Grinding-like noise only on morning start-up

When I start my car up in the morning, it makes a "grinding" noise behind me that shows up a second or so after it starts and then goes away for the rest of the day. One day, it didn't make the noise in the morning but that was much later in the day. I hooked up my OBDII reader and there's no errors when it occurs. I'm beginning to think that it might be a water pump from reading other posts but wouldn't something like that consistently grind? Is it effected by how warmed up the car is?

Id suspect the WP. Easy enuf to check all pullies. Id probably do that and be prepared to put on a new belt. R&R WP is pretty easy. Just keep antifreeze mix w u so u can top off the reservoir for a few weeks afterwards.

I think if the WP bearing wears, it can cause pieces of the impeller to break off, clog passages, overheat local areas and cause expensive damage.

Try removing the accessory belt and *then* start it. If the noise is gone then it's one of a few things driven by that belt: PS pump, water pump, A/C compressor, Alternator and dog knows what else. May just be a crunchy belt idler pulley or Tensioner. If it doesn't, take a good listen to the starter... Mine would screech intermittently on cold start. Worser than that, oil pump or other engine internal.

I took it the the local independent mechanic just in case it turned out to be the water pump. The good news, it isn't the water pump (or any other accessory). After doing some digging they suspect it might be that it might be that one of the spark plugs has inched out very slightly and when the engine heats up, it causes it to shift back. They said it might be due to the spark plug not being torqued correctly. That would explain why it doesn't do it for the rest of the day and why it doesn't do it when it gets started in the middle of the day. Fingers crossed on that being the issue.

Is this on startup when stationary or only when you start moving? Brake pads will get a patina of rust if you just park it after washing, and makes a horrible grinding noise until the brake pads wear it off (usually pretty quickly). Any time you park it with wet cold rotors, actually.

Only on startup when stationary. It only occurs in the morning when it's cold and last just for a few seconds. The rest of the day is great and if I start it up in the late morning or afternoon, it's fine. Makes testing various diagnosis difficult because you're only allowed to test it once a day. The repair shop I believed mentioned that the ignition coils were cracked and that they're going to replace all 6 of them and see it that gets rid of the problem. They need to be replaced if they're cracked anyways so I don't mind if they do that.

Update: They were unable to find out what caused it. They think that something might be bleeding off oil pressure. I have the LN Engineering spin-on filter adapter that I installed at around 45K (I'm now at 82K+) and they think maybe something has come a bit loose. So the next oil change I'll remove it and re-attach it again. I asked if it was possibly the oil pump failing and they think it's unlikely. Edit: added the word 'adapter'. I've had the adapter on since around 45K

"bleeding off oil pressure". No offense to you at all but that's a bit of a howler. The only way the adapter would be impacting oil pressure is if it were leaking. You'd notice. So would your mechanic. He may be sending you in circles but it's your wallet. Slightly more likely is a blocked filter or one with a defective internal pressure relief valve... Causing the oil pump to labor on cold startup. But there's a pressure relief spring in the oil pump itself; still... Easy thing to do: change the filter only. Now. If your noise *changes* cut the oil filter open (oil filter cutter and latex gloves), unwind the filter media and look for any debris. It's unlikely but a filter containing debris is an indicator of possible seriousness. As I said, unlikely. B) pull the carpet and service cover behind the seats, detension and remove the accessory belt and start the car when cold. Noise gone or different? Look at the accessories, belt pulleys and Tensioner. In any event, I strongly suggest Wayne Dempsey's book of projects for the boxster and cayman. Step-by-step details on how to do disassembly, repair and re-assembly: https://www.amazon.com/Projects-Por.../dp/0760335540/ref=sr_1_2?ie=UTF8&qid=1476486510&sr=8-2&keywords=Wayne++Dempsey Work on your Porsche, it's freedom.

If the filter is blocked or there's a defective internal pressure relief valve, would that cause it to only show up on a cold morning at the same time and duration? Mechanically, how does that occur? It doesn't happen if I start the car in the late morning onward and doesn't show up for the rest of the day. That's why makes this problem do hard to test. You only get one shot in the morning otherwise you have to wait a day to try something else. Also, when you remove the filter, how much oil is going to come out? I imagine I'm going to have to pick up a few quart of clean oil and top it off. Like I said above, no change when they removed the accessory belt and started it up. I have been working on most all the maintenance on my own (didn't do the clutch myself). From the spark plugs, to the brakes (disc and fluids), and the accessory belt. The reason I brought it to the mechanic was because I couldn't diagnose the problem and I don't have the time to work try things in the morning (gotta head to work).

