How do I bleed the coolant system???

[DJorgie76]

I know this has been gone over numerous times on this board, but I have yet to se a concrete answer to the question. I have a 95 Lumina with a 3.1. I have been trying to bleed the system and can't get the bleeder valve un the thermostat housing to spit out coolant. The valve on top of the water pump had a steady flow of coolant. Another thing that is weird is that when the car's temp is in the red, the hose coming from the thermo housing is not hard at all. I mean it was at one pint and thats when the car wasn't overheating. It's like the thermostat is sticking shut, but it is new and the when the old one was in there, the car acted the same. I am very confused and I really need to get this car running again. There has to be a way to bleed the system correctly. Any hep is GREATLY APPRECIATED!!!!!!!!!

Doug

[jeffcoslacker]

I've typed the procedure so many times here it isn't even funny.

You have to let it warm up, then shut it off, wait a few minutes then open the t-stat bleeder and the cap and refill.

If there's air trapped behind the thermostat, it's being forced against it by water pump pressure. The stat can't sense the water temp, because there's no water there. So it stays shut and the engine begins to overheat.

Are you sure the bleeder isn't clogged or something? Do you see bubbles or nothing at all?

You might wanna try filling it with the whole bleeder fitting out, allowing it to purge more freely.

Other than that, you might have a wonky temp sensor.

[DJorgie76]

I know the bleeder isnt clogged because I can hear the air coming out of it. I tried it earlier today and air was coming out the thermo bleeder for a very long time. I finally gave up and posted here. So, you are saying to not run the engine while the bleeder is open?

You have to let it warm up, then shut it off, wait a few minutes then open the t-stat bleeder and the cap and refill.

Then what? Do I leave the bleeder open while running the car until coolant comes out, or close everything, run until hot and do it again?

Sorry to sound like a moron but I just want to get this done so maybe I can use this car again.

Thank you ahead of time!!!

[jeffcoslacker]

Leave it closed and let the car run. let it run 15 minutes or so, as long as it's not getting too hot. Then shut it down, let it sit and heat soak for about 8-10 minutes, then open your T bleeder, then the cap. Fill it, cap it, and take it for a drive and see what you have.

You don't think you could have a compression leak into the cooling jacket, do you? Did it get driven a lot with high temps?

[DJorgie76]

I did drive a lot with high temps. How would I know if I have compression leak into the cooling jacket? Is that another way of saying blown head gasket?

Thank you for all your replies!!

[jeffcoslacker]

Yeah, or a cracked head....it's a bit difficult to tell without really knowing what to look for.

Sometimes you get coolant/oil cross contamination, sometimes exhaust steam, sometimes no real symptoms other than higher than normal temp and endless air in the cooling system. Sometimes you get lucky and you find a spark plug with obvious signs of coolant exposure, like sometimes you'll pull 'em out and one will be wet after sitting all night, stuff like that.

It just depends on the nature and location of the break, so without a trained eye it's hard to tell.

When you start the car up see if the hoses get tight with pressure almost right away before the engine starts to warm up...that can be a sign something isn't right.

[DJorgie76]

jeffcoslacker, Thank you for all your help tonight!! I will try these things tomorrow morning. I am not a total idiot when it comes to working on cars, but I am not a profesional either. I think I can handle the things you told me about tonight.

I will post back to let you know what happened. Thanks again!!

Doug

[jeffcoslacker]

One more thing...does your radiator primary fan cycle on when it begins to show hot?

[DJorgie76]

When it starts getting hot, one of the fans will turn on. If it continues to get hot, the other will turn on too.

[jeffcoslacker]

OK good, that means the fan circuit and sensor is good, and the ECM sees the temperature situation.

I wondered if yours might just be a bad sensor for the gauge, but if it kicks the secondary fan on, and they don't ever shut off, it would seem it is truly getting hot....the ECM uses a different sensor than the gauge to decide when to run the fans....

[DJorgie76]

Well, I did what you said and it seemed to work better. But, I noticed when the car is idling, it runs a little rough. Kind of like one spark plug wire is off. Also, when I took for a 20-25 min drive, after bleeding, at stops I could smell a faint smell of coolant in the exhaust. It has that sweet smell that stings your nose a little. Also, towards the end of the ride, the temp was starting to get higher and higher. The temp would come down, but it was getting before coming down. I mentioned I had a car in the passed that blew a head gasket and it did the exact same things as this. My previos car would blow all of the coolant out with the exhaust very fast but this doesnt. I guess I have a blown head gasket. That sucks!! Oh well. Any other suggestions would be, again and always, greatly appreciated!!

Thanks,
Doug

[richtazz]

There is a test kit that will show if you have combustion gasses in the cooling system. I found it at Harbor Freight for about $30, or you could try an Auto Value chain store (I've seen the same kit for a few bucks more in their tool sale flyer). Essentially, the kit consists of a liquid chemical that you pour into a tube that sets on the radiator cap opening of the radiator. If the liquid changes color, you have combustion gasses in the cooling system indicating a head gasket leak. The other problem you may be having is the intake gaskets. What original issue led to needing to bleed the cooling system?

[DJorgie76]

What original issue led to needing to bleed the cooling system?

The car just overheated one day and was low on coolant. I found that the coolant was never replaced or flushed at all in the 10 years my grandfather owned the car. I flushed it and put all new coolant in. Same problem. Then I replaced the water pump, thermostat, temp sending unit(not sure if thats the correct name), and had the radiator flushed. It worked for a little after that, but then started overheating again. When it over heats it gets very hot then, as if something breaks free, just cools down. It keeps doing that until it just gets hot and stays hot. I think I will go look for this test kit today. I dont want to take the heads off if I dont have to. Thanks!!