My 2000 Blazer has been down for a few months while I waited to be able to afford a fuel pump. During that time I realize we were going to have several cold nights and being uncertain of the antifreeze situation I was concerned of freezing. Unable to start the engine with no fuel supply, I was told to drain the radiator and disconnect the lower radiator hose. I did so and a great deal of water drained out. Today I finally was able replace the fuel pump but when I added water it immediately drained from an area above the right motor mount. I am unable to see the exact problem but am wondering if I may be lucky enough to only have a freeze plug become dislodged. The motor starts and runs well with no steaming but I cannot add water. How can I check to see how bad the problem is and what are my odds on it being simply a freeze plug if this motor even has one. Thanks

EDIT: The low temperatures were only over a few days. The worst for a 6 hour period when the low was about 13 with wind factors bringing it down to 9. The next 24 hours the temperature did not get above 32. Overall it was exposed to temperatures in the 20-30 degree range for about 30 hours over 4 days. Also, is it difficult to access the plug? How can I reach it. The leak is strong, literally as fast as I can put the water in. I hope this is an indication of a plug being dislodged instead if a crack. I also should mention that I searched the area where the truck was parked and I could not find a plug.

 

The engine has freeze plugs. You could try looking at the engine over the top of the right tire and lifting the dust cover.
Will likely need to get under the engine and determine if freeze plug or block is cracked.

Good luck on this one....I do not know if a freeze plug can be replaced with the engine installed...doubt there is much room to get to it.

 

Draining the block may have saved it by leaving room for the coolant to expand. The plugs do very little, if anything, to protect against cracking the block. The holes are used to wash sand from the casting process out of the block after it cools. The voids left behind are now coolant passages. Depending on how much antifreeze was mixed in, 20 to 30 degrees may not have been cold enough to cause any damage, and the plug failure may have been coincidental.

Access is limited, to say the least. As Lanny suggested, remove the right front wheel, and starter if necessary, and that's the best access you'll get. If the plug is the problem, you can remove it using channel locks, or knock it back into the block, (won't hurt a thing). Most auto parts stores have rubber plugs with a bolt in the center. Tightening the bolt expands the rubber and seals the hole. MUCH easier than trying to drive a metal plug back in.

EDIT: Here is a "typical" plug, you will need to measure for the correct size that you need: http://shop.advanceautoparts.com/p/d...rm=freeze+plug

 

There are two frost plugs on each side. Front one is inside where the motor mount bolts on. You can see them in these photos if you look closely (second photo is a bit out of focus but it is before engine was painted and the frost plugs show up as gold color.. Would have to remove motor mount if it is the front one that is leaking, but I think even that one could be done with engine in place if the rubber expander type frost plugs are used. Not so sure about the driver's side, though! Maybe! All but the passenger side rear one are going to be pretty difficult with the engine in place!

 

Thanks for everyone's help. The problem turned out to be a freeze plug indeed. It was totally dislodged and was laying inside the motor mount. The only real problem was getting to it and removing the motor mount to re-install. In addition to the freeze plug being replaced I have also seemed to have eliminated another problem previously believed to be due to a leak in the intake manifold. The radiator has now been filled and remains so after several hundred miles. Before the freeze plug was replace I had to constantly add water. I believe the plug was not seated properly and water has been leaking around it for sometime. I guess I was lucky on this one. Thanks again for every ones opinion and help

 

Were there signs or rust/corrosion on the plug? I would think that removing the lower radiator hose would have brought the coolant level below the core plug, but maybe not????. There are brass pipe plugs, (visible in the 2nd image in post #4) below, and rearward of the forward plugs on both sides of the block. They are there for draining the block.

 

There was some corrosion on the sides of the plug. It was brass as you said and I lightly sanded the areas and applied grease before reinserting. It was a tight fit and so I am confident it will stay in place. Like you I was surprised draining the bottom hose would not have brought the water level below the plug but I have to believe it did not.