I have a tapping noise in my 2000 northstar engine ? Any suggesti

For a Northstar engine there should be two - the main drive belt and the water pump drive belt.

Gm is known for the security/antitheft system failing. When this happens the car won't recognize the key and will refuse to start the vehicle, normally accompanied by a light on the dash that says security or antitheft.

http://vatspasslockpasskeysecurityhelp.yolasite.com/

You should have the computer checked for trouble codes next.

Go to www.Dayco.com, go through the menu, your cars year, make, model, engine size. there on the last page look for a link to "Routing" this is a diagram of how the belt runs on your car. Hope this helps fixYa up.

Hello: All Cadillac Devilles had a Northstar starting in 1996. It will not make any difference if it is a SLS (275 HP) or a STS (300 HP)

it is located on the fuel rail on most vehicles and can be identified by the vacuum line running to it .

Assuming its a Northstar engine--under the intake manifold --cant be seen until disassembly

take the outlet hose off from the end not connected to the pump and stick it in a small clear container which allows you to see the fluid when you have someone run the engine for a few seconds. if no fluid pump is bad. if fluid runs pump is working. reconnect and remove return this time but disconnect it from the pump. cover hole at pump to catch fluid, and submerge hose in container. run engine briefly. if fluid runs than pump is good and your problem is your rack n pinion. also check the two hoses for defects.

chech coil wires to be shure that they were pluged back in well, check ground strap,check fuel pump pressure at fitting on fuel rail

Sounds like your thermostat may be stuck open. You will be able to look at it and tell upon removal.