Warm start rattle solved on my car!

[p3u]

So a quick back story, for about the last three weeks my car out of no where started the dreaded warm start rattle. I thought the tensioner had gone out. Oh my luck I thought.

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.


UPDATE!!!!


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
No change: no change in rattle

I know that may sound like Captain Obvious, but I just want everything to be clear :)


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.

[Denker]

Glad you got your rattle sorted. I think the logic behind this, chain on guide contact at start up due to lack of oil retention, makes the most sense to me. Nice write up.

[B00sted20VUSP]

Awesome info

[SpoolBus]

Good deal

I wondered who coined the term "chain rattle" as its more of a "crunch"...but "rattle" is easier on the ears I guess

[rixonichard]

Could it be that failure of the check valve is also the cause of cold start chain rattle, or does the valve only retain the oil for a short time, thus not affecting the engine when cold? I've read many threads of guys who've replaced tensioners or had timing components replaced and have reported that the rattle was diminished but not eliminated. Could it be this one little part is the culprit?

Has anyone on here ever had chain rattle and not had a bad check valve? I'm fascinated by the possibility that all or most timing component failures could be related to this. Very interesting.

[R&Cs4]

So after you did this replacement, did your warm rattle go away completely?

[R&Cs4]

And btw the part number for the single o o-ring is N90959701

[p3u]

So after you did this replacement, did your warm rattle go away completely?

Yes, the failed valve caused there to be no oil in the tensioner when started hence the noise. Now that oil is retained the problem is gone.

[dparm]

What was the car's maintenance history like?

Internals have varnish, but otherwise look good.

[p3u]

What was the car's maintenance history like?

Internals have varnish, but otherwise look good.

Car has always had oil changes between 3-5k miles. There is not varnish, you see the boundary layer of oil in the engine.

[TarlCabot]

This is GREAT info, thanks for the write up p3u

[R&Cs4]

I've been getting warm rattle as well, so Jimmybones and I are going to test doing this on my car as well in the next couple of weeks. Will post results here.

[IslandHydro]

This is very interesting. I have highly intermittent rattle, 1 out of every 50 or 100 starts. Perhaps I have a check valve that is occasionally sticking? Look forward to what you find R&Cs4!

[bioluminescent]

Good job. Were you getting warm rattle every single time, or just occasionally? Were you also getting chain rattle on cold start ups, and if so has that changed at all?

[B5man17]

I might have to try this I get the ever so slightly rattle, and I'm doing intake spacers so mine as we'll do it when I have the intake off.

[jmcS4]

Good job. Were you getting warm rattle every single time, or just occasionally? Were you also getting chain rattle on cold start ups, and if so has that changed at all?

THIS, need feedback please. Im gonna try it as well

[dparm]

Car has always had oil changes between 3-5k miles. There is not varnish, you see the boundary layer of oil in the engine.

Thanks for clarifying. Looked like varnish in the photos. Things obviously fail over time -- glad to hear this wasn't something catastrophic.

[mankytron]

This is great info and should be #1 to check before investigating timing components. Thanks for posting.

[Slow4]

Were you also consuming more oil than normal, as well?

[p3u]

Were you also consuming more oil than normal, as well?

Not at all. My car has never burned oil, lucky on that one.

[mistral cytz]

This is very interesting. I have highly intermittent rattle, 1 out of every 50 or 100 starts. Perhaps I have a check valve that is occasionally sticking? Look forward to what you find R&Cs4!

I seem to have just the odd day where I get warm start rattle every few starts and then in goes away for weeks. Could be logical that these valves get stuck open sometimes. This thread is very interesting and I hope you're on to something big for the sake of all S4 owners!!

[p3u]

Good job. Were you getting warm rattle every single time, or just occasionally? Were you also getting chain rattle on cold start ups, and if so has that changed at all?

Every warm or cold start I'd get the horrible rattle. Now 100% gone!

[p3u]

Here are a couple diagrams I used for replacing the valves. Hopefully these are useful.

[dolphin B6 S4]

First I'll note that I have approximately 1,750 miles on my new timing components. B00sted20VUSP and I replaced these on my car tonight. BIG thanks to him, he did almost all of the work while I cleaned, and did an excellent job. In this case my valves weren't actually stuck open, but my car warm start rattled about 9 out of every 10 times so we'll how this works. We took it for a spin after installation to get it up to operating temperature, then let it sit for ~15 minutes (which I found was the perfect wait time to achieve a lot of warm start rattle), and sure enough when we started it there was no rattle . I'm really exited to see if this was the solution, I'll keep you guys updated. Pics for fun

[crc]

Thanks to member crc for this information.

Hey p3u, good to hear the parts list worked. A little research looks to be treating the members here well! Might even be time for a formal DIY if this solution keeps working for everyone.

My rattle is non-existent now, all I hear is the air con clutch engaging, which I must admit I was confusing with a start up rattle for a while there. I could tell that was what it was by starting the car with the air con in ECON or OFF.

[p3u]

Awesome news dolphin B6! I hope it did the trick for you!

Mine was the same way, anything longer then 15 min and rattle.

[p3u]

Hey p3u, good to hear the parts list worked. A little research looks to be treating the members here well! Might even be time for a formal DIY if this solution keeps working for everyone.

