2.4D (2005 on) Engine Knock

[Zafree]

Hi,

I am trying to figure out what is causing my xc70 d5 (D5244T20) to knock. The knocking / ticking is coming from the upper left side of the engine (cylinder 1) as shown in the video1 and video2, and it is more present when the engine is warm. Sometimes, when it is cold outside, the ticking can be barely noticeable.

I have visited four repair shops. All agreed that the noise is present, but no one could say for sure what was wrong with the engine. At the Volvo shop (last visit), I was told that the engine should be removed for a detailed inspection.

So far, the following has been replaced/performed.
- Hydraulic tappets
- Injector 1 and 3 ( refurbished by Bosch).
- All belts, tensioners and pulleys, water pump
- Engine compression test (warm):
Cyl. 1: 25.5 bar
Cyl. 2: 25 bar
Cyl. 3: 25 bar
Cyl. 4: 26 bar
Cyl. 5: 25,5 bar

According to VIDA, the injectors are within specifications. Leak off test is also within specs.

The engine pulls well, maybe a little sluggish at low rpm.

I also noticed the following:
If accelerate while driving and suddenly lower the RPM and then slightly press the accelerator pedal, the knocking may also disappear.

Any ideas?

[37 RUBY]

Hello

It is difficult to identify from the videos. My untrained ears can hear what I believe to be a noisy injector or tappet or pcv which is being amplified via other engine components.

Have either you or any of the garage techs utilised a mechanics stethoscope? It's my go to piece of equipment for tracing noises.

[Zafree]

Hi Ruby,

I would exclude hydraulic lifters as I have replaced them. I think I've played with the stethoscope for several hours now and I'm 99% sure the knocking is coming from injector 1 or cylinder 1. Listening without a stethoscope, I would say the knocking is coming somewhere behind the camshaft pulley.:/
Today I went to another garage and they think it might be a combustion related problem rather than mechanical (maybe the injector).
I have already spent 500 eur on remanufactured injectors with no succes.

I noticed oil leaking (not much) from the turbo. Could a defective turbo cause such problems?
The turbo itself does not make any strange noises.

[5cilinder]

I find it hard to hear the knock, but if its there it is caused by the mismatch in flow by the refurbishing and the coded flow in the ecu.

[Zafree]

The videos are not top quality, but please try to watch them on your phone. I am sure you will hear it clearly.

[5cilinder]

Well if there is knock its caused by the mismatch in flow by the refurbishing and the coded flow in the ecu, concerning injector 3 you were probably lucky.

Many people have problems with the refurbished injectors because of the expected flow by the ecu code.

[Zafree]

If I understand it correctly, the ECU controls the deviation and corrects the flow for each injector (fuel quantity correction). According to VIDA, the acceptable deviation is ±4.0 mg/cyc. In my case, these deviations are within ±0.5 mg/cyc. The replaced injectors were also within ±0.5 mg and knock was present. I swaped injetors nr.1 and 4, but knock is still there so i beleave it could be something else
Is it possible that the ECU is getting false readings from the injectors?
All injectors are coded.

[5cilinder]

I didnt mean the dynamic fuelcorrections i meant that the refurbished injector has a different flow than the STATIC coded value
The ecu assumes a certain flow and acts accordingly with the electric opening pulses of the injector if it assumes more flow with the corresponding number it wil open the injector electricly with a shorter pulse if those dont match you can get overfueling and advanced injection which causes knock

[Simmy]

could it be the vac pump these wear an become noisy.

[Zafree]

Yesterday I replaced the injector with a new one from Volvo, but the problem still persists.

If i unplug the connector from Injector 1 the knock completely disappear?!
I also noticed that injector 1 was a bit more sooty than the other injectors. :/