C4 Cooling System Bleeding

[Jim P.]

Hi all this is probably addressed somewhere but I haven't found it. Trying to bleed the cooling system on my 1994 LT1, but either I am not opening the screws far enough or not leaving them open long enough. About how many turns should you open them and about how long does it take before coolant starts to come out? Does it usually come out of the throttle body bleeder or the thermostat bleeder first? Because this may affect your answer I drained the radiator and got the knock sensor out on the passenger side but I couldn't get the one on the drivers side out. In total I drained a little more than 2 gallons of coolant.

Thanks.

[Keith B.]

Re: C4 Cooling System Bleeding

start the car with the radiator cap off. once the t-stat opens any air trapped will burp out

[Jim P.]

[Keith B.]

Re: C4 Cooling System Bleeding

I never did in the ten years and dozen or so times I've worked on my cooling system in my old 94

[Jim P.]

Re: C4 Cooling System Bleeding

Sounds a lot easier. Thanks

[Mark E.]

Re: C4 Cooling System Bleeding

I open the bleeder valve on the thermostat housing, fill until coolant comes out, quickly close the bleeder, then continue filling. After the engine has run with the thermostat open, let it cool then check the level and topoff as needed.

If you can't remove one knock sensor, flush out from the other sensor and radiator peacock until clear, close up and fill, run until the thermostat opens then repeat the cycle until clear. I recommend Evapo-Rust Thermocure.

[Jim P.]

Re: C4 Cooling System Bleeding

Thank you Mark. Approximately how many turns to open the bleeder valve at the thermostat? I am concerned about getting it so loose that it pops out. Also you don't bleed the throttle body screw at all? Thanks for your help.

[Matthew T.]

Re: C4 Cooling System Bleeding

Bleed screws locations are both #2's

[Jim P.]

Re: C4 Cooling System Bleeding

Thanks Matthew this is very helpful.

[Mark E.]

Re: C4 Cooling System Bleeding

Less than 1 turn to open.

I've found only opening the single bleeder does the job.

[Brad Hillhouse (37766)]

Re: C4 Cooling System Bleeding

Pro Tip -

Put a rag or paper towels in behind the waterpump and under the bleeders while opening the bleeder valves.
The output hole may be pointing in a way that sprays coolant directly behind the waterpump and onto the opti.

You don't forget lessons learned the hard way.....

Brad


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[Joe L.]

Re: C4 Cooling System Bleeding

Pro Tip -

Put a rag or paper towels in behind the waterpump and under the bleeders while opening the bleeder valves.
The output hole may be pointing in a way that sprays coolant directly behind the waterpump and onto the opti.

You don't forget lessons learned the hard way.....

Brad


[ATTACH=CONFIG]115118[/ATTACH]

Brad------


Yes, this is critically important for any LT1 or LT4 but especially critical for 1992-94.

In addition, a leaking waterpump, even at the early stages of leakage when it might not be readily apparent, can have disastrous consequences for the Optispark distributor.