My rattle is non-existent now, all I hear is the air con clutch engaging, which I must admit I was confusing with a start up rattle for a while there. I could tell that was what it was by starting the car with the air con in ECON or OFF.

Indeed! Don't want to get too ahead of ourselves but holy crap if this little valve is the source of many people's problems! How is this not something widely known?

Perhaps we should make a list of people who have done this and result to gauge it's effectiveness.

[averyel]

Awesome writeup.

[Mr. Corey]

Nice thread OP!!!!! Is this a good preventative thing while upgrading intake mani and spacers...? Seems like its not to much more work after your already their? How many miles you at if you dont mind me asking? Glad to hear its helping out with other members cars!!!!!

[Quadfreak]

OP...sorry if you said this already, but are you on your original timing components? I have cold start rattle and very seldem warm start rattle. And am wondering if this is something worth doing even with my original timing components.

Also, I am honestly surprised no-one has figured this out sooner..

Sent from my HTC6435LVW using Tapatalk

[FWP!]

This is actually pretty fantastic news, thank you for posting and doing a great writeup!

[B00sted20VUSP]

No problem Dolphin B6 S4! Garage nites are fun! I hope it helps the rattle, so far so good and Im sure he'll keep us posted. Anyway big thanks to p3u for the write-up. Like Dolphin said his check valves were NOT stuck open when we pulled them out, that doesnt mean that they wern't sticking when warm or just a weak spring. This is a good peace of mind though. His car was pretty loud when restarting warm (2-3 seconds of rattle). And like he said he has all NEW timing components that were done at our shop. I'm a 12 year Vw/Audi tech and have never heard anyone replacing these before. Good info for the B6/B7 S4 community!

[dparm]

So what was the specific failure mode? You said it was stuck open -- did something break/fail/pop loose? Just curious how the part operates and why it would fail in a way that actually prevents the oil flow.

[B00sted20VUSP]

Its just a spring loaded check valve. One of p3u's were stuck open when he pulled it out. Like the OP said these are oil retention valves that keep the oil primed in The upper part of the engine (cylinder heads and chain tensionors). When the engine is running they are opened by the pressure of oil so oil can flow everywhere. When engine shuts off, oil pressure goes away and these valves close frome spring pressure inide of them thus keeping oil from draing back to the oil pan, keeping everything primed.

[QIKRNU]

So what was the specific failure mode? You said it was stuck open -- did something break/fail/pop loose? Just curious how the part operates and why it would fail in a way that actually prevents the oil flow.

Like a thermostat, you want it to fail in the open position.

[B00sted20VUSP]

So what was the specific failure mode? You said it was stuck open -- did something break/fail/pop loose? Just curious how the part operates and why it would fail in a way that actually prevents the oil flow.

When it fails it doesn't prevent oil flow, it prevents the oil from being held in the upper part of the motor. The reason it causes a rattle is that the engine has to reprime all the oil passages and tensionors on restart, kind of like after you change your oil you hear everything priming for a brief couple seconds when you first start it.

[p3u]

Nice thread OP!!!!! Is this a good preventative thing while upgrading intake mani and spacers...? Seems like its not to much more work after your already their? How many miles you at if you dont mind me asking? Glad to hear its helping out with other members cars!!!!!

It could definitely be a preventative item. I personally think you could wait till you start to hear some rattle before jumping into this, if you're installing some intake spacers like mentioned then why not.

My car is at 108k miles.

[p3u]

OP...sorry if you said this already, but are you on your original timing components? I have cold start rattle and very seldem warm start rattle. And am wondering if this is something worth doing even with my original timing components.

Also, I am honestly surprised no-one has figured this out sooner..

Sent from my HTC6435LVW using Tapatalk

It's a good Q I haven't answered. I am on original timing components in my vehicle. Prior to replacing this I'd occasionally have a cold start rattle, maybe once a week, and once the warm rattle started 3 weeks ago every time after the car had been off for more than 15 min.

[p3u]

No problem Dolphin B6 S4! Garage nites are fun! I hope it helps the rattle, so far so good and Im sure he'll keep us posted. Anyway big thanks to p3u for the write-up. Like Dolphin said his check valves were NOT stuck open when we pulled them out, that doesnt mean that they wern't sticking when warm or just a weak spring. This is a good peace of mind though. His car was pretty loud when restarting warm (2-3 seconds of rattle). And like he said he has all NEW timing components that were done at our shop. I'm a 12 year Vw/Audi tech and have never heard anyone replacing these before. Good info for the B6/B7 S4 community!

Since they weren't stuck open just curious if you tried pushing on the plunger to see if it felt though to move or sticky?

[mistral cytz]

So replace these check valves and the results are that it prevents oil pressure from dropping off in the top of the engine where the adjusters are so that the tension on the chains is maintained resulting in no chain play rattling on the plastic guides? Have you noticed that changing these check valves has also reduced the cold start rattle at all??

It would be just incredible if this would fix our timing problems! I'm not assuming anything yet, but could you imagine if a fairly straight forward DIY job that takes 3-4 hours could replace a multi thousand $ job of removing the engine and replacing the shit timing components in our cars!

Even if it only takes care of the warm start rattle, that is still significantly reducing the number of times the guides are stressed from an initial start up meaning the eventual timing component job could be at least be extended to a higher mileage for many engines.