Car overheating, have changed EVERYTHING!
 

Well my daughters 3.4L Alero overheated. It kept losing coolant out the overflow tube. I figured it was bubbling out because of a bad head gasket. The heads were really warped, so I decided to get another engine from a salvage yard. I checked compression on the "new" engine and all were between 130 and 150. Oil was clean etc. So I installed it. When running it, it gets hot. Ironically, all the coolant comes out of the overflow tube again. Since it was showing the same signs as it did with the previous engine, I assumed it had to be something in the cooling system. I replaced the reservoir and cap as many suggest. I replaced thermostat, water pump, and radiator. It's still doing the same thing. It gets really hot and pushes coolant out of the tube. I have "burped" it after every refill to no avail. Any suggestions as to what the problem is? Could I have gotten engine with a blown head gasket? (car was wrecked with 70k miles, so assumed that was the reason in salvage yard). If it was a head gasket and "blowing" out through exhaust side (to cause bubbling in water) wouldn't I lose compression? LIMG maybe? I'm at a loss. Any suggestions would be greatly appreciated.

Hm.....could be another bad HG on that one but did you bleed the system with the little 7mm bolt on the heater tube? Or did you just bleed it by leaving the reservoir cap off? Is there no heat coming out of the vents? When i had my 3400 the HG went around 90k....LIMG around 65k.

130-150 sounds low for a 3400. If it isn't boiling in the block from air pockets, it is probably a bad head gasket on that engine as well. Was it out of a van by chance? Those tend to blow the rear head gaskets more commonly than the cars do. You have already replaced everything else that it could be from what I see.

Get a coolant pressure tester and see if the cooling system holds.

get a block tester (about 60 bucks) and test your coolant system for exhaust gases. at this point that kind of money might be worth saving the heatache.

Sorry Billy, I should have mentioned that. Yes, I bled it via the brass fitting on the tube.

WhiteV6: Now, it was out of a 99 Alero. Hot air wasn't flowing out of the vents, but I backflushed the heater core, and now nice and warm. Wow, if it's another head gasket, I'm going to cry. Is there any way to verify short of tearing the whole darn thing apart if all the cylinders have compression, there is no "milk" in the oil, and no smoke blows out the tail pipe. And do you think it's just coincidental that it's behaving exactly the way the previous engine was?

Well that's part of the problem....everytime I run the car, I have to add more water (yes I'm only using water at this point as it would be way too expensive to use coolant seeing it pushes it out every time I run it). Would it running for just a short time and losing most of the liquid be ok to test even though I would have just added the water?

Maybe a dumb question here but have you check the reservoir cap...mine was the last piece of the puzzle for my coolant problems?

Not a dumb question. Seems to be the source of a lot of overheating issues on these cars; however, the reservoir and cap are new.

I'd say there is still air in the system or head gasket.

unfortunately, it's probably the head gasket

milky oil/coolant is not visible most of the time. none of my head gasket issues have I ever encountered milky oil or coolant until it was taken apart.

smoke out the tailpipe is also not apparent unless it's severely blown.

also, water boils at 212° F, so regardless if there was a problem or not, it might still blow water out the reservoir and inefficiently cool the engine leading to warpage and more failure anyway due to boiling

Ugh :cry: So would the suggestion be to tear it all down then? Just so frustrating that I'm back at square one after replacing the entire engine and so many other components.

one way to check is to pull the spark plugs and observe whether they are wet (or if you can see coolant inside when you shine a light down there)

we used blue devil head gasket repair in my dad's 1998 chevrolet astro with a blown head gasket. we were going to need to replace the engine anyway because its so high mileage so we gave it a shot. the stuff worked like a charm. maybe you should give it a shot?

Had the exact same problem as you, yes its the HG mine blew 3 times in the front and then blew my intake mani gasket for the 2nd time so aleros now parked.

^ you shouldnt be going through gaskets that quick....

if coolant in the system is boiling at 212 then there is a problem. coolant under pressure (water or mix) will not boil till a higher temp.

with a COLD engine, if you remove the coolant cap and run the engine does coolant come out or atleast a tone of bubbles coming into the tank?

woops, yeah, the boiling point raises to 250 °F @ 15 psi
¯\(ツ)/¯

With the cap off, at idle, I don't really notice any bubbles....however, if I raise the rpm to around 3k, it starts to bubble out.

I pulled all the plugs when I did a compression check and none had signs of wetness; nor fouling....all looked good.

is that with the engine cold before it gets a chance to warm up?