After doing extensive research and stumbling upon the recent warm start rattle and talk of oil check valves I thought there might be something there. So I ordered up new oil check valves and associated parts ( oil jet, oil filter gaskets, and valley pan gasket) and began to tear into the beast.
Here are the parts required
2 x Oil check valves - 079103175C
1 x Oil spray jet - 079115540A
1 x Valley pan gasket - 079103161D
1 x Oil filter housing O ring (double D) - 079115111A
1 x Oil filter housing O ring (single O) - N90959701
Thanks to member crc for this information.
Your box of shiny new toys should look like this
The work wasn't bad at all, took me 4 hours, taking almost half of that ensuring the surrounding area of the engine was clean to prevent anything from entering the motor.
Simply start off by removing the intake manifold. You should look something like his when done.
Follow this by removing the PCV plumbing behind the manifolds location to get room to remove the oil filter housing. You don't have to do this, however it makes it much easier to work.
After it has been removed you will undo the oil filter housing. I recommend to first take the oil filter cap off and remove the filter. This will make the mess much smaller, as some oil will pour out when removing. After this, proceed to removing the housing. It is held in place by two 6 mm allen bolts in back, and 2 torx 27 in the front.
You should now be here
Take some time to get the area clean as possible. You don't want debris falling into the crank case while removing the valley pan.
After this cleaning things up you'll also want to remove the two passenger knock sensors, each held in place with 13 mm bolts. A close up of one in case you're not familiar with them.
After those are out your free to unbolt the valley pan, held in place with torx 27 bolts. Make sure to clean out any grit or dirt that may have accumulated in the heads of the bolts to prevent stripping!
You may now remove the valley pan. You'll want to lift from the side you removed the knock sensors from, and out it goes.
Underneath the pan you'll see the gasket with a ton of oil holes. (pic taken during reassembly hence the lack of oil.)
Pull if off and now you're there.
WELCOME TO THE THUNDER DOME!
The oil check valves are located in the bottom right hand corner which controls oil flow to the driver side of the head, and towards the top off center to the right for oil flow to the passenger side head. Just to clarify I am referring to the cross looking things in the pics.
Directly below the upper check valve is the oil jet btw as seen here.
Now the purpose of the oil check valve is to allow oil to flow in only one direction for the purpose of keeping oil in the head of the engine. They are spring loaded to close when there is no oil pressure.
To remove the check valves simply grab on and pull. They should just pop out as they just held in place snuggly from the o rings.
Here is the passenger side head check valve from my vehicle. It seemed to be fine, no signs of wear of sticking.
Here is the driver side head check valve. Hmmmmm
I was happy to find it seized open. The oil was not being retained in the driver side head due to this causing the nasty warm start rattle. Any oil that was in the head would just drain back into the crank case as a result.
Simply pop in the new ones after this and start everything in reverse order.
Only thing I will throw out there is to pull fuse 28 while starting the car after this to ensure oil has been pushed back into the oil galleys and prevent a nasty dry start.
SO what should you take from this?
I'm not saying this is the holy grail solution to warm start rattle, however in my case it was. I want to share my findings from my experience so if someone does suddenly developed warm start rattle and wants to explore the possibility that your problem may not be timing chain related, well you now have an option.
The way I look at this is the bad check valve may be what causes the timing system to fail in some cases (thinking the guides from the chain slapping on start anyways.)
Lastly, this may also explain why Audi states to not replace tensioners for start up rattle as they claim it won't solve the issue. Just my theory.
I hope my findings can help other members.
List of members who have performed this and results
I will list the following information so we can track to see how well this "fix" works.
Rattle gone: the car no longer rattles on hot or cold start...
Rattle warm: the car still rattles on warm start, but not on cold start
Rattle cold: the car still rattles on cold start, but not on warm start
Rattle reduced: severity of the rattle has diminished
No change: no change in rattle
I know that I may sound like Captain Obvious, but I just want everything to be clear on definitions :)
p3u---------------rattle gone
crc----------------rattle gone
dolphin B6 S4----rattle gone
If any member performs this please post the results or PM me and I'll update this list.
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