Blown headgasket with no overheating?????

[bass527]

Hello, let me start withe a thank you in advance. Here is my issue. 02 sentra, one day wife drives and she came home with no oil in the car and a slight click.And the ses light is on.... I pulled the code and it was "timing advanced" i cleared it,put new oil in and click went away.This car does not leak oil on the ground ever.So where did it go? Sooo Then i notice antifreeze was low so i topped it off. Then drove a while and it seemed ok.Then the antifreeze was low again and again..then it hesitates to start but then runs ok. This goes on a few more days and then one day it was very hard to start and idled like crap, so took it around the block and hear a fairly loud clicking/tapping from the upper left area of the engine. So i parked it and left it running, and took alook under the hood. No clicking when idling, only while accelerating. So i pull the throttle to hear the click but it doesnt click, i shut the car off and notice water under the tail pipe........thats where im at. So this car never smoked and never overheated. two big signs of a head gasket.Right? So im pretty sure it is blown but what worries me is the clicking...Its in the upper area of the motor so im hoping its not the pistons...What is the clicking??cam?valve?Will it be visible if I remove the valve cover?I thank you again for your help..

[PapaSmurf2k3]

Is the oil mixing with the coolant and/or vice versa? Is the exhaust white and smell like coolant? How much oil/coolant are you going through?
I want to say this was a fairly common problem when the cars were somewhat new, but the "infant mortality rate" should have passed by now...