2003 Volvo S40 making a tap. tap, tap, silent (repeated continually) while the engine is running. Noise appears to be coming from the top of the engine. Engine has been recently preplaced but the tap continues. Any ideas?

you have to understand a service engine soon indicator is letting you know the engine is not running at peak performance and creating unexceptable amounts of emmisions. your engine runs peak at 14-7-1, 14 part air.7 part fuel, 1 combustion stroke, any different it triggers the lite. If your tapping is engine related ,say valve clearence valve.does not seat properly you lose compression on the stroke,improper burn thus the light... in short find the source of the tap and fix

sensor wire may be shorting out.sensor wire may be stripped and grounding against engine or other ground source.

Open the oil filler lid and see if the noise goes away - or lift the oil dip stick. It could be a gummed up PCV system that causes pressure in the crank case that "whistles" when the engine is running.

By opening the lid or dip stick, you're letting the pressure out and the whistling should stop.

If this is the issue, FCP Euro has a PCV replacement kit for about $350.

Sounds like your dealer is feeling its way. which sensor did they say they changed and why. Do not pay for this ****, you took it to the dealer with a warning light and they say they changed something in order to attempt to cure the warning but they failed. About as much use as changing the seat covers and emptying the ash trays! When you say noise, is this a squeal, a crunch, is it continuous or is it during change gear. Does the car slip when in gear, is there vibration. Check your engine oil and transmission oil levels

Hi,you should change cambelt pully(there is a bearing inside pully before it worn out completely,it will cause high friction and heat to burn out your bell and rattling noise).buy cambelt pully from the dealer then take it to the garage ask them to put it in for you (labor about 30.00 dollars)...the rest is ok to wait until 150.000 miles.
good luck!!!!!!!!!!!

unhook possitive post on battery....wait and then reconnect...this usually works...make sure fuel cap is always tight and never leave car running while refueling. this causes 85% of engine lights coming on

Variable Valve Timing

Its really easy... open the hood... looking back toward the car, its at the front of the engine, left hand side near the top... you'll see the hose coming out.. its held in with 2 large torx screws... make sure you change the rubber seal around the thermostat when you remove it.. also be aware some antifreeze will leak out.. so take proper precautions.. don't do it when the car's hot.. difficulty 1/10.. easier than an oil change.

volvo s80 y reg 2.4 runs ok little bit lumpy tickoover when warm but very loud whistling noise take dipstick it stops but very big suction from tube not pressure it is not breather box under manifold

check your mass meter and air filter