94 C1500 Silverado Chevy Overheated

I have a 94 chevy silveraro c1500 that got hot last night. I guess my son forgot to check the water. It steamed up pretty good. He didn't drive it very long, then pulled over. We stopped and had pizza and then came out and it was cooled down. I put water in it and 2 quarts of oil to get it home. It initially went up (temp) to 240 degrees but then went back down and the temp is hanging around 180 or so. I realize the lack of water or coolant (which I plan on backflushing and filling today) was most of the cause. But could the thermostat maybe be part of the problem? Any opinions on this? Suggestions? thanks

Check for coolant leaks. Commonly the lower intake gaskets leak, but sometimes they leak internally to the engine. Make sure the engine oil level is not higher that a day or two ago. Also, check the rest of the system for leaks. When was the last time you replaced the radiator cap? A weak radiator cap can make the engine over heat. If you are going to flush the system, for the minor cost, I'd put in a new thermostat and radiator cap. Then you need to check and see how it acts after. Hope this helps.

is the thermostat on top of the engine on this model? as far as the radiator cap, a friends dad put that one on and I don't like it so I will replace it. i backflushed it good today. took more than the normal 5 minutes for the water to get clear. pretty rusty. anyway, i appreciate the help. thanks

Yes, If you follow the top radiator hose to the engine it will come to the water outlet which is bolted to the engine. Under the water outlet is the thermostat. Once you remove the water outlet, place it against a metal flat surface, just to make sure it isn't warped since the engine overheated. if all is ok, make sure both surfaces are clean and use a new gasket. Hope this helps.

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I went out to check the water today. My son drove it last night. It seems to be dripping antifreeze in the center right behind the fan where I am assuming the water pump is housed. I looked up under there as much as I could and it is pretty slimmy like it had been there awhile. I wanted to point out to you that I changed the lower radiator hose going to the water pump about 2 weeks ago. I thought that was the problem but couldn't really find a hole because of the gunk. Anyway. What do you think happened to the housing? Also, if I replace it, is it a big job? hours etc???. I appreciate the help. My son is gonna have to drive my car to work today. That thing is dripping and seems like it needs water constantly for obvious reasons. thanks again for your advice.

No, the housing is only held down with 2 bolts. you have to remove the housing to replace the thermostat. I'm not trying to cause panic, just want to make sure the housing is not warped due to the extra heat that was there when the engine overheated. If it is warped, the time to find this out is when you have it off to change the thermostat. Most of them are made out of aluminum and that will warp easily. I usually just put the surface of the housing (where it fits against the engine), against a metal straight edge (ruler, builders square, etc) and shine a flashlight on one side and see if I can see light on the other. If there is any light, you probably should replace, it might leak coolant if it is not flat.

Make sure you look extra hard and use a really bright light if you can't see. The area you are talking about is most likely the water pump leaking, but just make sure the lower intake manifold gaskets aren't leaking. Sometimes they will leak and drip pretty close to where you are talking about also. I have found it possible to see the water pump "weep hole" by standing on the driver side of the engine, and looking back at an angle to the center of the engine. I will be on the bottom of the pump, but it is on an angle and should be visible. From there is usually runs down the lower hose. Hope this helps and is not confusing.

just last week I had an antifreeze leak from under the right side radiator,when I checked it out the nut that holds the oil cooling tank inside the rad was rusted away causing the tank to push back.I ended up having to change the rad and remove the oil cooler lines.Might want to check there too.

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I changed out the water pump today. I also saw where I thought the leak was coming from. I put it on with gaskets and seelant, put the belt back on.and.................. It still has a drip leak it seems like right in the middle coming from under fan area close to the engine. have i missed something. help, help, help. thanks

There are only a couple of things in the area you are describing that could leak coolant. 1) water pump/gaskets, 2) upper radiator hose, 3)lower intake gaskets, 4) heater hose. My suggestion, look really close to all the connections, make sure the hose clamps are good and tight, use a small mirror on a swivel end and a really bright flashlight. Follow the water trail up and it should tell you where it is leaking. You can remove the fan shroud and fan clutch and gain a better view of the area. Good luck.

I tried to look again at the leak, trying hard not to get the wife involved. She isn't too happy about this right now. I retightened the bolts to the water pump thinking i didn't get them tight. i wasn't able to get a good view yet. however, i noticed that there is a steady drip that is settling around the oil pan it seems like it is starting along the right front of the engine, without taking everything off i can't really tell. i understand you told me that there are only a couple things that could leak, but, when it got hot, a couple fridays ago, could it be possible that the engine cracked somewhere around there? im just throwing it out there because im not really sure. im just running out of answers. i appreciate your help. and again, thanks for the multiple responses.

terry

Typically the only way coolant could end up there would be from: 1) water pump gaskets, 2) lower intake gaskets, or 3) thermostat housing area. Assuming the engine doesn't have any cracks. If the engine has a crack somewhere it will be hard to find. In extreme cases a freeze plug, cylinder head gasket, or crack could be causing the leak. I would bet my money on a gasket leaking and not a crack. Just a thought, did you put teflon thread sealant on the water pump bolts? They go into a coolant jacket and coolant can wick up the threads of the bolt. Use the liquid teflon sealant, not the tape. The only way you are going to find it is to take as much off the engine so you can clearly see the trail of coolant. I don't know if you can purchase it at an auto parts store, but companies make a flourescent dye that goes in the cooling system, and shows up under an ultraviolet light. It would be an expensive tool to use just this once, but it is an alternative. I know it will be a lot of work, but if your leak is consistant (sounds like it is), you need to get all the stuff out of your way so you can see where it is coming from. Do you have a neighbor that has a good set of eyes? You might have frustration blindness and might need a fresh set of eyes to help out. Just a thought. Keep posting, good luck.

well, I finally figured it out and with the help from you, it does not leak. it was something so simple it makes me feel like im getting old and not catching it anymore. the intake hose was not pushed up far enough and the hose clamp was not on straight so water was seeping out and it looked like it was leaking from elsewhere. i was wondering why it was leaking more after the water pump was replaced than before. i deeply appreciate the very helpful information and thank you!!!!!!!!!!!!!!!!!!!!!!!!