Start up rattle

Every time when the car sits for longer than a week, when I start up the car there is about a half of a second of rattle, like the valves are not getting oil.... should I be looking further into this? or is this normal?

Mine does the same thing but it doesn't seem to affect anything.

ditto

Mine does it when I turn the ignition off. WTF???

Are you sure the noise is coming from the engine? I had a similiar problem that I thought was the muffler or engine. My 1999 c2 rattled every morning when the car was cold. Turned out to be the heat shield that wraps the back end of the car behind the bumper. I pulled the rear bumper and had a friend stand at the back of the car to pin-point the noise. A piece of the heat shield was loose, so we riveted all of the overlapping pieces of metal together so they wouldn't vibrate. Car is now quiet upon cold startup and hasn't made a noise since. Hope this helps. Nick

I was thinking of a heat shield, but it's only for that half of a second after long periods of sitting...I drove Friday night and it rattled. Yesterday and this morning there was no rattle....If others have experienced the same issue then I'm not as worried. if it gets worse I'll have to look into it more. Thanks for the info.

Can we thus assume that the problem only exists when the car has been sitting a week, otherwise starts quietly on cold starts in the morning when you have been driving it daily? Moreover, is it a rattle or more of a high-pitched metallic grinding sound. If it's the latter, it sounds like the valve lifters to me. Could just be because all the oil has had enough time to slowly draw out of the chamber.

Just wanted to bring this thread back from the dead to chime in - mine does this also. Every morning on cold start up I hear it, but nothing when starting warm. I guess it's normal. Certainly sounds like pistons grinding across raw cylinders for half a second until the oil gets up in there. I guess it can handle it...

Thanks for the info, I assumed that it was the lifters. I just wanted to know if it was common. And it seems that there are a few that have the same issue. So either we are up the creek with a problem or we are ok.....I'll have to check later down the road and see if you guys are asking about engine replacements, then I'll worry.

No noise in either Porsche even after sitting 3 - 4 weeks in this nice mild Chicago weather. However, I do not run 0W40 in them. So if it is normal, there must be something wrong with mine.

Eharrison, mine does the same after oil has had a chance to drain down from the heads. My favorite mechanic at the local Porsche dealership heard it when they had the car for several days. He said it is very common as the oil drains away from the valvetrain. He assured me that it is not a problem.

Mfletch, you have a vesuvio metallic as well, how do you like the color?

I had something very similar. It actually ended up being the driver's side cat was blown out. It was replaced under warranty and no more knock.

+1 from my Indi.....

So, I have to ask this. For those who believe the noise is from the valvetrain and is a result of oil draining away from the valvetrain within a few days, what have you done to correct the problem? Maybe try to switch oils? For those who think the noise is not a problem, think again. If the noise is a result of an abesnsc of oil, then the noise is metal parts hitting together. How is this ever NOT a problem and how does this metal to metal contact NOT cause uneccessary wear? And why would anyone accept this as not a problem just because a mechanic said it wasn't?

I fixed this by parking mine upside down. Getting in is a bitch, but no start up rattles!

I have the same noise but it def sounds like an exhaust rattle so I didnt worry about it-good to hear thats "normal"

Any suggestions to a correction? As for the oil, I'm currently running the factory spec weight for oil, would going heavier solve this? Meaning it would require more time to drain from the valves? Or would going to a lighter weight somehow correct the problem? How do these changes affect the oil pressure? What about a car that is run in hot climates, does changing the weight create new problems? I'm wondering if this is the type of issue that creates the idea of a daily driver seeming to have less issues than a garage queen. Since it is not driven daily and they rattle is creating excessive wear because it sat for a long time. Any comments?

Factory spec oil weight is anywhere from 0W40 up to and including 5W50. I assume you are running 0W40. I run 15W50 all year in Chicago, but have run 5W50. If the noise is from excessive leakdown in the valvetrain, then, yes, a heavier oil will help. In Arizona, I would run 15W50 all year too. Here is another thing you might try. This has not been proven scientifically, but it corrected the problem in a few of my buddies 996's. I have not given much thought as to why it eliminated the noise other than maybe where the oil drains from or whether it is just a coincidence. Try parking the car with the backend lower than the front. In many garages, if you pull in forward, the slope towrads the back may be enough, but many do not slope much at all or you may have taller rear tires; otherwise, pull your front tries up onto 2 X 8's. In three cases, when we did this, the noise was eliminated, only to come back again when the car was parked, either level or with the front end lower than the back. Personally, I am leaning towards timing chain noise where the oil slips off the shelf and/or tensioner when at a certain angle and sitting for long periods, but I have not experienced it personally, so haven't looked into it in detail.. Kepp us posted. Like I said, it could be voodoo but ot costs nothing to try.

