1.2 tsi sounds like conrod knocking, but workshop inspected they were fine ? Pls. listen

[mikkelvitus]

Hi,

I will try to do this short, most of all i would like you to listen to the video. The knocking sound is periodic, but comes mostly when the engine is hot. The belt is off, sp its not from the compressor, generator aso. Car is octavia 1.2 tsi 2010, with new chain ffitted 70.000 km ago. It rattles 1-2 seconds at startup and then no more rattle. This knocking also sounds more like metal to metal.

 

At about second 10 you hear 1 knock, then there is a little break, and then the knocking is present. As far i can figure, the knocking has a frequency about 1/4 of engine rpm. The engine idles at 720 rpm, and there is about 3 knocks per second. A skoda mechanic has heard the video, and he was sure it was conrod bearings, the present engine workshop could not get the engine to knock, but also heard the video and said conrod bearings, but now the car sits at the engine workshop without oilpan, and they have inspected all conrod bearings, and according to them, they are as new ? The have done a conference with audi in flensburg, and they say that the knocking sound also could be the chain - i just dont understand if the chain makes such perfect knocking sound following the rpms of the engine. Its DAK DAK DAK DAK very consistently when its present. Because it is possible that the knocking dissapears.

I would be very glad, if you could try to hear the video. After i hold the phone out the window approx. at second 10 there comes 1-2 loud knocks, then a little pause and then 2-3 seconds of knocking at idle speed. I then give a little gas, and the knocking frequency raises. When i run out in front of the car the knocking has dissapeared and the engine sounds normal. Remember the aux belt is dismounted, so the compressor, generator and water pump does not turn.

 

Is it possible that a trained specialized engine workshop can misdiagnose conrod bearings ? Do you believe its the chain making these regular metal knocking sounds ?

BR
Mikkel

[Guest]

After listening with headphones, could it be dual mass flywheel instead?

[mikkelvitus]

4 minutes ago, MicMac said:

After listening with headphones, could it be dual mass flywheel instead?

Its an 1.2 tsi, and its a single mass flywheel.

But the gearbox was demounted and a new clutch fitted, 3 months ago. Can there be loose bolts or something ?

[Guest]

1 minute ago, mikkelvitus said:

Its an 1.2 tsi, and its a single mass flywheel.

But the gearbox was demounted and a new clutch fitted, 3 months ago. Can there be loose bolts or something ?

Ask the mechanic who carried out the work!

[mikkelvitus]

5 minutes ago, MicMac said:

Ask the mechanic who carried out the work!

Yes i have just emailed him, but i dont think i comes from the clutch. Its very periodic. the car managed to idle for 15 minutes before there was some knocking.

Other suggestions are welcome

[Guest]

If it was running and knocking it should be easy enough for an experienced mechanic to locate the source using a stethoscope type device or a very long screwdriver.

[mikkelvitus]

3 hours ago, MicMac said:

If it was running and knocking it should be easy enough for an experienced mechanic to locate the source using a stethoscope type device or a very long screwdriver.

I agree. The car was transported to the workshop by a transport company, and i had over the phone beforehand talked to the boss. I got a phonecall from a mechanic, telling me, that they had listen to the car with a stetoscope for 20 minutes, trying to find a knock, but the knocking was not present. There was no mis-soounding of the angine at all. Then i mailed the video, and the mechanic immeadiately said, that the knocking on the video was not present, but no doubt that was conrod bearings. They dismantled the bottom of the engine, and told me, that by inspection and measurements the conrod bearings was not at all defect. and because the engine is now dismantled it is not possible to run it for further investigation 😕

The oil chain was very loose, and he said that they had found some plastic pieces in the oil sump.

[TheClient]

Could it not be timing chain tensioner and guide problem then. They seem to be saying as much. 

 

Are they replacing those? Is the car still disassembled? 

[TheClient]

There Is usually an inspection plug to view the chain tensioner. There is on ea888 engines anywsy. Have they viewed the tensioner? If it's fully extended the chain has stretched and the tensioner will eventually be unable to cope. I am unsure of the exact tensioner design on 1.2 two  but if it is hydraulic it probably similar to the ratchet hydraulic system that had a lot of problems in the past.. 

Edited 13 August, 2020 by TheClient