Metal on metal sound after sitting

I've daily driven my car for the past 8 years with no major issues and very little concern about the reports of intermediate shaft issues. In the spring we decided to stop daily driving the car and just use it at the track. That means it's sitting of week or two at a time and then I'll drive it for a week. The two times I've started the car after it was sitting for more than a week I've heard very distinct noise which I believe is metal on metal contact. It lasts ~1s and doesn't repeat itself as long as I'm driving it every day. I'm a little concerned that the oil is draining out of portions of the engine or the bearing (assuming the seals have failed) and these cold start ups are going to cause issues. What are your thoughts? Thanks, Shawn

It's best if you post a video of the startup (or at least a sound file) so we can actually hear it. A brief metallic contact sound on startup *MAY* be chain slap, but of course any metal on metal sound is very worrisome and should be handled with caution.

Oil drains from various places but the most common noise is some sound like a chain being dragged over a piece of heavy lumber -- the cam chain slack is not yet taken up by pressurized by engine oil chain tensioners -- followed by some obvious but short lived valve clatter that lasts until the oil refills and pressurizes the zero lash adjusters. A metal scraping noise is not a common noise at startup so I'm at a loss to offer what it might be. Arrange a test: Before you start the engine after a time of inactivity that you know will have the noise present remove the serpentine belt. Carefully note its routing and direction of travel so you can reinstall it the right way and so it rotates in the same direction as before. The idea is to see if the noise is still present. IOWs, is the noise coming from inside the engine or outside the engine? You're thinking it comes from inside the engine, and maybe it does. You are the only one that has heard the noise, but the apparent location of the noise can be deceiving. The noise could arise from an idler roller bearing, or tensioner roller bearing. If the car is equipped with a manual transmission it could be a noisy release bearing.

I'll try to record the sound when it happens again. I don't think it sounds like a chain on lumber. It's more high pitched. Honestly the first thing I thought of was the sound of a bearing without lube. Definitely not lifters or the air pump.

I'll try to make a recording if it occurs again. I hate leaving machinery idle and not running on a regular basis, and this sound isn't making me feel any differently. I don't think it sounds like a chain on lumber. The first thing that came to mind in terms of sound was a bearing without lubrication. This may just be hysteria induced by all of the bearing discussions on this board. I agree it's difficult to localize these sounds. It could be coming from another area. Tough to tell in a parking garage with concrete walls near me...and a short duration of sound.

Is it a high-pitched squeal? A failing starter can make this sound... Does the sound change in pitch, higher pitch at first and then slightly lower before it stops? Like an angry kazoo?

Are you sure its not the SAI pump? Lifters? I would do what Mac suggested first and eliminate the accessories/pulley by removing belt. Maybe unplug the SAI pump too. With all those things not operating it should be a little easier to pinpoint. If you eliminate those things, lifters, and chains,,,,,, that leaves??? If indeed its the IMSB making the noise, time to hit the panic button.

It's definitely not lifters or SAI. I've dealt with the SAI and I'm familiar with the noise. Although I've never had lifter noise on this car, I'm also familiar with it from others.

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It is somewhat high pitched, but why would a failing starter only make the noise after the car was sitting? The period of the sound is too brief to detect pitch changes. Keep the suggestions coming...

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A high pitched sound like you describe is not a common sound from inside an engine. However, it is a common sound -- when it does occur at all -- from something outside the engine. What spins immediately upon engine start? Well, besides the engine of course there's the starter as 5CHN3LL mentioned. But it is hard to take the starter out of the picture. But it is a good suggestion one to keep in mind if nothing else can be blamed. There are the belt idler roller bearings, the tensioner roller bearing, and all those accessory drives. My Turbo developed a noisy idler roller bearing but the noise was not a high pitched squeal. It is hard to describe now but the first thing that came to my mind was a "dry" bearing, not not a dry plain bearing, but a dry roller bearing. Any accessory proper can make noise. Each has at least one and probably two roller bearings. I myself heard a bad water pump from my Boxster, though admittedly the water pump did not squeal. It rumbled and not very loud either. There is the power steering pump. In short any accessory driven by the engine belt or engine directly can produce produce the noise. Now the belt itself can make a noise. I have heard a high pitched noise, best I come up with described as a chirp -- but sometimes a chirp that lasts a bit longer than a chirp, more like a chiiirp, but not long enough to become a squeal -- when starting my Turbo from cold after it has sat out in the rain or even after just a washing. Depending upon various factors: climatic conditions, age of the belt, the tensioner's, errr, well, tension, it is possible for the belt to be the source of the noise you hear. The noise doesn't have to be a rotating part either. It can be a small temporary vacuum leak. Under some AOS failure modes (or phases) the engine can be subjected to extreme low pressure. A seal (RMS is one) can leak under this low pressure and the squeal is the noise the air makes going by the seal. The AOS pleated/accordion like hose can have a small crack/split that can make the noise. A loose oil tube filler cap can leak too. There are various places the noise can come from besides the engine. I can understand the anxiety brought about by the noise. The rumbling noise I heard had me thinking serious engine trouble but a cold start with the belt removed confirmed the noise was no longer present and that narrowed the search to something outside of the engine. Frankly if it were from the engine proper I think you'd know it by now. If you want, just to be safe, remove the oil filter housing and carefully dump the oil into a clean (clean enough to drink your morning coffee from!) drain pan along with the filter element. If the noise is coming from inside the engine I think you'll see stuff in the oil/filter element. My WAG (and hope) is you won't see anything of any consequence.

If the solenoid is getting stuck, it will get stuck-er if left sitting. Mine is currently failing, but it only squawks the first time I start up after letting it sit for a day or two. You could determine if the starter is the issue by disconnecting it and then starting the car.