[pearj]

Hi,

I've got a weird problem with my 2009 SX 5 Door Wagon, Diesel 1.6lt, Auto, Silver where it randomly shutters/shudders.  The last time it happened I was going downhill at 80 km/h and it didn't need a gear change, the car semi-violently shuddered and I quickly looked at the RPMS and it dropped from just under 2k to about 1k. Then it quickly went back to normal.  It had done the same thing before the previous day, but not quite as violent and not going downhill.  But before then it was probably months since it had done it to me.  My wife drives the car mostly, but she says it is pretty random too.  Maybe once every few weeks.  It's been happening for 6-12 months I reckon, I haven't really been keeping track.

I just had the 105,000 km service at the dealer and I asked them about it, but they couldn't reproduce it.

I cannot reproduce it on demand either, it seems totally random.

These are my thoughts so far:

• Ruled out gear change problem because it happened going down hill
• Maybe some sort of fuel line problem?
• Could it be a timing belt/chain problem?  The next service at 120,000 is getting that done, maybe I need it earlier? How do timing problems present? Or are timing problems consistent failures?

What can I do?

[Dazzler]

  Early i30 manuals had a judder mainly in 3rd gear at fairly low revs (but not down hill)

I suspect a fuel quality or fuel system problem making the engine misfire randomly (but I'm no expert)

See what others say.

I'll summon the experts..

@cruiserfied @nzenigma

[cruiserfied]

Hard when it wont happen on demand.
First thing that jumps to mind is to check the in tank fuel strainers for Diesel bug.

[Dazzler]

Thanks Tim (sounds like I might be on the right track! )

[nzenigma]

Yes , like Tim, I constantly look to Daz for guidance. 
Same thought as Tim, ....fuel bug.
If so, there will be black deposits in the fuel tank and fuel strainer inside it.

The diesel motor has a timing chain. No need to change it.
Mechanical parts just break or rattle etc. Rarely are they an intermittent problem as you describe.

[Dazzler]

 

Thanks for the clarification guys.. So lucky to have your experience (and my guesswork) at our disposal... 

[pearj]

First thing that jumps to mind is to check the in tank fuel strainers for Diesel bug.

Thanks guys,

What is the Diesel bug? I have the car at the dealer replacing the seat belt socket this morning.  If I called up quickly they might be able to look in the fuel tank too, presuming it's not really complicated to do.  But would the tank need to be empty?

[pearj]

The diesel motor has a timing chain. No need to change it.

Are you suggesting that I wouldn't need the timing chain replaced at all next year? Ie the timing chain service is unnecessary?

[pearj]

What is the Diesel bug?

Oh, is it like an actual literal bug in the fuel tank? Diesel Bug Explained - Bacteria Contamination of Diesel - Freephone 0800 933 939 for more info

[nzenigma]

The diesel motor has a timing chain. No need to change it.

Are you suggesting that I wouldn't need the timing chain replaced at all next year? Ie the timing chain service is unnecessary?

Correct. No need to service or change it.
The bug is organic, at first it looks like opaque jelly. The black deposits clog filters. The tank entry is under the rear seat. Probably 15 min work to open up and take a look.
The fuel filter/water trap is on the firewall (engine compartment). It is easy and routine to drain it. The mechanic can check the drained sample for impurity. Put it in a clean glass, hold to light, do not drink, even at Xmas.

If you suspect your diesel fuel supply there are various additives that will defeat the bug's development. I use this, especially after a tank has been cleaned out. Liqui-Moly Diesel Algae Stop - Supercheap Auto
Good luck.

[pearj]

The diesel motor has a timing chain. No need to change it.

Are you suggesting that I wouldn't need the timing chain replaced at all next year? Ie the timing chain service is unnecessary?

Correct. No need to service or change it.

Interesting, why do they recommend as part of scheduled services to replace the timing chain then? Just a cash grab? Or is it because cars with timing belts need it so they just carried it over?  So the timing chain can't snap?

The bug is organic, at first it looks like opaque jelly. The black deposits clog filters. The tank entry is under the rear seat. Probably 15 min work to open up and take a look.
The fuel filter/water trap is on the firewall (engine compartment). It is easy and routine to drain it. The mechanic can check the drained sample for impurity. Put it in a clean glass, hold to light, do not drink, even at Xmas.

If you suspect your diesel fuel supply there are various additives that will defeat the bug's development. I use this, especially after a tank has been cleaned out. Liqui-Moly Diesel Algae Stop - Supercheap Auto
Good luck.

Can I use that stuff in my tank as a precaution without cleaning the tank first? Or does it only really help if the tank has been cleaned first?

I managed to get onto the dealer and asked them to look in the tank for bugs, so maybe they'll clean it out if they find something.  But if they don't clean it, can it hurt the car if I add the algae stop and it didn't need it?

[sundiz]

Interesting, why do they recommend as part of scheduled services to replace the timing chain then? Just a cash grab? Or is it because cars with timing belts need it so they just carried it over?  So the timing chain can't snap?

When timing chain is engineered well you don't need to replace it. Unfortunately it is a mechanical part and it may snap or strech. Some chains are just poorly manufactured. Never heard hyundai had issues with them. Few years ago mercedes had bad quality issues with some engines and you had to replace the chain after 90 000km. Often the timing chain tensioner is that part which causes problems. But in normal conditions timing chain do not need to be serviced. If some garage offers you change of the chain I would ask "why?".

Some engines have timing BELT, which is made of rubber. Those needs to be serviced at some interval...

[nzenigma]

On the petrol 2 litre motors the belt was originally scheduled for replacement at 90,000Km, later this became check condition at 90K and replace at about 130K.
If this coincides with your service book it maybe a misprint or yes a"cash grab".  As sundiz says, ask why? Not rational on a well made vehicle.
 Re the fuel conditioner;  a small amount can be used to prevent the contamination. If you get fuel from a garage with a big turnover you wont have a problem. I had an i30 this year that was dead because the owner bought diesel at a large BP station that was closing down. He got the dregs .
A double  dose of the conditioner will kill any existing contamination.
However, there will be muck in the bottom of the tank that is blocking the tank's pick-up strainer. If enough of it gets past the main fuel filter it can cause wear to the fuel pump and injectors.
 The stuff needs to be removed. I have done this by syphoning. No need to remove the tank from the car.

All this for one theory but at least it came from a great mind. Good one Daz 

[Dazzler]