Thanks, I'll give it a go with the 2X8's. As for the weight, I know it's not 0W40, I pretty sure I'm running the 15W50. I'd have to check the 45K service that was done last fall. Would you use a lighter weight in a colder climate? And heavier in a hot climate, so that the viscosity runs the same? Or does a heavy weight oil reduce the capacity to transfer heat? Therefore the need to have a light weight in a hot climate?

The thicker oil will leak out of the lifters slower and stay attached to parts longer. Above around 20F, the flow of a 15W50 and a 0W40 is the same.

"Above around 20F,the flow of a 15w50 and a 0w40 is the same." I'd like to see your proof on this statement....Where did you come up with that idea? And do you realize it's false?

Under the pressure of a positive displacement pump they flow the same. I have proven it.

Wow, I'm sorry to have to tell you this but you are really wrong on this one....You cannot make something "so" just because you state it.....

Ok, so provide us with your proof that what I say is not true, or are you one of those peoiple who think that higher oil pressure automatically mean less flow? I await YOUR proof but I won't hold my breath. I won't bother responding to you anymore on this thread since we all know you just enjoy telling people they are wrong and never offer any support for your side. Very typical of someone who knows little about a subject.

The burden of proof usually lies with the person who is making a claim which is contrary to proven facts, isn't it? I have no interest in telling people they are wrong unless they are. This forum exists to help people understand and sometimes correct issues that they are experiencing with their Porsches. In my opinion,you are providing false and sometimes damaging recommendations to people who ask for help.

On the rattle discussion, I'll chime in with a 'me too'. Turned out to be a broken baffle in the exhaust, which I immediately used as an excuse to upgrade the exhaust system. My wife is amazed at how much baffles cost... On the oil discussion, FWIW, there's an interesting little piece in the current Excellence about why such light oil is recommended. I found it very persuasive. Without prejudice to fellow Rennlisters who may feel differently, it decided the question for me.

Eharrison, yours looks great. I love the color because it is a little different. But then again, I love the kermit green and vitamin C orange 911s also. When I bought the car, it was sitting dirty & neglected in a wrecking yard...I thought it was grey. I was very surprised when I had it towed home and gave it a bath. It took me a while to get used to having a purple car. Now, I can't imagine ever getting rid of it.

; ) -td

I know I know.... Mfletch have a pic of your car?

