Hello, all. I'm changing the coolant on my '98 T100. My service manual shows 2 drain plugs, one on the radiator and one pointing somewhere on the engine (the graphic is bad). I don't see the 2nd. I drained the radiator at the bottom with the cap off, but it was still dripping after an hour. I shut it off and proceeded to fill with a flush, but it wouldn't take nearly as much water as came out, so there must be quite a bit of air in the system. I ran the engine for about 8-10 minutes at idle hoping that the thermostat would open and flush the air up, but I shut the engine off when the system never started circulating, thinking that there may be a bubble around the thermostat.

So, two questions:

1. can someone point out the 2nd drain plug to me?
2. can someone let me know how to bleed the system?

thanks

Engine block drain plug. Should be on the passenger side, on the engine block.

To do a good flush, you need to first drain the radiator, then open up the block drain plug, and close the radiator drain. Set climate controls to HOT. Get a garden hose and stick it in the radiator neck. Flush water down the radiator and it should start pouring out of the block. Keep flushing until you get good clear water coming out.

After the block is done draining, open the radiator drain back up. Let everything drain out. Reinstall block drain plug and shut off radiator drain.

Either put the front end up on jackstands, or park on a hill with the nose up higher than the rear. Slowly fill the radiator up until its full. It may burp a few times. Leave a LITTLE bit of room in the radiator, dont overflow it. Start the truck up. LEAVE THE RADIATOR CAP OFF. Stand there next to the radiator with the cap in hand, ready to reinstall the cap if it starts to overflow. If you have any air pockets, it will bubble up out of the radiator. Let the truck get up to normal operating temp (gauge a little below halfway) Top off the coolant if it gets low. Look for coolant flowing through the radiator once the thermostat opens up. After this happens, you can install the radiator cap, and you should be good to go. If the thermostat never opens, try replacing it. You could still have some air though.

found the plug. next to the motor mount near the front of the exhaust manifold. 14mm brass bolt.

Thanks for the help. As far as tap water goes, it'd be nice to flush with my water hose, but I don't want the minerals in the system. I'm just flushing it a couple of times & filling with distilled water & red.

Unless you have exceptionally hard water, I wouldn't worry about the mineral content. Your just flushing it through the way AdamF described, not letting it stew. Plus if your water runs through the house filter, it's the same stuff you'll get out of the sink. I usually would forget to switch my home filter over to "bypass" when I used the hose for anything. I would go with your plan to refill it with distilled water when you do the mix.