T5 CAAC engine - Loud knock, conrod bearings?

[fekillix]

Hi everyone.

I bought a 2011 T5 a on an auction a long while ago with a "small engine problem, probably the injectors". It has done 220K km. Worst purchase of my life

It wouldn't run when I bought it. Had been sitting for a while. After some disassembly I found that the HPFP had sent shavings into the injectors. It has now had the fuel system cleaned, HPFP and injectors replaced (and coded).

Now it starts right up, but when it runs it knocks . Here is the video. The intake is off to eliminate turbo/EGR, and the aux. belt is off to eliminate AC compressor, power steering pump and alternator.

• When I had the injectors/HPFP out I took off the valve cover. It looked clean.

• When I replaced the HPFP I changed the timing belt. The old one was still in time, and had previously been replaced at the right interval (but was again due)
• No (engine) fault codes in VCDS. I did the "compression test" in VCDS and the result was even over all the cylinders.
• No smoke from the exhaust, combustion seems clean. Oil filter doesn't look abnormal, can't see any metal flakes. Not much blowby either.
• No service history. Since there was no "sludge" in the top end and the timing belt was replaced on time I think it has had a decent level of maintenance.

I have three suspects for the noise.

• Noise coming from the conrod bearings (new engine?)
• Noise coming from the valvetrain (new head?)
• Noise coming from the clutch/flywheel, which was supposedly replaced 20K km before I bought the van (no change in noise with clutch in or out).

What do you guys think? I'm a bit at wits end with this van. Not sure if it's worth it to put in a reconditioned engine (especially without pinpointing the cause) but I've already spent $$ on the HPFP and injectors.

I count roughly 15 taps per second which corresponds to the idle speed of roughly 900 rpm. So one tap every revolution. Then it should not be from the camshafts as those spin at half the crank speed?

Thanks and best regards

 

[manfrotto]

Rattling DMF ?

 

[fekillix]

Rattling DMF ?

I suppose it could be. Could that happen with a bad install on a new flywheel? I know the clutch swap was done by an amateur since the reverse and neutral switch connectors on the trans look just as nackered as all the other ones on the van that have been touched before. There is also a plastic dust seal on the end of the bevel box that they forgot and had to bend/break to get it onto the output spline after they put in the front subframe. (This one)

 

[Sasquatch]

If a hamateur did it they may have thought they were being clever and re-used to,old DMF. We've known garages daft enough to do it.

 

[DXX]

Just because it was invoiced for a now DMF doesn’t mean there is one.
Not sure how many miles since the last oil change service, if enough a Millers oil analysis will be a good indicator as to the state of the engine wear
An oil pressure check is also advised before spending more cash.
Briefly running with a more viscous oil may reduce the noise and point to a bearing failure.
Some talent on the end of a good stethoscope would be a good move

 

[manfrotto]

Does the noise sound louder from underneath (with the sump gaurd off) or as @DXX says try and Stethoscope to narrow done where the noise is coming from.

Any other symptoms other than the knocking noise? worse when engine cold/hot etc.

 

[fekillix]

Appreciate your responses, a bit of an update:

I bought a stethoscope. It's quieter when listening to the transmission housing and louder on the sump. So probably not clutch/flywheel. Sounds about the same listening to each injector. Sounds the same at startup and after 10 minutes idle.

After running the engine a bit more, I got a fault code! Misfire cylinder 1. I pulled injector 1 and 2 and swapped (and coded) them over. Not much difference, I haven't gotten the error message again after swapping the injectors but it will probably come back if I run it longer. Looking at the injector deviation after swapping the injectors it looks like something is up with cylinder 1.



When I had the injectors out I took the opportunity to scope cylinders 1 and 2 with a (very cheap) boroscope that fits the injector hole. The piston in cylinder 1 has less carbon than cylinder 2. There is no sign of piston-valve contact. I rotated the crank and I can see that the intake and exhaust valves on cylinder 1 are fully closed when they're supposed to and open when they're supposed to.

It does however look a little bit like the two exhaust valves aren't quite in tune, one appears to close a tinge later than the other. Maybe it's the wide angle lens and the camera being a bit off center, hard to say. Looking at the intake valve picture it almost looks like it's the same thing there. I didn't see/notice this when looking in cylinder 2.



I then added some oil-thickening conditioning goop while running the engine. No noticeable change in noise. Noticing some blowby, and a tinge of white smoke when opening the filler cap.

It sounds worse when giving it gas.

So what I'm thinking now. Measuring the oil pressure would be nice, but it requires a new tool and is tough to access. I could also remove the sump to inspect the oil strainer and maybe the conrod bearing shells, but right now I think it is a cylinder 1 issue, although I don't quite understand how this would cause such a loud knocking sound.

I bought a compression tester I wanted to use when I changed the injectors, but it didn't come with the right injector port adapter. Now I'm thinking it may be worthwhile to remove the glow plugs and do a compression test that way (I hope the glow plug adapters fit), to shed some more light on the valves possibly not closing in order.

What do you guys think? Take the risk in removing the glow plugs and check the compression, or is there something else I should do first?

 

[DXX]

I think a compression test will reveal insufficient compression on C1.

 

[catfood12]

That's not a DMF noise. DMFs are more rattley and not always constant with revs etc. From the first video that sounds more cammy than anything else. I think the noise on the video when you rev it is being masked by other booming noises, did you have the exhaust off or similar?

If cyl 1 is the suspect, pop the rockers out and see what happens. Also if you added thickener and it was big ends, I would expect to hear a difference, for at least long enough to get it to the auctions!

 

[FWhite]

What about using the van as it is? Put it together and run it a couple of weeks? When it will break it will break and you may find it out. But it might not and you could enjoy another 100k km on it, that are possibly worth your investment. Just thow away that tainted oil and put in the good one again. All my Renaults were similarly noisy even by new! In fact now I am surprised about how silent the TDI is.