How to replace a bypass nipple on the water pump housing

need to bleed the air out of the cooling system. possibly what the nipple was for.

at first i just bypass the heater core assem. go from the thermm. housing to the head nipple. if you put your heat setting to hi setting all your coolant will pour out that nipple with no hose. if you drive like that BOOM! engene blows the heater hose assembly replacement for that is $90+tax and thats bs. ireplaced mine with 2 tees it works great! it runs cooler than it ever has and the heater works when you need it. that assembley has a thermal crossover valve in it and i find no reason for it other than the heater may work a couple min. sooner.And or the coolant that ain't worth $90bucks+tax to me.i can wait a couple min, longer for the heater to work i used the tees to maintain water flow through the head nipple back to the rad,when heater is not in use. incase that was the purpous of the thermal valve crossover. i could find no one who could tell me its intened purpous at any parts store or even the GM dealership.

I have bought these nipples before from parts store. The threads are 3/8 pipe if i remember . may try finding something at a hardware store.

I have a perminent better solution to this problem. The broken part is out there however, its on "back order". The fix that I have done is to remove the water pump and "punch" out the broken piece from above. Then use a 3/8" pipe thread tap and put threads in that hole. Go to your nearest auto parts house and purchase a "heater hose nipple". Then, with a deep well socket and a long extention, thread the nipple in. Install the hose and clamp it at both ends. You can tap that hole because its cast aluminum.

You have to remove the tensioner assembly, not just the tensioner pulley, but the whole assembly, in order to access the plastic bypass hose.
Be very careful, as these pipes get old, the plastic becomes brittle, and possibly the flange end will break off and remain in the block when you remove the pipe, check the block opening carefully to remove all of the remaining flange.
Also, be very careful when removing the lover pipe nipple into the engine block, if you try to pry the tensioner assembly off the block, you will probably snap off the machined nipple that locates into the block, Ask me how I know!!! Good Luck, it can be done but you need to move carefully and deliberately. (by the way, a rebuilt tensioner assembly costs about $80 US, the pipe is about $6. New tensioner assembly comes with the pipe)

Unfortunately the heater core must be replaced because the nipple is soldered to the heater core and access to the core for resoldering is not possible unless the heater core is remove and so if you go to that kind of trouble you should just replace the core with a new one rather than doing the repair and risking a future leak after reinstalling.

PUMP MUST BE REPLACED if ANY Part of it is BROKE, as this can Lead to MORE cracks, and Ending in Catistrofic Failure.

You need to disconnect the two heater hoses going into the heater core. These hoses will go from the thermostat housing or the water pump to the firewall of the vehicle. You can just disconnect the two hoses from the firewall connection and place a nipple in between the two hoses using good hose clamps to connect the two hoses. That is all you need to do to bypass the heater. Good luck.

1. Clean gasket mating surfaces.
2. Using a new gasket, install water pump to engine as follows: Guide water pump nipple into bypass hose as pump is being installed. Install water pump bolts Tighten water pump mounting bolts to 40 N·m (30 ft. lbs.) torque.
3. Position bypass hose clamp to bypass hose.
4. Spin water pump to be sure that pump impeller does not rub against timing chain case/cover.
5. Install a new O-ring to the heater hose coolant return tube Coat the new O-ring with antifreeze before installation.
6. Install coolant return tube and its mounting bolt to engine Be sure the slot in tube bracket is bottomed to mounting bolt. This will properly position return tube.
7. Connect radiator lower hose to water pump.
8. Connect heater hose and hose clamp to coolant return tube.

does it leak not running and at outside tempature or when its running and warmed up?