Replacing the filter shouldn't dump much oil, not like dropping the drain plug. Sorry I missed the details of your trying the car with the belt off... Your mechanic was going down the path of oil pressure so that's why I suggested the filter swap. Added some immediacy in case it *is* the problem. If it doesn't change anything, nothing lost. My hunch is the starter. Mine would squeal briefly, only at startup, cold... Not much else is driven without the accessory belt: oil pump and starter. If you've overrevved the car, consider an oil pump replacement. If the oil filter is clean then suggest you drive it until it gets worse. mmmv, -PM.

Your mechanic is either incompetent or an outright thief. First he says the spark plug is loose and that might cause the noise. Then he says the coil packs are possibly causing the noise - No they can not. He is just changing parts because you are frustrated and he sees dollar signs. On your next day off, remove the engine cover and have a friend start the car while you listen from the rear. Get in the back of the car and get in close so you can pin point the area fo the noise. Unfortuantely, the noise is temporary and you only get a few minutes. Maybe, if the noise stops, turn off the engine and let it sit for an hour to cool and try again. Intermittent problems are the worst to work on.

If it is a true grinding sound, it is possible that your oil has degraded and is allowing metal to metal contact to occur. If your oil is too thick or too old, or if the filter does not have an anti drain back valve, an oil change and filter change may be the cure. I just noticed that your filter has been on the car for 37,000 miles!

Well, I wouldn't go that far. Cracked ignition coils need to be replaced and from what I've read on these forums and other Porsche ones, it's better to replace them all at once. It's also appears to be a common issue. There have been posts about people replacing one and then getting another misfire error and having to get back in there to do the others. I'd rather not have to spend the money on labor multiple times if they can just get it done altogether. I'm always interesting in learning more about cars. Could you explain why cracked ignition coils with their internals exposed to the cold would never cause the problem I'm having? It would seem like like electrical resistance and load can be affected by temperature and that would explain why it does it only in the morning, once for a short duration (a few seconds), and never shows up again for the rest of the day. And because of this last thing I can't do what you recommend. I let the car sit for 9 hours and it still doesn't do it again until the next early morning. If I wait and start the car in the late morning, it doesn't occur. I don't think the mechanics are thieves because they're trying all the stuff that makes mechanical/electrical sense to them. And he's not just changing parts. He didn't change the spark plugs; only the ignition coils. They also tried starting it up and having multiple technicians try and locate the source of the sound (what you recommended). In the end, the shop said they're stumped and that I should try doing certain things myself (oil filter stuff). If they really wanted to rip me off, they would have said they'd do it and charge me for it. I'm curious as to what you would have done in this situation that's different than what they did.

Will it get cold enough in the winter so you can test more often? What if you start it, then shut it down right away? Will it act up when you start it again? That one test/day is a real problem, exactly as you wrote.

I changed the oil filter like Plainsman suggested and the problem was gone the next morning. It may have been a defective filter that failed. I'm going to do a complete oil change soon and send the material to Blackstone labs to see if there's any problems arising. I don't have an oil filter cutter so I can't check the contents and see if it trapped anything important but I do have a magnetic drain plug so hopefully that doesn't show anything.

I'm going to guess Fram filter? They are notorious for bad anti-drainback valves. Spin on adpater is a solution in search of a problem on these cars, IMO.

It's a Napa Gold / Wix 1042 filter. All the previous filters have been great for the last 2.5+ years. Hopefully, it was just that one filter that went bad after 2,000 miles. I bought the spin-on filter for quicker and less messy oil changes.

That's unusual as the Wix filters are usually decent. I've never noticed the canister to be much messier than the spin on filters, myself. It may be, but given that you seem to have introduced a new failure mode by using it it may not be worth any added convenience.

Regarding the screech on startup, my car (2006 Boxster ), has the same noise. This might be the fix. http://www.planet-9.com/files/downloads/3/37/20060716164324_1948_ScreechingNoiseFromEngine.pdf

Thanks for the tech document. I'll have to keep an eye on it and see if it develops again. Is this something you can do yourself if you've done something more involved like a spark plug replacement?

When I purchased my 2005 Boxster , I experienced this. The dealer did the above fix and the issue was solved. My Cayman never did this.