Ok, first post here but I LOVE the site have been reading everything on it for a few months now.

On to the problem, I took my car out for a cruise this morning and everything was running great, temp was right at the first mark 185? until I got home and shut her down. I was putting the t-tops back on and heard a dripping noise and noticed coolant was overflowing from the reservoir cap. It dripped for maybe 1 minute just enough that a few paper towels cleaned up then stopped. So I was very puzzled as when I pulled in the temp was still right around 185, but I turned the key to run with out starting and it was at the second half way mark..... I let it cool down then took it for a cruse maybe 15 minutes and had the exact same symptoms as before. But if I just start the car is goes right back down to 185..... I'm not sure what is causing this but it has me puzzled.... Thanks for ALL of your help! Also, car has 98k miles.

 

My car had a stopped up radiator that let it spew out water but it ran hot at the same time to.

 

Ya, that's what has me confused.... It doesn't run hot at all when driving. And not just driving, running period I let it set at idle for 20 minutes and the gauge didn't go up until I shut it off.

 

Have you worked on the car any and let air pockets get into the system? My Ford ranger had an air pocket in the heater core and it would push water out into the resevoir and then never siphon it back into the radiator. It never run hot neither it actually was running too cold.

Try bleeding the system really good and get all the air out.

 

The only work I've done is checked the coolant yesterday night because I just bought the car and wanted to make sure it still had coolant and that it was clean. It was but all I did was remove the cap and put it back on. Do I need to bleed it after checking that?

 

Ook, I just TRIED to bleed the system to no avail..... Opened up the bleeder, turned the car on and let it run after a bit the temp was just above the first mark. I waited 15 minutes and all I got was a few sporadic bubbles and the car sitting right at that temp. So, I shut it off and immediately fluid starts spewing like a volcano....

 

You don't want the bleeder open with the car on. It just sucks in more air.

If you just bought the car and don't know much about it you may have a chance of a warped head or bad headgasket. With the car cool, take off the radiator cap and let it run. The water should circulate but not sporadically bubble and bounce. After letting it run long enough for the thermostat to open or it starts spewing out turn it off and bleed it correctly. It usually takes me the good part of two hours to bleed mine.

I just fill to the top, with the car off and let it sit and every ten or so minutes air will work it's way out with the radiator cap off, and I fill it back up. Then put the cap back on and let the car get to running temperature and TURN IT OFF. Open the bleeder screw and air should come out. Close it and repeat until only water comes out.

 

Well, the oil is clean and there is no smoke. But I suppose it could still be a bad HG. I'll try, this time to PROPERLY bleed the system lol.... Thanks for the help! Sorry I'm such an imbecile when it comes to these things.

 

Ook, I did this and added a little coolant probably what was lost between the initial overflow and the improper bleeding. Only bled very little air but maybe that was the problem. I'm going to take it for a cruise tonight and hopefully when I get home I won't be losing coolant out the top of the reservoir. Wish me luck......

Also, I talked to the previous owner and he said he had recently had the coolant flushed and filled so maybe there was some air still trapped in the system and the overflow was just getting rid of the air that was still in there?

One more thing, the cap looks like it's in rough shape so I'm going to pick up a new one tonight. Maybe that is the whole problem lowering the bp and letting coolant escape too easily.

Thanks again- Joey

 

Also keep in mind your dash gauge might be wrong, it takes the temperature from the drivers side head and are notorious for being a little off. Your car might be running hotter then it says.

Does the car have an electric water pump?

 

Nope, factory pump. I've now replaced the radiator cap, bled the system, pressure tested the system and verified the thermostat is opening. It hasn't spewed out of the reservoir again but the temp is still climbing up there once I shut the car off.

Would the pump going bad cause this? I'd think if the pump wasn't working and the car was sitting idling it would overheat but I certainly cold be wrong. I really don't know what else to do except take off the water pump and check it.

 

The factory pump is driven off the cam so when the car is off the coolant stops moving, that's why I asked. There is a possibility if your running it in hot temperatures when you shut it off the coolant is just being heated up really high wherever it stops and thus expanding it out of the overflow tank. The pump can't really go bad in terms of how much water it moves, either it spins or it doesn't.

 

Right, so I guess my pump is also good. Which leaves what? Coolant overfilled possibly? I think that's what I'm going to hope for. Maybe I'll wire up a fan switch too and turn that on for a few minutes when I shut the car down. I am in 100*+ down here soo maybe that'll help.

Thank you very much for everyones help! This is my first chevy (last car was a blown 351 fox) so I'm sure I'll have plenty more questions for you all.

 

I would have to guess that the radiator cap wasn't holding pressure.

 

If I remember right my car used to do this honestly and I think it just went away, it could possibly just be that the system is overfilled. If you're not seeing any weird lights and running any odd temperatures I don't really see what the issue is. As long as your sure it isn't hurt I'd say run it until it stops (boils over enough to be filled correctly) and call it a day.

 

Took it out for a long cruise this morning and had no overflow when I got home! The temp still rose when I shut it off but no overflow so I'm happy.

 

i wouldn't worry about the temp going up on the gauge after the engine is off. Its pretty simple once the coolant stops flowing it doesn't stop absorbing heat from the engine.

 

X1000 on that. Only thing I would say is maybe the cap is bad and only holding half the pressure. They sell them everywhere. go get one top it all off and there should be no problems. Temps always rise after the egnine is shut off and water stops flowing.

 

I did, and there has been no problems since! Thanks everyone....