[kikuma25]

Originally Posted by SS-Traveller

To summarize, the noise that members have been experiencing can most likely be from one of 3 sources:
- Valve-train noise due to reduced hydraulic damping caused by non-standard oil filter/higher viscosity oil (an oil + filter change should sort it out).
- Combustion clatter due to a cleaned-out combustion chamber, thanks to Shell detergents (that's a good thing).
- Ignition / combustion knocking, due to failing / failed knock sensors (more likely in a spark-ignition engine, less likely in a compression-ignition engine).

Thanks gentlemen for these observations. Better late than never!

I changed the oil + filter and the clatter continues. Anyway, Hyudai claims it never used any aftermarket filter other than original Hyundai ones.

Cleaned-out combustion chamber should result in higher engine performance, I think? In my case, there is visible loss of torque; also fuel efficiency has dropped from 14km/liter to 11.5km/liter of diesel. So, this also seems unlikely to be the cause of the clatter.

But, this leads me to a different thought. Assuming premium shell fuel displaced any carbon deposits, should I try an engine flush now?

Tucson has a compression-ignition engine. Anyway, I will talk to the Hyundai mechanic about knock-sensors and see what comes of it. I suspect he will give me a blank look - most of them are pretty illiterate when it come to real mechanic work. Mosttimes, it is like talking to a brick wall.

I got another tip that this could be due to clogging of CVVT (continous variable valve timing device) due to low viscosity oil usage. Does the Tucson CRDi have a CVVT at all?

[SS-Traveller]

Originally Posted by kikuma25

Does the Tucson CRDi have a CVVT at all?

No - Tucson's engine does not come with variable valve timing.

Why don't you shift back to normal (regular) IOC /HP etc. diesel and see if the clatter goes away after a tankful / and/or mileage improves after a tankful. Hyundai recommends normal diesel anyway - so does Toyota.

[manjubp]

Originally Posted by krisna

Yes. Even my car started giving the knocking noise with Shell petrol.

Yes, even my car started having knocking noise with shell normal petrol, from last 4 fills. However when I changed to BP, no issues. The MASS guys during service informed that they have adjusted to Timing to take care of knocking, but it still remins with shell petrol.

regards,
-manju

[AppyS]

New i20 Cvt giving same knocking noise, 2 road tests later the floor engineer just asks, "You use shell only dont you?" Couple customers on hyundai have had same issue with Shell they say.
Giving it for fuel tank drain and clean, with oil filter cleaning as well. I guess i felt same with my polo too in Shell. Guess its time to say bye bye to Shell.