Rumbling noise from air con pump area - 2001 Nissan Almera Tino

if the noise is definately from the front engine timing chain cover area then the first thing i would do is remove the auxillary drive belt/fan belt then start the engine to see if noise is still there? if so the only option is to remove the front engine cover and from remember you may have to remove the cylinder heads also, even remove engine for access\,big job, the engine is normally a bullet proof unit, if the oil has been changed at service advised intervals then the hydraulic chain tensoiner etc should be ok and most noise problems at the front of engine area are caused by. ie. belt tensioner, air con compressor,pas pump etc. so if noise goes when aux belt removed look at the that area. hope this helps.

sounds like water pump or fan pulleys

you more than likely have a sciezed air con compressor. most modern cars have climate control which uses air con even when demisting and when engaged the electric clutch tries to engage but the pump itself will not turn, clutch will get red hot and burn your belts

c\heck compressor bearings before it is damaged

Try spraying some "anti-squeal" (in an aerosol from any parts supply shop) onto the serpentine belt. If the noise stops you have identified the source. Also lube the spring-loaded device that tensions the belt.

try this,when you change the engine oil and use a flushing oil before you finally fill with 10/40 semi synthetic,add stp/wynns oil additive or molyslip. the ticking is possibly a sticky cam follower(they are self adjusting with oil pressure)the water pump/air con comp cannot "tick"but they can squeel.....

So when you turn off the air con the noise stops ..
If yes then its the bearings in the Air Con pump which is driven by the same belt and when turning the r13 coolant around the bearings being dry and worn out will start to make the noise Same as the water pump does when it goes, but yours is Air Con Pump.
DONT TAKE IT OFF YOUR SELF. RON

getting good lubrication flow to the top end of the engine ? maybe some lubrication flow is being blocked to the top of the engine and you hear valve system noise.

When you think the engine is really powerful even my dads one makes that sound. I think it's the parts like airbags, handbrake area which have degraded due to Aging.

it is probally a vacume line leak or bad ac pump