I was prepping my truck to take it to a mechanic that has experience with ADs. He is going to adjust the timing and valves for me (I know my limitations). So today I decided to fill up all the fluids (oil and antifreeze). When I got to about 1 1/2 gallons of antifreeze I hit a speed bump. Fluid was leaking just below the water pump. I drained the system, took off the radiator and found a small hole just below the water pump. I hope this is not as bad as it looks... I am hoping this is just another freeze plug. I replaced two on the side, but did not notice this one until now. Whatever it is, it is very thin. Is this a freeze plug? Does NAPA carry them or does anyone know a source? I would think they would be a standard item based on the diameter? If not, I need to tell my mechanic it will be a while longer. HELP!!! Greg
Hmmmmm~ Looks like a bullet hole. Must'a' been a GMC owner that saw that Chevy block setting there all nice and pretty... _OR_ I wish I knew what to tell you, but Nate and others will. I will say that is one nice job you've done on your ride, and it's a darn shame you need to deal with this. The GOOD news is, I'm sure it's something simple and cheap to fix! Good luck!
Hey Greg, refresh our collective memories here. Is that a 216 or 235? It is definitively not a freeze plug. BTW, did you know that you also have a hidden freeze plug in the back of the block conveniently covered by the bellhousing? Poor engineering if you ask me. If you had asked me what that was back in '72, I could have told you what it was and probably rattled off the part number too. A mind is such a terrible thing. Sorry I couldn't answer what it is, but at least you know what it isn't. Nate or Evan, to list a few will chime in and shed a little more light on the subject. The truck is looking good man! Ken
It is a 216 and it is a freeze or expansion plug. I knocked it out a hour ago. It is a little thicker than the side ones and it's an "outtie" not an "innie" like the side ones. It was just jamb-fit. It is 2" in diameter. I think I have found one at NAPA, but won't know for sure until I pick it up tomorrow. I read some earlier posts on flushing the block out. Since the water pump is off and the plug is out, I was thinking of doing this. Can I just hook up hose to the thermostat hose fitting and flush it out? Should I add a little Lime-Away to the water? I am in the Texas Hill Country and my water is hard enough to break your teeth. Greg
A coat hanger is your best friend! If you're going to do a major flush, get a good coat hanger and poke and prod all water jacket holes and run fresh water thru the engine until it runs clear! Then get some Dupont No. 7 radiator flush and pressure back wash it. This is ol school technology but is guaranteed to work. You'd be surprised at the amount of gunk you'll remove by using a simple piece of wireand a simple 2 part flush! Super Wally world still carries Dupont radiator flush!
flushing i believe Nate had a post on here before about using some concoction of citric acid powder mixed with water and running the engine with it to break loosen all those hard deposits.
I was reading on another post that you should remove the thermostat from its housing before doing this flush. I assume that is to avoid clogging the thermostat up with the "gunk and chunks"? Greg
Cooling System Fun (or not) Didja find the plug yet ? a brass one is best . The Citric Acid cooling system cleaning is <magic> , I just mixed up a batch for my newest old klunker last night and drove it 'round , it's out in the lot right now soaking , I leave it in a few days to ensure 100 % cleanlieness . you'll be flabergasted at both the crud that comes out and the clean bare metal that's the result of this if you take the time to do it right . The coat hanger in the open hole is a *very* good idea too , don't forget to remove the block drain plug and fish it in there too . You do NOT remove the thermostat when flushing as the heat it creates helps the cleaning do better .
Thanks Nate. Yes, I did find a plug (steel not brass). No brass available on short notice. It took me most of the day to get the D*$M thing in. I ended up having to relieve the edge with a Dremel stone, so it would go in straight. I assume this flush is done with the engine running and the cooling system closed? When the plug was out, I used a passage brush to get to the back of the water jacket and flushed it out with a garden hose. Once the engine is running, I will flush it and get rid of the tap water. Thanks again. Greg
Gerald, Helotes is NW of San Antonio in the Hill Country. I am not really in Helotes. I live in the country 10 miles NW of Helotes. Greg
Cooling System Cleaning Yes , you do it with the engine running , I did it yesterday to my newset klunker and now even the plastic surge tank (" puke tank ") is whistale clean , it has been coated inside with reddish crud , looked like paint but it's all as clean as a whistle now ~ NO commercial cleaner will do as good a job a the Citric Acid and best of all , it won't damage the aluminum parts in that old beat up Honda you have sitting either.... Flush , flush some more them flush it yet again until you can drive it 30 minutes (minimum) and still have perfectly clear water , then it's ready to be drained and re-filled with the coolant . I hate inverse welch plugs , the doo indeed need a bevel on the lip to get them in .
