sluggballz

How did GM fill the coolant systems on these cars as they were on the assembly line? I follow the service manual and it seems to take forever and a day to get the air out of the system. Are there any tricks I'm missing?

kg4fku

did you use the bleed screws?

antfarmer2

They have a flow and recovery system. I just jack it up and let it bubble out.

SJW

I use my cooling system pressure tester to push the air out of the bleeders after a refill. Works great and very quickly. Pressurize the system, crack the bleeders open, and out comes the air.

It also helps to drill a small air-bleed hole in the flange of the thermostat so that it won't trap air.

Re-bleed after each of the first few heat cycles to purge any air that may have been trapped somewhere in the system the first time around.

Live well,

SJW

cv67

I drill a few holes in EVERY thermostat of ea car I own bleeding will never be an issue. Do yourself a favor pull it out take 5 min doing it make life easier.

Cliff Harris

The factory uses a vacuum setup to fill the cooling system.

You can do something similar with this (I've got one):

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

bullguts

Just loosen the hose clamp at the thermostat housing a little bit , just enough to let the breeze out of the system . Take care champ , cheers .

JrRifleCoach

So few people take advantage of this simple procedure.
A couple of 1/8" holes and purging/burping is an easy task rather than chore.

And packing is a necessity that most don't bother with.
Rather they dump and fill. And complain the car is running hot.
Search for packing or burping. and maybe read the stickys....
By PLXR ---- Corvettes, Summer, and High Coolant Temperatures

Tom400CFI

"Packing"....


I fill mine, open bleeders close bleeders, then drive around at about 185*. Pretty darn easy.

hcbph

I had to do mine a couple of times due to a coolant leak that drove me crazy tracking down. Here's what I do: turn the heater controls to high. Take the radiator cap off. I have a cut up antifreeze jug I put in place of the radiator cap like a funnel and use a little duct tape to seal it to the top of the radiator. Start the engine and let it get to temp so the thermostat opens. When the thermostat opens and the coolant level drops, top it off. Remove the funnel and put the radiator cap on while still running. This is on a L98 and at this stage you should be done other than insuring there's a little antifreeze in the overflow tanks.

That's what I've done with my 86 and it's worked every time.

sluggballz

Thanks everyone for the replies. I've always found the LT1 to be a pain when refilling the cooling system. This was my second water pump, I've also replaced the radiator and had a heater hose blow plus replacing the opti cap a few times, and no mater what, it seems like it takes forever to get all of the air out. My 08, I had to replace the radiator and water pump at different times, simple as pie to get the air out.
My real question was, how the crap did the Bowling Green line fill these and not have to go through two or three heat cycles like is described in the manual. A few of you were nice enough to explain it for me and I appreciate it. I hope that for the near future my cooling system is up to par, now that everything, except the white plastic overflow tank has been replaced.
Thanks again!

RIC96

I recently had my 96 at the dealer to have the radiator replaced along with heater hoses and a flush and fill. Now, when I start it cold, the low coolant light comes on for a couple of minutes and the car runs a little hotter than it used to. The coolant levels seem to be ok, might I have air in the system?? Where are these bleeder valves?

sluggballz

On the LT1 it's on the thermostat housing , aka gooseneck, that the top hose connects to. The original had an area that fits a flat blade screwdriver, I wore mine out and had to replace the bleeder ( so I replaced the whole unit)
The new unit has a 8mm bolt head instead.

RIC96

Thanks slugg! Does it sound like I might have air in my system?

sluggballz

Of that, I'm not sure. There are people on the forum much wiser about these things than me. iirc, the low coolant sensor is on the bottom of the pressure tank on the passenger side, you might have one going bad. It's just a guess about it going bad though. Maybe someone else will chime in that knows more.
Good luck!

SJW

Remove the fill cap, and verify that the coolant level is sufficient. It probably is low. Top off as required. Bleed the system (pack rags under the bleeder screws before you crack them open, to capture the coolant that will escape, so that it won't get down onto the Opti below). Top off the coolant level again if necessary. Re-bleed after each of the next three heat cycles to ensure that all trapped air has been evacuated.

My '94 has two bleeder screws, one on the throttle body, one on the thermostat housing. IIRC, later C4s might have only one, but verify this.

Live well,

SJW

RIC96

Ok, I'll take a look after it cools off. Before I had the radiator swapped out it would run at 192 if I was constantly moving. Now it runs at 199. I don't want to take it back if there's something relatively minor that I can do myself.

JrRifleCoach

[QUOTE=sluggballz;1593161164 iirc, the low coolant sensor is on the bottom of the pressure tank on the passenger side, you might have one going bad. It's just a guess about it going bad though. Maybe someone else will chime in that knows more.
Good luck![/QUOTE]

My experience is that the coolant sensor is a "liquid switch". That is if the coolant submerges the contact, this completes a circuit and turns the light off. You can check this by pulling the connector off and check the light. Then touch the connector to ground and check the light again. One very important note is that this sensor will not remove without breaking! So if you're inclined to check it by removing, best have a spare in hand or you will be sorry.

eagle-157

Absolutely! I was concerned recently after replacing an Opti and wires. I was surprised when I filled the tank, added some antifreeze to the overflow closed everything up and started the engine. I let it come up to temp, ran it a few minutes at temp wit the heater on. shut it off and the overflow started bubbling. I kept checking the overflow and did not let it go dry. Started it again and ran it up to temp, shut it off and no more bubbles. I've been driving it the last couple of days and all is good. AntFarmer is right about this!