# Marbles in the engine?



## 91yrsold (Apr 26, 2007)

Hello all,
I tried doing some searching for this issue but couldn't find anything. It seems to sound like there are marbles in the engine when it is accelerating, especially under heavy load like when the A/C is on. This problem really only occurs when the oil starts to get a little old and also more so on hot days, of which we've had many this summer. It also only occurs in specific points in the rev band, when in low rev or high rev there isn't anything to speak of. Only in mid-range revs will the engine make the noise and then once it shifts nothing until mid-range again. I'm quite concerned as I believe it has something to do with the valves and/or cylinder head in general. I did switch it to Royal Purple oil a few months ago, but I also ran some Marvel Mystery Oil through it for about 500 miles before I did the switch. I use Lucas FI cleaner quite often. 
Thanks


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## 91yrsold (Apr 26, 2007)

Forgot some important items in there, my apologies:
1. 2000 Nissan Maxima SE which means VQ30DE
2. 193,000 Miles on it, Daily driven
3. Auto Trans, don't know if that makes a difference or not
4. Not sure if timing chain ever replaced, I believe it was done once but I received no service record with vehicle.


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