Hi, I have assumed (I hope correctly) that we are talking about "valve train" noise here. All noises first need to be carefully diagnosed of course! Some valve train noise is due to the metallurgy and actuators used in modern valve trains (and elsewhere). As long as the noise disappears within a short time (say 30seconds) it is harmless and a factor of the engine/lubricant characteristics. Late model BMW owners know all about the phenomenon! Some oils are less acoustically "absorbent" than others too. Various M1 lubricants can be noisier than certain other Brands at startup but THIS HAS NOTHING TO DO WITH ENGINE WEAR!!! It has a lot to do with the base lubricant(s), its pour point and the additive package used! Brant - you are correct the "flow" of a 15w-50 viscosity lubricant and a 0w-40 viscosity lubricant will indeed be VERY different at 20f (-7C). Well, that is if we firstly rationalise a few things; a) Is the 15w-50 lubricant a mineral or synthetic? (The 0w-40 will be a synthetic!) This would make a significant difference! b) The Brands and Models of the lubricant will tell the story! Similar specification lubricants do not always produce the same results as they warm up! c) We must assume that by using the word "flow" you mean the ability of the lubricant to arrive at its desired location in sufficient volume to do its job! This is because the oil pump's output (volume) is constant per revolution - engine oil pumps are of a constant displacement as we all know! The respective viscosity estimates of M1 at 20f (-7C) are; 15w-50 (EP) - 1292cSt 0w-40 - 530cSt This is a significant variance!!! Understanding how these two lubricants will circulate and lubricate an engine at 20f (-7C) is not too difficult. The non Approved 15w-50 lubricant is almost 2.5 times more viscous (thicker) than the Approved 0w-40! Imagine this lubricant trying to enter and leave restricted valve train components and elsewhere as the revs climb! Normally up to 25% of overall engine friction comes from the valve train area - increased viscous drag in this area can cause increased loads on cam lobes. Increased "stiffness" is certainly a design consideration as far as wear factors are concerned At 20f (-7C) the more viscous lubricant (15w-50) will likely exit significant volume via the system's by-pass. It is unlikely to be flowing through the filter's media either as it will be in some position of differential by-pass at this temperature. Some non OEM filters stay longer in by pass but normally it can occur up to and beyond an oil temperature of around >70C. Even with synthetic filtration media such as Donaldson's excellent "Synteq" this can occur until the oil's temperature is >40C or so The less viscous lubricant (0w-40 synthetic) will most likely not trigger the lubrication system's by-pass very much at this point 1999Porsche911 - as usual you appear to be a little "lost" in the realms of engine lubrication and lubricants. Both viscosity lubricants will "flow" the same from the oil pump - its just a matter of where the oil ends up!! Also, at an engine "close down" core temperature at say a 100C (212f), both lubricants will drain away at nearly the SAME flow rates! If the engine's shut down was at 20f (-7C) core temperature, the situation would simply be that the more viscous lubricant would "hang around" longer. The end result for the engine's wear rates would still be the SAME! The "oil film" left behind has very little to do with the fluid "carrier" (the lubricant) - it has a lot to do with the chemical structures within the lubricant's formulation!! The API and ACEA quality rating processes call for minimum standards in this regard to ensure a known wear rate at start up Typically the chemical barriers are all much the same in modern additive packages but you get what you pay for! The more you pay for a lubricant the more you get in general terms!! Regards

Thanks Doug for the indepth explanation. My main concern with the "rattle" was that the valves were not properly lubricated on start up and that this rattle (lasting approx. 2seconds) was creating excessive wear. I have not owned a car that has had this issue before but then again I have not had a car with an engined designed like this. Since your from a hot arid region do you recommend 0W-40? I wasn't aware that the 15W-50 was non-approved...

Hello, yes, it is a hot and arid place here - sometimes even in our Tropics region where I live on the edge of the Great Barrier Reef Either a 0w-40 or 5w-40 viscosity lubricant from the Approvals List will do well for you. There are a number of lubricants from the List that can be purchased in NA These are Approved: Quaker State Full Synthetic Euro Formula 5w-40 Havoline Ultra 5w-40 Kendal GT1 Pure Synthetic Motor Oil 5w-40 Mobil 1 0w-40 The Mobil product has the most advanced formulation but they will all do the job. Of course they are all SAE40 lubricants Sometimes valve gear noise can originate from using non OEM oil filters. it is always wise to use the OEM filter - their valving and filtering media are of first class quality I use M1 0w-40 in my MY06 Supercharged CLK Benz - it is a little noisy at startup (for about 5secs) and I often operate it in an ambient up to 110f Best wishes

(sorry for going slightly off-topic but I know this kind of thing probably interests you) Bernd Hemminger@PAG gave a presentation over the weekend showing the new Porsche oil pump with variable output. He wouldn't say but I think they will OEM it from Kolbenschmidt Pierburg?

Hi Jason, thanks for the Info. these types of oil pumps will be a really great component offering many engine durabilty advantages We can expect closed lubrication systems soon too - these will be a "Unit" with filter and possibly a centrifuge included - and maybe no facility to change the oil! Technology moves on! Thank again Jason Regards

Eharrison, if you do a search using the words "new owner with a rebuilt 996" you will see a bunch of pictures I took while restoring my car.

Mfletch, Yeah after I posted I looked around and found the thread. The first couple of pics were sore on the eyes, they gave me a shiver. But you certainly brought it back from the dead. Nice job!

Eharrison, Thanks it was a lot of fun. I'm just finishing up another project car that I brought back to life for my dad. It's an enjoyable addiction.

I get a rattle sometimes when I throw the car into reverse. It lasts a second or two, then everything is fine.