firstly, do you have the equipment to change the head gasket.
ie: a suitable torque wrench for the head bolts?
do you know how to re-time the engine having removed and refitted the timing belt(which you should renew)
I`mj looking at the worshop manual now and I presume you know how to strip an engine
The important part is when you replace the head (having made sure it`s not warped or cracked) and having cleaned all mating surfaces, you should have ten cylinder head bolts the tightening sequence is ____________________________
8 6 2 4 10
9 3 1 5 7
the torque settings are assuming you`rs is a M.40 engine is stage1 30 n/m stage 2: angle tighten 90 degrees stage 3 angle tighten 90 degrees.
The knock sensor responds to spark knock caused by Pre-detonation of the Air/Fuel mixture. As the flame front moves out from the spark plug ignition point, pressure waves in the chamber crash into the piston or cylinder walls resulting in a sound known as a knock or ping. This is caused by using a fuel with a low octane rating, overheating, or over advanced timing. Sometimes it can be caused by hot carbon deposits on the piston or cylinder head that raise compression. A knock sensor is comprised of Piezoelectric materials; Crystals that when impacted, generate a voltage (same idea as a BBQ ignitor). This voltage is monitored by the computer, and when an irregularity is detected, the computer corrects timing in VVT (variable valve timing) engines, or triggers a DTC Diagnostic Trouble Code) in older vehicles.
Hope this helps; also keep in mind that your feedback is important and I`ll appreciate your time and consideration if you leave some testimonial comment about this answer.