VW Passat 2013 - CAYC 1.6 TDI - noisy and rough idle when warm.

Hi, Sorry if i have posted in the wrong place as its a while since i have been here.
My friend has had the misfortune of his cambelt snapping after his water pump failed and literally broke the belt and split the cambelt in half, the sad thing is documentation states it was replaced 10,000 by the garage it was purchased from by the 2nd previous owner.
Anyway the head cam cage was removed 4 new rockers replaced 4 new tappets that were weak. placed back together and it wouldn't start. Then we diagnosed 3 injectors (ignition off during removal and assembly) open circuit and 1 shorting to earth. 4 were purchased referred and coded to the car with VCD's engine immediately stared and ticked over like a swiss watch.
Then when warm it was noisy and started missing getting noisier and worse as it warmed up. 1 hr. later started the engine and the same sweet when cold and noisier and lumpy when hot. so of with the head all new tappets rechecked followers reground the valves and did valve leak test. Reassembled paying attention to timing marks and twin cam for alignment. We have ran diags using ODIS and VCD's and even OBDeleven. Other than some faults for disconnecting items that were cleared it shows no faults. The engine can be seen running here on Y'tube here when cold VW Passat 1.6TDI (CAYC) at temperature erratic part 2 - YouTube and when warm VW Passat 1.6TDI (CAYC) warming up all fine part 1 - YouTube.

We have ran all the output tests, Live data and all looks well until warm then live data seems to fluctuate except rail pressure injectors readings are up and down as are the other readings, even reset basic settings on throttle body and EGR still the same when cold it starts and runs well as well as before the belt snapped. when warm it misses on initial start and lumpy revs poorly, if it was a petrol i would say cranks sensor or something like that. But nothing has changed other than what you see here.

Any ideas and help greatly appreciated.

I suspect it hit which could have bent a rod, I won’t rebuild those when they hit, all I will do is fit a full exchange VW engine.

Hi Crasher,
Thanks for your reply.
Its plausible but pistons had no marks at all, oil pressure fine a rod even little end would reduce to a flicker of the oil pressure light when warm i would have thought or even an initial nock when starting from cold similar to big ends. the belt snapping seemed to have weakened 4 followers as these could be compressed and snapped 3 rockers maybe a failsafe item rather than valves or guides, cams look smooth. we thought about doing a compression test when cold and warm to try and rule out engine mechanics. But when cold its quiet and pulls smooth and strong. When warm its like an old type diesel clank noise less like a single cylinder more like the 4, until it eventually starts missing and erratic idling. the original injectors were 03L130277s but when they failed we read these could be replaced with 03L130277B so we ordered the 4 x 03L130277B refurbished and coded with VCD's and pressures appear to be equal within 0.2-0.4mg if i recall.

A bit out of my depth here but I know the engine changes injection angle at some points during warm up. Worth checking if those changes effect the performance.

Attachment 37861

Hi Roverfan, thankyou also for your help, the timing is a pig to do, what we did is with the head off and the rockers removed lay camshaft on the inlet side with a tight fitting wedge at the rear so no movement (hole at the top) and on the exhaust main primary drive cam used a cross laser level making sure that the key is at the top and in hopefully perfect alignment with the hole at the bottom under camshaft, then with this at 90 degrees the other 90 degree line was level with the head face line as seen here. then I marked the teeth that meshed so as not to go through this again, the cam pulley also lines up with the hole used when installing the belt at this point if i recall. then after that gently lifted cams and fitted rockers and rechecked alignment after camshaft cage torqued down. This is the correct tool which is ridiculous price - Common Rail Diesel Camshaft Installation Kit - VAG, Porsche | VSE7171 | Sealey - Common Rail Diesel Engine Camshaft Installation Kit (VSE7171).

So we did a cold compression test to gauge if there is anything adverse or difference between cylinders, the readings were all the same within a few PSI 380PSI / 26-27 BAR the engine starts straight away no cranking over and over again. Elsawin states the Engine oil temperature min. 80°C and Battery voltage at least 12.5 V.
Specified results - New 25.0 … 31.0 BAR , Wear limit 19.0 BAR, Maximum difference between cylinders 5.0 BAR.
So I'm thinking we shouldn't be a million miles away when hot. I'll keep you posted on our findings.
Crasher - we're tempted to take the sump of for piece of mind as you suggested not expecting to find anything but for the sake of a few bolts what's the arm. Also wondering if anything on the EGR side causing the erratic idle as the engine note changes near running temperature.
But all this from a Cambelt weird i asked my mate who owns the car if anything was damaged around the belt area sensor wise, nothing i could see when we rechecked also i would expect to see a fault appear.

Ohh don't talk about wired, I have given up worrying about odd things that happen and why, I just fix them

Hi, Well just thought i would write an update as to the findings here. So after checking what we could a cheap engine came available online so my friend snapped it up with lots of donner parts, now we were hoping this would narrow down the fault. The owner assured us no noise or smoke and running well. So now we decided that we would change the engine out of frustration as no faults showing up on VCDs.
So replaced engine with the following Cam, crank, oil, HP Pump, Alternator, started well tick over sweet until warm same symptoms. So we then started with a Complete New ERG after we found the Diaphragm had a leak. Swapped out the EGR N75 solenoid ( but existing tested OK) EGR VACUUM SYSTEM SOLENOID (This also Tested OK) changed the Exhaust pressure sensor, Still the same problem. When warm It seems to make a loud diesel clank noise and then after a bit a dull clank noise almost sounds like a petrol and then back again, its really strange. Injector amount deviation seems to fluctuate on all injectors at tick over when rough at idle at temperature from -1xxxx to +2xxxx when rough idle I'm assuming its trying to correct itself. Rail pressure and sensor showing around 26 Bar at tick over,.
So far we haven't changed the..
front and rear Temp sensors - these were showing on VCDS as coolant temp =55c, Coolant at temp outlet 26c, Sensor for engine block =55c
fuel temperature sensor
Turbo solenoid - cant see that being at fault.
MAF sensor
MAP sensor
Oxygen Lambda Sensor
Exhaust gas temperature sensors.
Throttle body
Any positive suggestions appreciated

Just been in my Garage and ran the car from cold up to temp and recorded the details from VCDs video at different stages so hopefully you can hear the engine sound also its uploaded to Y'tube so if anyone would care to peak and advise it will be appreciated. Or if you would like me to run any further tests on specific items that you may think will help please let me know. VW Passat 1.6TDI (CAYC) at temperature erratic part 3 - YouTube . there seems to be deviation of injectors, these were coded to the car after being refurbed as mentioned earlier.

I am confused as to which HPFP and injectors are in there.