Thought I'd have a look at the ECU swap, mission impossible getting to the immobo unit, very disappointed.

[alex2jz]

This is how the area next to the first fuel injector looks like on mine. Is it normal ? The car only has 5800 km.

Imgur: The most awesome images on the Internet

[tw2005]

This is how the area next to the first fuel injector looks like on mine. Is it normal ? The car only has 5800 km.

Imgur: The most awesome images on the Internet

I hate guessing but I'm thinking not. You have 3 other injectors to compare to. Looking at the colour I'm thinking the injector is not sealing at the head, even that fuel line joint looks moist and black. Gases escaping?

Just another thought, if the rocker cover is black, because I was thinking it looks oily black around that injector, leaky fuel line a possibility?

I'm sure when you take it back under warranty you'll  find out.

[alex2jz]

This is how the area next to the first fuel injector looks like on mine. Is it normal ? The car only has 5800 km.

Imgur: The most awesome images on the Internet

I hate guessing but I'm thinking not. You have 3 other injectors to compare to. Looking at the colour I'm thinking the injector is not sealing at the head, even that fuel line joint looks moist and black. Gases escaping?

Just another thought, if the rocker cover is black, because I was thinking it looks oily black around that injector, leaky fuel line a possibility?

I'm sure when you take it back under warranty you'll  find out.

Thank you for the insight ! I've started the engine with the negine cover off and there are no obvious signs of gases escaping in the injector area. Also, there is absolutely no smell of fuel in the engine compartment at all. I'll check more closely the other injectors, but this definitely stands out. Also i will check the other diesel i have from Peugeot and see how the area around injectors looks like. I've showed the photo to the dealer as well and they said to come for a check as they can't identify from the photo if it's fuel or oil.

Alex

[tw2005]

This is how the area next to the first fuel injector looks like on mine. Is it normal ? The car only has 5800 km.

Imgur: The most awesome images on the Internet

I hate guessing but I'm thinking not. You have 3 other injectors to compare to. Looking at the colour I'm thinking the injector is not sealing at the head, even that fuel line joint looks moist and black. Gases escaping?

Just another thought, if the rocker cover is black, because I was thinking it looks oily black around that injector, leaky fuel line a possibility?

I'm sure when you take it back under warranty you'll  find out.

Thank you for the insight ! I've started the engine with the negine cover off and there are no obvious signs of gases escaping in the injector area. Also, there is absolutely no smell of fuel in the engine compartment at all. I'll check more closely the other injectors, but this definitely stands out. Also i will check the other diesel i have from Peugeot and see how the area around injectors looks like. I've showed the photo to the dealer as well and they said to come for a check as they can't identify from the photo if it's fuel or oil.

Alex

best option, it is next to the filler so could be spilt oil?

[nzenigma]

Not sure if this has been quoted but interesting to read. 1.6 CRDi Diesel Engine Noisy & Knocking Like A Petrol Engine Pinking ?!

Have some interest myself  in the topic. having 2 i30s, one a CW. Chalk and cheese both in fuel economy and noise at low RPM , light loads.

Gerard, in the topic you refer to suggestions of fuel quality were raised but did not apply in that case; but some other members claimed to have improvement after the ECU was updated/flashed.
The problem was eventually solved:

"It's fixed! I had it in to the local Hyundai dealer on Tuesday and they test drove the car and confirmed the knocking / noise. They looked the issue up on the Hyundai database of known faults and found a technical service bulletin covering this exact problem! They replaced the injectors and now the car is back to its old smooth & quiet self! "
[/i]
The author later made it clear that probably only faulty injector(s) were replaced.