Cold start rattle 2-3 seconds then gone.

[Cmamainer]

I'm at a loss up to this point, It seems like oil is completely draining from the vanos after engine is shut down for awhile. I tried a new accumulator but that didn't change anything, but like yourself it runs great and pulls hard with no check engine light?

[BigLooga]

In my case the rattle was present prior to the vanos upgrades and in fact the original vanos was in excellent condition with very little wear on the chain guides w/no visible issues. So its still unresolved to this point.

Cmaminer, you have a similar problem? For me, im almost tempted to exclude vanos as the sound is more like a knocking, like a piece of metal knocking on another piece of metal, the noise follows the rpm's and i'm almost tempted to say that it sounds like its coming from the cams turning and then poof the noise disspears, litteraly 2 seconds. The vanos having a broken tab IMO does not generate this sound and if oil flow was a problem with VANOS then technically i would probably see some sort of performance variations, which i do not, the car pulls strong all rpms, no check engine or stored codes.

I'm tempted to pour some oil straight pipe into the oil cap just prior to a cold start to see if maybe it would fix it "temporarily".

Im also tempted to exclude the timing chain and guides as the knock i'm hearing i just can't see how it would be generated by a chain or a chain slapping against a piece of metal or plastic. My sound is definately some hard noise, ala hard piece of metal hitting another hard piece of metal and not a "soft" noise such as a chain "lashing" sound, hard to describe. A video would almost be perfect for this, i'll see how i could try to upload a video of my issue.

Thanks for the feedback

[Cmamainer]

In my case the rattle was present prior to the vanos upgrades and in fact the original vanos was in excellent condition with very little wear on the chain guides w/no visible issues. So its still unresolved to this point.

[sapote]

Many people didn't notice any noise during running until removing the guide and found it was about 1" shorter as the bottom tip worn and fell off. With a broken bottom tip, the tension has to extend further to push the same pressure on the chain.
Cold engine: takes more time to fill the tensioner
warm engine: tensioner was partially filled and less time to fill up.

[BigLooga]

Since Vanos has never worked on, I assume the upper right chain guide is original and could be worn and broken by now. Don’t know if that broken guide can cause more loose chain at startup, but sure it cannot be tighter.

True, but then if it would be the case of a broken guide, wouldn't it make noise during all starts, not only cold. And it would probably be noisy during operation. I mean my car is not that noisy, the S54 is not really a quiet engine, i didn't really notice any other noises other than the cold start noise. Thanks for the opinion, do you know if there is a way i could check for a broken guide? Not really down to pull the pan, just did a oil change, looked at the oil and didn't find any debris and also filter didn't show any foreign objects.

Thanks.

[sapote]

Since Vanos has never worked on, I assume the upper right chain guide is original and could be worn and broken by now. Don’t know if that broken guide can cause more loose chain at startup, but sure it cannot be tighter.

[BigLooga]

It either sounds like something is getting starved of oil or takes a second to settle. I would check that main tension guide. Sadly the Vanos has to come out to see it but it's probably broke. Something like a clogged filter could be stopping the Vanos from getting immediate oil pressure. Have you gotten your exhaust hub squared away or is everything still stock?

Stock Vanos for me.

Well, if that would be the case of lower oil pressure then i would probably have a vanos issue but the power at all rpm is good and there is no lag or noticable power issue. From what i read about the vanos "lockdown" by changing the hub with tigher cleareances i just don't see my issue as being a symptom of a bad hub or broken tabs. Thanks for the suggestion, i'll continue to monitor the situtation.

[Arith2]

It either sounds like something is getting starved of oil or takes a second to settle. I would check that main tension guide. Sadly the Vanos has to come out to see it but it's probably broke. Something like a clogged filter could be stopping the Vanos from getting immediate oil pressure. Have you gotten your exhaust hub squared away or is everything still stock?

[BigLooga]

Ended up doing my first cold start after oil change and the problem is still there but maybe a little... Meh, i'll update if it worsen or gets better out of the blue as it did appear out of the blue also.

[BigLooga]

I have this same issue, have changed the chain tensioner, accumulator and did the full Beisan vanos rebuild. Only does it on cold start, sounds normal on warm startup?

I see. Yes, for me it only happens on a cold start (overnight or 8hours lets say). I have changed the tensioner, it did not solve the issue, i just changed the oil last night and today will be my frist cold start since, I doubt the oil has nothing to do with it but it was just wierd that this happened after my last oil change.

[Cmamainer]

I have this same issue, have changed the chain tensioner, accumulator and did the full Beisan vanos rebuild. Only does it on cold start, sounds normal on warm startup?

[Mr.wReckless]

IDK but if it sort of is VANOS oil pressure but not the usual VANOS rattle then maybe it's worth looking into changing the VANOS oil pressure accumulator? Relatively easy DIY.

[BigLooga]

I got around installing a new timing chain tensioner, it did not solve the issue. The install was kinda of a bitch to install as you need a specific 32mm socket so i had to customize my socket (chop it about 1/4 inch). The old tensionner was the original one (2004) and maybe it was not faulty but it was definately stiff and had almost no play in it anymore. The noise does seem to come out out of the top of the engine, almost near the vanos but it's hard to diagnose as it only happens on cold start (8 hours between starts) and only lasts about 2-3 seconds then it's gone. I will continue the search.

[sapote]

Makes sense Sapote. There is no exterior leaks, do you know if the check valve inside the tensioner is something that can be repaired if damaged or i'd be best replacing the tensioner? Thanks.

I don't remember exactly how to access the check valve, but I think once the plunger is pulled out then you can see the check valve by following the oil feeding hole on the side of the tensioner body.

[jet_dogg]

Lol no, need to buy.