“Do not exceed 4000rpm” warning message

[Ineedmoreaudi]

Hi, 
I have 2010 Audi A5 2.0 TFSI CDNC engine.
Automatic. 62k miles. 

The old style tensioner failed on it. Replaced the timing chains. Compression test was fine so did not need to take off head for valve job.

Castrol edge 5w30 LL oil used. New plugs, filters, new battery. 

car drives spot on, plenty of boost, no error codes on vcds. Sounds a tad loud at the top but they all sound like that. 

when the car is warm and I come to a stop, at idle,  I get the warning message. “Do not exceed 4000 rpm” - still no fault codes, no epc light, no engine management light. 

I am getting 1.5 bar oil pressure at idle and the sensors have been replaced and not throwing any errors.

I swapped the oil pressure solenoid (bottom of engine next to crank pulley) over with another working one that I had on the shelf but still message comes up. 

also swapped over the cam bridge. Did notice screen was broken, recovered most of it, yet a tiny piece I think may have gone through the galley but I am not sure. 

The sump had some ali shavings and gunk but not much, there were some small broken parts of the chain guide, otherwise very clean. Oil was very dirty. 
 

not much on forums on this topic and a lot of random answers too.

After a lot of reading and swapping parts over.
-I am lead to believe this broken piece from the cam bridge is stuck somewhere

-pieces of the guide maybe stuck somewhere 

-it could be oil pump,

-balance shaft,

-or non return valve inside the head. 

before I strip everything down again was hoping somebody could shed some light on this issue? 
 

Thanks 

[cliffcoggin]

My suspicion is the same as your suspicion: that there is a complete or partial blockage in one of the oil galleries. The only solution I know of is to strip the engine and reverse flush each passage with oil or water at a higher pressure than the pump makes. I imagine 6 bar would be enough.

In case you are not aware, reverse flushing means forcing the fluid in the opposite direction to the normal oil flow.

[Ineedmoreaudi]

Thank you for a quick response. 
I will try that when all is open…

[Ineedmoreaudi]

1 hour ago, cliffcoggin said:

My suspicion is the same as your suspicion: that there is a complete or partial blockage in one of the oil galleries. The only solution I know of is to strip the engine and reverse flush each passage with oil or water at a higher pressure than the pump makes. I imagine 6 bar would be enough.

In case you are not aware, reverse flushing means forcing the fluid in the opposite direction to the normal oil flow.

Any idea on how I would perform a reverse flush? Thanks 

[cliffcoggin]

I have no personal experience of doing the job, but I know it is done during engine manufacture to remove swarf and grinding dust. Presumably it also done by engine reconditioners so perhaps that avenue is worth investigating.

[Ineedmoreaudi]

1 hour ago, cliffcoggin said:

I have no personal experience of doing the job, but I know it is done during engine manufacture to remove swarf and grinding dust. Presumably it also done by engine reconditioners so perhaps that avenue is worth investigating.

Ok thanks for the advice, will update soon. 

[Ineedmoreaudi]

Hi all, so the engine has been stripped down. A few interesting discoveries.

firstly I found the vacuum pump did not have the crush gasket installed, found scraps of silicone around it. I did notice an oil leak but could not see where from when the engine was assembled. 
 

secondly the the 2 rubber O rings installed on the black spring that sits under the oil filter in the oil filter housing were completely worn. 
 

and finally the the conrod bearings have uneven wear. I don’t actually know what they should look like. I would have thought it’s normal wear but because it’s uneven it’s got me wondering. 
 

maybe one or all of these are causing oil pressure issues and the error message to pop up at idle? 
 

adding some pictures of the bearing so hopefully somebody can advise on this further. 
thanks 

 

 

[cliffcoggin]

SAJ.

Those big end shells look OK in as far as there no deep scuffs or gouges, but appearances can be deceptive. The only way to be certain is to assemble the bearings and measure the clearances between shells and journals. A product called Plastiguage can do that. You would need to find out the maximum recommended clearance from Audi.

https://plastigauge.co.uk/

The uneven wear is because most of the load on the shells is vertical. There is little horizontal load hence the sides don't wear as much as the tops and bottoms.

I can not be certain from a couple of photos, but from the evidence you have presented I think it is unlikely the big end bearings are the cause of the low oil pressure. If they were badly worn the engine would be noisy with a distinctive "big end knock", however having gone to all the effort of removing the sump and big end caps it would be worth going that little bit further to measure the clearances, otherwise there will always be that doubt in your mind.

[Stevey Y]

2 hours ago, Ineedmoreaudi said:

Hi all, so the engine has been stripped down. A few interesting discoveries.

firstly I found the vacuum pump did not have the crush gasket installed, found scraps of silicone around it. I did notice an oil leak but could not see where from when the engine was assembled. 
 

secondly the the 2 rubber O rings installed on the black spring that sits under the oil filter in the oil filter housing were completely worn. 
 

and finally the the conrod bearings have uneven wear. I don’t actually know what they should look like. I would have thought it’s normal wear but because it’s uneven it’s got me wondering. 
 

maybe one or all of these are causing oil pressure issues and the error message to pop up at idle? 
 

adding some pictures of the bearing so hopefully somebody can advise on this further. 
thanks 

 

 

Hi the big end shells are not good the lighter patches are where the coating is worn away when the oil pressure has dropped and they have been in contact with the crank journals, its quite a complex system at the bottom end the journals are always separated from the bearings by a film of oil this negates any bearing/journal contact on initial start, the oil pump pressure is almost instant and from there the bearings/journals are separated by what is known as a hydraulic wedge which keeps the two apart, on very old engines say the 1900s the bearing shells were coated with horse hair this allowed for the very inefficient oil pumps to get up to pressure without damaging the crank journal.

Steve.