How do i know if my waterpump is defective ,is there a weep hole to know if it bad.I have antifreeze leaking right behind oil pan.

Your water pump has a small hole on the top and the bottom of the housing right behind the belt pulley. This is known as a weep hole and is there to let you know when the front seal has gone out of the pump and it is in need of changing. You really want to get this taken care of because on your engine the ignition system is ran off of the crank pulley and is known as "Opti-Spark" when the system gets antifreeze in it it usually goes bad. The Opti-Spark distributor sits right underneath the water pump, so a leaking water pump soon will take out your distributor which is another added expense.

Weep hole leak usually means water pump is leaking and often due to bad bearings and seal.

Is antifreeze coming from "weep" hole in bottom of case under shaft nose?
is it coming from the heater hose (small hose coming of side and going into firewall to heater core inside engine compartment?
is it coming from bad gasket between pump and front case?

get a paper towel and dry these areas then start engine. when it starts leaking that will tell you if you need to change the water pump (gasket leak or weep hole shaftseal leak) or if you just need to replace/repair heater hose.

Take a close inspection to your waterpump. Pump has a "weep" hole in bottom side of casting. It's an early warning system to detect seal leak before waterpump seizes up and does major damage. It could be so slight that coolant is blowing back along oil pan. That would be where I'd start. Do you smell coolant inside the rig? If so, check passenger floor up to firewall for dampness in carpet - indicating heater core leak.

THAT SOUNDS CORRECT! THE WATERPUMP HAS WHAT IS CALLED A WEEP HOLE! IT IS LOCATED ON THE BOTTOM OF THE WATERPUMP! IF THAT IS LEAKING, THE WATERPUMP WILL NEED TO BE REPLACED!

check the carpet under the heater core in the interior. Check the radiator overflow bottle--sometimes they get a small crack at the bottom and weep out coolant. Check for any heater hose or other coolant hose clamp to be weeping coolant onto hot exhaust parts. The coolant will evaporate and you'll never see a puddle. The best time to check is just after engine shut down when coolant temp and pressure is highest.

Possible leak areas waterpump, heater core, intake manifold gasket, radiator or hoses. Waterpumps have what they call "weep holes" which is an early warning system to prevent major damage when pump fails. The weep hole needs to be inspected from below and is usual behind waterpump pulley. If it's your heater core, you should smell anti freeze inside truck and in most cases windshield will fog up. Radiator could be pin hole to front side of radiator (which is buried behind AC condenser & grill) and if it was head gasket, intake manifold symptoms would be coolant in oil OR lots of white smoke from exhaust. Try parking it on a clean dry surface and see if you can narrow down area where leak is coming from.

The pump does have a weep hole in it. If a seal in the pump fails coolant will come out of the weep hole. Looks like you may have a bad water pump seal, but check gaskets, intake manifold and hoses as these can leak in this area as well. So determine where the coolant is coming from before investing in a new waterpump.

This is called a weep hole and it indicates the rubber seal is now leaking antifreeze onto the waterpump bearing and it's only a matter of time before the waterpump falls change the waterpump.

you will need to replace that water lin it runs to the water pump which is why its leaking so badly....you will need to replace it asap