Brief Knocking or Rattle on Cold Start Up on Scion xD

Problem Description and Possible Solution

Some engines may experience a brief knocking or rattle on cold start up. Our technicians tell us replacing the camshaft timing gear assembly with upgraded parts will generally correct this concern.

Problem Data
RepairPal Verified
Average mileage: 68,538 (37,000–122,000)
2 model years affected: 2008, 2009
17 people reported this problem
Viewing 1 - 8 of 8 comments
It was a little cool and damp the morning it made the slight knocking noise when I first started it about 6:30 am. I live in Central Florida and cool here is 50 to 60 degrees. It was the only time I heard it, and never heard it again. It sounded as if the lifters had no oil in them and it only lasted about a second. Never happened again. I use Mobil 1 5w-20 Extended Performance 15,000 mile Advance Full Synthetic. and their best oil filter.
I bought this car used with 32000 on it. The first problen was a vibration at about 3K rpm during shifting from 2nd to 3rd gear. This was corrected by the dealer by repacing the water pump under warrenty. My next problem is a dry start that is more pronouced when car is parked in nose down position. In fact if car is in nose up position codition is fixed. This dry start is the same knocking that you hear after an oil change. Is it possible that the fix is covered on my remaining powertrain warrenty. This is a follow on report to this problem, I started using 93 octane gas and wouldn,t you know the knocking has stopped. my mechanic told me this can only be caused my preingition causing what is called piston rattle. this is the only way the higher octane gas can make a differance.
2008 Scion XD 100,000 miles

I started hearing the short grinding or nocking sound a couple of weeks ago. I can only get it at cold startup. the rest of the day, it starts normally. very hard to diagnose. I also use the mobile 1 oil. I use the 0w20 starting two oil changes ago. I have used the Valvoline full synthetic 0w 20 or 5w 20 the before.(full synthetic helps drown out most of the valve noise you get with this engine). I changed my oil, mobile 1 again, yesterday (only at 2300 miles since last change) and the sound was still there when I went to start it this morning.
if there is any solutions, I would be happy to know.
Same problem. Brief rattle/grinding sound on cold start. Has been going on intermittently for last 2 years. Started at about 20K miles but live in Florida so issues is almost non existant 5 months out of the year but progressivly getting worse. At the dealer today. Could not find anything when my daughter mentioned it on a routine service a couple years back but I have a little more information this time.