Sorry I gave no explanation here... the video ^^^above^^^ is of about 20 minutes of watching the car warm up while filling the cooling system, after the car sat cold all night.

The video itself is compressed to about 6 minutes... popcorn anyone?

 

Wait, it puked all the coolant to the overflow? I had that happen on my 1990 3.1 V6 Z24. It ended up with a crack in a cylinder. However those engines were bad about cracking blocks(from what the Chevy dealership told me).

If your radiator cap is fine, then I think you need to be concerned about a head gasket issue. Especially, after overheating it.

 

I haven't finished watching all the video, but I would not open the bleed screws with the engine running. That can actually cause the engine to suck air into the system. I know that is contrary to what many people say on this board, but I have seen it happen. The best way to handle the LT1 cooling system is how the factory manual states.

With a cold engine....

1. Fill the overflow to the hot level.
2. Fill the system with both bleed screws open until coolant comes steady out both. Close them and don't mess with them anymore(unless the engine is off).
3. Fill the radiator 3/4 full.
4. With the cap off the radiator, fire up the engine.
5. When it gets to temp, the thermo will open and then you can top off the radiator and put the cap on it.
6. From this point you can drive it for a few miles, then park it and let it cool down completely.
7. Once cool, check the overflow level(fill it to cold level). Under normal circumstances, the radiator should be full. I can't think of a time using the above when the radiator needed topping off. I generally do have to add to the overflow(that is where the system is filling itself upon cooling down). However check the radiator level still the same. It should be full. If not, top it off, heat cycle the engine to temp, shut it down, cool it off, then check again. It shouldn't take more than 2 or 3 trips to get it right. Usually it's only 1 or 2 in my experience.

I have done the above for years with zero air problems from my LT1. You must careful though...if you fill the radiator too much, the damn thing will run over like a volcano until the thermo opens....then the coolant level in the radiator will drop like a rock when the thermo opens. I got tired of cleaning up coolant waiting for the thermo to open.....so I bought this.....

Lisle Spill Free Funnel


Just remember, don't let the coolant get to 210*with the cap off....it will boil. Ask me how I know(and it wasn't from science class).

With the above, you can rev and blip the throttle to help dislodge air in the system. You can also squeeze the hoses with it too(be careful when hot!). But again, I have not had to do that with the above process.

 

*puts hands over ears and goes "La La La La La I can't hear you!" really loud...*

 

Great video for sure. How did the flow actually look inside the radiator when the stat opened? Should be a pretty good flow with lots of volume? Did you try the heater again by any chance?

 

LoL, we posted about the same time. Be sure you read my post above.

 

Yup I saw that too, and then I read it twice, and it made me really sad. So now I'm going back into denial!

 

LOL, the process for filling the cooling system made you sad(post #33)?

 

How is it again that air can be sucked in when the system is under pressure?

Anyway, I always fill mine with the bleed screws open and never have any trouble.

 

If I'm not mistaken, I think it happens when the cap is off the radiator(can't remember if the engine was hot or cold). The thing makes you think it's "bleeding" air, but it is sucking it. It's been 7 or 8 years since I last opened the bleed screws while the engine is running. I stopped screwing with the bleed screws with the engine running once I saw that. I'd have to try and replicate the conditions that caused it. Can't quite remember how it happened, but it did happen. Also, the factory manual does not state to open the bleed screws with the engine running. I think the chance of sucking air is the reason why.

After I saw that, read and followed the factory manual to the letter. I've never had any problems.

 

Obviously, you can't pressure bleed the system if the cap is off. You open the bleeders while filling, then close everything back up. Once the system is up to pressure (thermostat open), you can additionally purge any air by the bleeders (if needed).

 

Sheesh I suck at this, yes I forgot to add that the heater is now working fine. Can't really explain why it didn't, now does, but fwiw it's working now (and in the above video).

I'm not completely sure what I should see that indicates 'good' or 'bad' flow... In the olden days, you could see the coolant gushing through the cores... but those radiators had the inlets/outlets at the extreme top/bottom of the radiator. With the hose locations on this radiator, I'm not sure what I should see? The fluid level rises and drops quickly, which I'm assuming indicates adequate flow?

 

That must have been how it happened(with the cap off). It's been so long I can't remember. Once I saw that, I got to thinking on why the factory manual never stated to open them with the engine on. From that point, I just followed the factory manual and let it self purge by varying engine rpms on my initial drive after filling it up via the process I listed.

 

Well..if you are ever near Raleigh...I have two lt1s at home. Would be more than glad to run one of mine and let you compare.

 

You don't have a 'spare' laying around you want to get rid of cheap do you??? I'm thinking if I have to tear it down to the block I may as well do some upgrading...