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Engine Noise at Startup When Cold. Oil Drain Back Valve Issue?

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ltemup4650

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Discussion starter · #1 ·
Hello all. I have a 2007 3.6 Touareg. On startup when cold, the engine makes what I believe to be some excessive noise. After 5 seconds or so, it goes away and runs smooth. If I run around in the vehicle for awhile, say stop at wal mart or the gas station, once I restart with the engine warm (less than an hour after last running), there is no noise at startup. I'm thinking I might have an oil drain back issue. Since these vehicles have cartridge style oil filters, where is the anti drain back valve? Anyone else ever replaced one? I can't find a part, but I'm sure there has to be one. Is it part of the oil filter to block assembly? I recently replaced the timing chains, guides, and tensionsers (the internal one and the passenger side bolt in one).

Thoughts?

Thanks.
 
Discussion starter · #3 ·
Did you use correct oil standard and weight? Answer: YES
Did you change out the filter? Answer: YES

Collapsed hydraulic valve lifter. Answer: NO. collapsed lifter tick and typically don't go away after start up. When they to fill back up with oil, the ticking goes away and a lot of times doesn't come back.

Hydraulic tensioner inspected? Answer: As stated above, both were replaced.
 
#4 ·
This can be normal, but is more typical or pronounced with Mobil 1 0W30. Try a heavier oil like 5W40 and see if it lessens. I have had this since day one (now at 100k miles) no material change. I use Pentosin 5w/40 and have this too, but for two seconds only and not every time.

Outside of using heavier oil that isn't as thin as water (ok exaggerating, but pretty thin) when cold, there is nothing else you can do.

People have spent BIG money trying to fix this. There is no fix, it take a few seconds to build oil pressure and light weight oil extends that.
 
#5 ·
#7 ·
ltemup4650 said:
built4sin,


Thanks for your input! Both of those threads, however, are for the V8 model. I have the 3.6 VR6. I'll have to do some digging and see if the VR6 has similar check valves.
Click to expand...



Had to bump this thread.

I have a 2011 VR6 Treg and noticed the noise at startup that goes away also. Did you find any resolve for yours? Are there check valves that can be replaced to stop this noise and sometimes shakiness at cold startups?
 
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#8 ·
New2Tregs said:
Had to bump this thread.

I have a 2011 VR6 Treg and noticed the noise at startup that goes away also. Did you find any resolve for yours? Are there check valves that can be replaced to stop this noise and sometimes shakiness at cold startups?
Click to expand...
Probably normal. The timing chain tensioners (2) rely on hydraulic pressure to work. At initial start up slack in timing chain will cause a rattle that should go away quickly once oil pressure is built up. The upper tensioner is accessible passenger side of block . Essentially a bolt with hollow core which contains a piston that pushes against chain guide bumper to take slack out of chain. Want to keep a healthy chain don't let oil get to dirty as the tensioners will not function as they should. VR6 in general hates dirty oil.
 
#9 ·
New2Tregs said:
...and sometimes shakiness at cold startups?
Click to expand...
The shakiness is likely a phenomenon of the first generation technology used to rapidly heat the cats. The process sounds made up, but it is really called "The Homogeneous Split Catalytic Converter Heating Process" Fuel is injected as normal, but then right before ignition TDC, more fuel is injected resulting in a rich mixture that is very hot being blown down into the exhaust to preheat the cats. This in my mind is the reason for the odd shack or "off" feeling you get when the VR is cold. This was new technology when used in the VR, it has likely changed or improved with more modern engines, but remember this 3.6 is a very dated engine now that remains largely unchanged from the first 3.6 back in 2005 (first offered in the Passat I believe).
 
#10 ·
Alright, I have to start this thread back up again. I have pretty much the exact same scenario as the OP, and I can't see an answer to Itemup4650's question.

2007 Touareg with 3.6. Recent timing chain job with all assorted parts. I noticed about a month afterwards that it was much louder on startup. This would go away after 5-10 seconds and sound normal when the engine was warm. This may seem like the "normal initial startup noise", but I assure you that the Touareg DID NOT sound like that before the timing chain job.

Anyway, recent update is a warning for low oil pressure/stop vehicle. I immediately shut it off, and checked oil. The oil level was definitely high. I've checked the oil level about every 2 weeks and have never noticed it being high. So... what gives???

Basically, that's why I'm asking about the anti-drain back valve. Could a failure be why there is (1) startup noise, and (2) elevated oil level on the dipstick?

Any input would be greatly appreciated!
 
#11 ·
The VR6 has a plastic holder on the inside of the filter. There are 2 different oil filters. One with a prefix A and one without. Make sure you have the correct one! VIN will tell you which one to get!
 
#13 ·
Low oil pressure can also be triggered by a torn pcv diaphragm. On the 3.6 you will have to remove the valve cover to check. You don’t need to replace the whole valve cover. This company is selling the diaphragm only.




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#14 ·
Thanks for the input TRespect. I replaced my pcv diaphragm with that kit in January (due to fluctuating idle, but no oil pressure issues then). I contacted my local VW dealer to verify the correct oil filter, but of course they aren't answering in the parts dept. From what I can tell online, I do have the correct one installed.

The noise began during a trip to the mountains a couple months ago. Interestingly, it was after going up Pikes peak and then down at night while camping it got to near freezing. I wonder if the plastic on the filter became brittle/cracked because temps were extremely high on the climb and then got near freezing overnight. Just a thought. I'll change the oil/filter and update soon.
 
#15 ·
If it happens during deceleration it is most likely a torn pcv diaphragm. Just keep that in mind and if the pattern is confirmed then you need to go back to the pcv and check everything is ok. I had this happen on my Audi and the Treg. Floor it to 5/6000 rpm and apply the brake.


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#17 ·
Another thing to check: brake booster vacuum hose. If you have a leak there you might suffer from pressure loss when braking. I’m investigating a similar issue on my 3..2. I have a fuel trim rich code and I strongly suspect that hose or the two check valves on it. I will post info about the 3.6 vacuum system later.


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#19 ·
If this happens when you brake it’s either the pcv valve not closing the path from engine block to intake for some reason or a check valve or leak issue in the intake hoses. A possible scenario would be:
You apply the brake
Vacuum pulls down the pcv diaphragm against the spring and closes the path from engine to intake.
Two causes I see for it to fail:
1. Pcv diaphragm is torn so pressure continues escaping and you have the warning.
2. Vacuum pulls down the pcv diaphragm but since there is a vacuum leak the pcv diaphragm is not pulled completely down to seal or block the pressure path from engine to intake. Pressure continues to escape. Hence the low oil pressure.
There are the traditional causes like a bad pressure sensor or clogged oil passages, oil filter or oil pump. Make sur the oil dipstick is seated firmly too.
And I might be completely wrong of course :)
I will try to find a link which explains in details how the pcv works.


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