Pinging noise on my 1992 m42 bmw when i start the car

Over torqued and you run the risk of a stripped thread or broken head bolt. Under torqued and the compression gas will leak past the head gasket and burn it out.

No way it can

The M42 and M46 engines have the twin vanos pulleys and require locking tools to lock the crank and cam shafts inot the correct position. There are no timing marks on these as they are floating pulleys- ie they have no key locating the pulley in a specific position on the cam. Unless you make accurate marks during stripping there is very little chance you will be able to get the cam timing right on this engine without the cam locking tool kit.

You must use a special tool which bolts onto the cylinder head. It is designed to hold the camshafts in the proper position. It goes over the flats on the camshafts to hold the camshafts in the correct position. This tool can be rented. Look on EBay or check with your local Snap On Tools, Mac Tools, or Matco Tools dealers to rent one. See the link below for photos of properly aligned timing marks for your engine.

1994 BMW M42 timing chain alignment marks Google Search

is it manual or automatic

Try this. Burn off your current take of gas, get it down to a quarter tank or so. Fill up with premium gas. If the noise goes away it is probaly a condition known as ping. Which is the predestination of the air fuel mixture in the combustion chamber. This can be caused by carbon buildup and could be resolved with an upper intake and valve cleaning. If the noise persists it is most likely a mechanical engine noise, an experienced ear will be able to tell you what the noise is.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

the m42 oil pump is located inside the timing chain cover and is an integral part of the casing so it is neccessary to remove the water pump + viscous fan etc to expose the pump front cover then remove 4 machine screws to examine the pump rotors underneath.

You may need bearings in the alternator but i would first try tightening the belt,if that cures the problem you are done.If it does not and a grinding noise starts,then put bearings in the alternator.

I'd say knock sensor, especially if your getting "pinging" noise when accelerating.

could be the oil pump. Had the same problem w/ E 30. Installed a pressure gauge and check performance at different speeds. Pressure was consistently low against specs. Change the pump . . problem gone.