I have 2005 2,8 JTD engine in my motorhome. Engine is 128 ps and without EGR. I have noticed weird noise from my engine, when driving in low load about at 2000-2500 rpm. I would describe this sound as knocking or ping. Almost like too big valve clearance. You are able to hear it especially when engine is warm. With cold engine not so much. As far as I understand the noise is related to fuel injection, because when it appears, you can control it with throttle pedal. I would call this noise as rattling.

I heard this same noise on last autumn, but not so loud. Noise keeps increasing and appears every time with same rpm area. Filters are new, there are no leaks, no fault codes, no warning lights etc. Our local diesel service checked parameters with tester (during test run) and no exceptions. They also tested all nozzles and no problems. Next they will try new fuel pressure indicator (or switch), which is in the rail.

Good ideas, anyone? I'm frustrated, because we are going to start our summer holiday journey after two weeks.

Hi. What do you mean by supermarket fuel? In Finland we only have one kind of diesel. Ok, I had half tank of "arctic" diesel in during the winter. I think that this the second full thank after winter and diesel quality is different now in the spring time.

Hi.
Didn’t realise where you are, in the U.K we can buy cheap diesel at supermarkets most cars run o.k on it, but some don’t.
I have had two JTD’s and they both run bad on this type of fuel.

Ok. Probably this is something else, but I don't know what. I was full of hope when I took my car to service, because nozzle failure seemed obvious to me. As we know by now, it is not the reason.

Please give me more ideas to solve this roblem.

Did you use easy start or anythingto get is started during the winter? If so could be rod knock.

I don't use my car in the winter and if I start it, I don't need any easy start or start pilot. Like I said, I had this same rattling in autumn, but it was not this loud. For me, this sounds like water in the fuel or something like that. Rod knock would probably give much louder noise and over total rev area.

Hi I had knocking like this on my diesel brava, local mechanic could not find problem. searched this forum, found out to be the flywheel had rubber centre that had perished.

Re: Ducato 2.8 JTD engine "knocking" SOLVED

I just picked my MH up from local service and the noise is vanished. The reason was fuel pressure indicator. Pressure in the rail was bigger than it should have been, although pressure value seemed to be ok. Now 90% of the noise is gone and the rest 10% is part of the common rail technique and comes with a car.

Thanks for everyone, who helped me with this problem.

Re: Ducato 2.8 JTD engine "knocking" SOLVED

Glad it was a realtively cheap fix, seen two of the sensors go bad but both were intermittant. I would have though that if the pressure was high it would be knocking all the way up the rev range but I suppose as the revs increase the injectors are open more often and relieve the pressure in the rail.

Re: Ducato 2.8 JTD engine "knocking" SOLVED

No no no! I have driven about 100 km since they changed new pressure sensor in the service. I think that sound or noise is getting louder and louder again. Why??

Like I described earlier the sound is same as you can hear everytime, if you listen very carefully your engine in low load (about 2000-2500 rpm) and you gently push more gas. Now this typical sound gets louder and louder and at the same time sound is more and more rough.

Re: Ducato 2.8 JTD engine "knocking" SOLVED

I have a similar noise at these revs and I discovered that it is the silencer in exhaust system resonating.

I too have exactly the same issue! Could it really be the silencer causing such behavior?

I don't know about your case, but mine is / was certainly not the silencer. I'm not a professional, but I'm still quite experienced at least what comes to petrol engines and I'm sure that this is not a voice from silencer.

Anyway, I just returned from our holiday trip and I just drove about 5000 km without problems. I still can hear the voice, but it is not as loud as it was. That's why I keep on going, if the voice doesn't get louder.

OK, so do you mean that the sound is still 90% less when compared to when it was as worst? Or did it return to some degree from being 90% lower, while still being much less than when being worst?

Did you have to change a sensor/indicator or some kind of pressure regulating unit? Was it expensive? Asking a lot, but I too am about to go on summer vacation and you know the stress it means when there is troubles like this...

Can add to that that the MH is bought in Finland(Kempele,Oulu) in the end of April. They said there is some kind of warranty for 3 months after buying, maybe this is a case when the seller(a company) should fix it? (You live in Finland so maybe you know about the used car's warranty companies use there, hehe?)

If you have 3 months warranty and this time is still not finished, you certainly should contact the seller. Warranty should include this kind of problems. It doesn't include wearing parts, but this is not that kind of component or problem. If they ignore you, you can always contact "Kuluttaja-asiamies". I don't know how to translate it in English or Swedish, but they are here to fight for our rights against mean sales men. If you need any advise, you can contact me directly.

They changed pressure sensor to my car. It's in the middle of the fuel rail. It cost about 230 eur. I think that the sound I have is bit more than 10% of the original, but I might be imagining. Maybe it hasn't increased and I have just got used to it.

It's always big stress, when long trip gets closer. I hope you can get you problem solved and you have a pleasant journey.

Thank you for your kind help! I will contact the seller and tell them about this problem, as well as another problem regarding the fuel indicator not showing reasonable values. (Either shows too little or jumps around)

The workshop company the MH selling company uses for reparation and service said they hadn't heard of such thing like a bad fuel pressure indicator. They were concerned there is going to be severe damage if I continue to drive, making the MH selling company not willing to pay for that. I think they are exaggerating a bit, hehe. The noise doesn't sound that alarming, just annoying.

Went for a short test drive this evening, I noticed that driving almost exactly 40 km/h or more on 2nd gear makes the noise disappear, same goes for 3rd and 4th gears at 60 and 80 km/h and more.

Janisto76: Could that be the 2500 rpm you mentioned?

Question is if the mechanic did understand my friends explanation. hehe. Engine technical Swedish to Finnish translation can be a bit hard, haha!

Janisto76: Did you get the impression that the faulty pressure indicator is an uncommon problem?

Now I have got confusing information about the possible cause for the "knocking" sound... On our way down to Pietarsaari/Jakobstad in Finland we stopped by in Oulu and had a mechanic listen to it. He said it is caused by too low fuel pressure due to the fuel getting too hot when the engine is warm. He said that the early MCU programs in the JTD engines uses too few "levels" when regulating the fuel pressure and so when it gets warm the fuel pressure gets a bit too low. He thought that it might disappear if a MCU program update is done. It was however not possible to neither do that then, nor to check the fuel pressure, but as he said that it isn't a severe error causing some kind of break-down that was not a big problem.

More of a problem is the fact that too low pressure is the opposite to Janisto76's cause of problem. Hmm... Feels like the fuel pressure should be measured after all...

Yesterday I drove 400 km and now it seems that the knocking is heard more frequently and maybe also louder. I heard it also at higher speeds on 2nd,3rd and 4th gears, which I did not do before. Even on 5th gear it was heard more generally. Doesn't feel too good...