Timing chain rattle Audi A7 3.0tdi

[Abarth_1200]

Audi 3.0 V6 TDI timing chain rattles at startup after it's been sitting for more than a couple hours. Currently 111,000 miles with what looks like a 10-15k service interval previously. The engine pulls well and is quiet between 1-2 seconds after startup, I feel I have diagnosed the rattle issue correlating to the top most tensioner draining down the oil after sitting for a while.

I did a quick oil change as it was nearing 6k miles since it's last service and used liquimoly proline engine flush and then Castrol edge 5w30LL vw 507 spec oil. I filled it with nearly 7 litres (after checking the electronic oil level display on dash a few times to get to 90% of max level) when the book called for 6.3L. I extracted roughly 6.5L. The oil was black as expected and thin.

Still have the rattle, sometimes it doesn't though.

Questions I have are additives to help the top tensioner hold oil pressure, or at least get oil faster upon startup.

I have bought some liquimoly hydraulic lifter additive in the hopes that this will do a good job, but now after finding this forum this just seems to thicken the oil. Hence why Ive signed up and is though to ask. I was originally going to pour 2 cans of ceratec in and run it for 3k miles or so and then oil change again. But maybe I can try the hydraulic lifter additive first as it doesn't appear to add anything chemically to my engine.

Thank you for reading

 

[Vil_Riker]

I have A6 with the 3.2 l engine and it has had the startup rattle for 200k miles. Audi thinks it's normal. Basically, the tensioner drains of oil when the engine doesn't work.

I do 5k OCI with Mobil1 or LiquiMoli to try to keep the tensioners in good shape.

 

[twX]

If there is an oil screen on the tensioner, it could be a bit gunked up. You could try using a cleaning additive, or short OCIs with an oil that is good at cleaning. Using an oil of a different grade won't make much of a difference if it's happening over a wide range of cold start temperatures.

What oil filter are you using? A restrictive filter might make the issue worse, since it'll cause the oil pump to bypass more oil, and reduce the flow rate. I assume you have a cartridge style filter. If the filter housing has a built-in anti-drain back valve, it might not be working well.

If it only happens briefly on cold starts, I wouldn't worry too much about it unless it starts getting worse.

 

[Abarth_1200]

I have A6 with the 3.2 l engine and it has had the startup rattle for 200k miles. Audi thinks it's normal. Basically, the tensioner drains of oil when the engine doesn't work.

I do 5k OCI with Mobil1 or LiquiMoli to try to keep the tensioners in good shape.

Thank you for this, I take it yours is a v6 tdi also?

I just can't help but wonder how much damage is being done on startup with this rattle and if there is anything I can do other than replacing the chain which I can't afford I'll do to help it along.

 

[Abarth_1200]

If there is an oil screen on the tensioner, it could be a bit gunked up. You could try using a cleaning additive, or short OCIs with an oil that is good at cleaning. Using an oil of a different grade won't make much of a difference if it's happening over a wide range of cold start temperatures.

What oil filter are you using? A restrictive filter might make the issue worse, since it'll cause the oil pump to bypass more oil, and reduce the flow rate. I assume you have a cartridge style filter. If the filter housing has a built-in anti-drain back valve, it might not be working well.

If it only happens briefly on cold starts, I wouldn't worry too much about it unless it starts getting worse.

Thank you for the information, I'll need to google some more to find out about the screen. It does makes sense however so something to note.

It is a cartridge style filter, using a Bosch cartridge. Also to note it's located at the top of the engine. Where would I find the flow rate of a filter?

 

[Vil_Riker]

Thank you for this, I take it yours is a v6 tdi also?

I just can't help but wonder how much damage is being done on startup with this rattle and if there is anything I can do other than replacing the chain which I can't afford I'll do to help it along.

it's the naturally aspirated 3.2l gasoline engine. The recommendation for mine is to change the tensioners but for a DIY it's a little bit risky.

I just keep the OCI low

 

[wlk]

The Hydraulic Lifter additive has helped some and I have used it, so I would use it first. Then go from there and see if you need the Ceratec.

 

[Trav]

Audi 3.0 V6 TDI timing chain rattles at startup after it's been sitting for more than a couple hours. Currently 111,000 miles with what looks like a 10-15k service interval previously. The engine pulls well and is quiet between 1-2 seconds after startup, I feel I have diagnosed the rattle issue correlating to the top most tensioner draining down the oil after sitting for a while.

I did a quick oil change as it was nearing 6k miles since it's last service and used liquimoly proline engine flush and then Castrol edge 5w30LL vw 507 spec oil. I filled it with nearly 7 litres (after checking the electronic oil level display on dash a few times to get to 90% of max level) when the book called for 6.3L. I extracted roughly 6.5L. The oil was black as expected and thin.

Still have the rattle, sometimes it doesn't though.

Questions I have are additives to help the top tensioner hold oil pressure, or at least get oil faster upon startup.

I have bought some liquimoly hydraulic lifter additive in the hopes that this will do a good job, but now after finding this forum this just seems to thicken the oil. Hence why Ive signed up and is though to ask. I was originally going to pour 2 cans of ceratec in and run it for 3k miles or so and then oil change again. But maybe I can try the hydraulic lifter additive first as it doesn't appear to add anything chemically to my engine.

Thank you for reading

It is more than likely a broken chain slipper/guide, even if it were a tensioner the engine has to come out anyway. These engines are notorious for chain, guides, and tensioner issues, it is due to long service intervals 10K is too much and 15K is 3x what is ideal for these.
5-6K with a good quality synthetic Euro oil or the chain will wear and parts get damaged. there is no such thing as chain stretch, it is wear at the pins and rollers the chain side plates cannot stretch.

This job is beyond most DIY and very expensive to do, the chances of a sticking or leaking down tensioner is rare but it doesnt hurt to try whiz bang in a can, if it works you dodged a bullet. Do not put MoS2 or any other solids in these engines or any other engine that uses hydraulic engine controls eg tensioners, lifters/lash adjusters, cam phasers, etc they can plug the tiny orifices causing them not to function properly. IMO the best thing you can try is 2 consecutive oil changes with Mobil 1 0w40 with no additional additives, if it does not stop you have a big $$ decision to make.

 

[vinu_neuro]

Timing chain rattle is a common issue on Audi V6's of that generation. My experience has been that 5W-40 have done the best. The startup rattle was there every so often over 70k miles on Castrol 0W-40, more often with M1 0W-40 (along with being noisier in general operation) and less so with Castrol 5W-40. Potentially the higher base oil viscosity helps remedy this pathology.

5W-40 or any 40wt would not be possible with 504/507, but if you are willing to try a LL-04 or 229.51 oil, I think you will find some relief. A better option than using additives.

Make sure to use only OEM, Mahle or Mann oil filters for Audi engines.