Few months ago I replaced my water pump, but the heater bypass tube was completely corroded and wouldn't come out. I went ahead and put the new water pump in and filled the system up with distilled water, but unfortunately I could only get the system about half full before it started to pour out of the the inlet hole for the bypass tube.
There was an AutoZone with the part about a mile and a half down the road, and figuring I had enough water in the system to keep it cool for a short drive went ahead and drove over.
Thermostat reached a max of 210 when we got there, but I'm not sure if it was accurately measuring temp since the system was low. While there was no smoke, steam/water started coming out of the return hose from the heater core right as I pulled into autozone.
I drove the truck for a few weeks after this and didn't seem to have any problems, (It's in storage now) but I'm still kicking myself for doing that. My guess is that the pump wasn't actually circulating any water since the system was only half full/pump was sucking air through the heater core return hole. Hopefully I'm wrong? It was a cold night out, probably high 30's, and the drive only took about 5 minutes, but I'm paranoid that I might have damaged something. What do you guys think?

5.9 v8 magnum 46re trans
Already asked this earlier but was hoping for further clarification

 

Bad idea. Pump likely was sucking air, and that doesn't cool the engine well. Is there damage done? Gonna have to do some troubleshooting to find out. Pressure test the cooling system, see what happens. Checking for combustion gases in the coolant would be wise as well. Make sure the oil isn't contaminated.

 

I agree very very bad. You could of blown your head gasket(s) ruined a part of the cooling system, or warped the heads. Do the tests HeyYou mentioned. It wasn't circulating any water.

 

Ugh, yea I don't know what I was thinking. The coolant is clear and the oil was not cream colored as of my last oil change. I'll have to pressure test the cooling system when I pick it up. Haven't felt a loss in power, seen any white smoke in the exhaust or noticed it burning oil. I'll stick a boroscope into the cylinders as well, see if I see any scoring. Any chance I got away without breaking something?

 

Anything is possible

 

Even with a drive that short? The engine was almost totally filled with coolant, it just wasn't circulating-- not to mention it was a cold night.

 

Like I said anything is possible. Got could have done no damage or could have done a lot. I personally overheated these engines plenty of times and still drive 10+ miles with no damage.

 

Last question then I'm done -- under normal conditions if you were to disconnect the return tube from the heater core, would coolant spray out? I'm still trying to gauge if the pump was circulating any water at all -- it's a pretty powerful pump so I'd think as long as the water level was reasonably high (which it was, pump was filled up to the level of the inlet hole) it would still pump water even while sucking air. But the ultimate tell is that no water came out of heater core return tube even with the heat set to full.

 

Yes coolant should come out

 

Was my temp gauge reading totally off in this situation since there was no coolant circulation?