Help! How do I Flush a Corvette Cooling System

[hokie04]

I am wanting to flush my 64 vette cooling system. I understand how to drain the radiator and back flush the core. But when I am refilling to do the actual flush do I install a T in the heater hoses or just keep filling the expansion tank and let the radiator and heater hoses pull the liquid into the radiator? Without an actual cap on the radiator it seems that I will need to do this with engine running so the water pump can get the liquid to the radiator.

 

[Bill Wilhelm]

Hokie04, Consider drain/flush the engine block also, if you are going to do it, do it right. Remove the lower left and right block drain plugs hidden under the "V" shielding. There's a good chance no coolent will flow out when the plugs are removed because of scale buildup inside block. If this is the case, use a screwdriver or other tool to unplug both sides of block. Remove thermostat. Insert an adapter screwed onto a garden hose into either side of engine block, turn on water, when water begins flowing out thermo housing start engine. Run a few minutes then switch garden hose to other side block drain hole and run engine again. After block and radiator have drained, refill with coolent and install new 180* thermo. This should take care of things for quite a while. Bill

 

[hokie04]

Thanks Bill, I didn't even think about the block. So I have to flush the block, back flush heater core and flush radiator. Should I use a flushing chemical with water or just plain water? And are all refills of system through the expansion tank and I assume that is with engine running to circulate the water?

 

[Bill Wilhelm]

Yes, I would use a flushing chemical. Directions on the can may suggest running the car for a few minutes before draining. I would run motor for some time (one hour?) or a short trip down the interstate before draining. Use care not to get any of this in your eyes when draining.
As for filling system with coolent, I like to fill through the thermo opening (with thermo removed) till coolent level is with lip, then install gasket & thermo. This way there are no air pockets in the block. Then fill expansion tank to half full and start engine, if coolent level drops, refill to half full. You should be good to go. Back to work! Bill

 

[Verle]

Hokie04,

Pay attention to what Bill says.

He knows about flushing things.....

Verle

 

[JohnZ]

As for filling system with coolent, I like to fill through the thermo opening (with thermo removed) till coolent level is with lip, then install gasket & thermo. This way there are no air pockets in the block. Then fill expansion tank to half full and start engine, if coolent level drops, refill to half full. You should be good to go. Back to work! Bill

Yup, I use the same method - even modified a plastic funnel for it - cut the end off square so it stands up by itself in the thermo opening, and drilled holes in it so I can watch the coolant level rise.

 

[hokie04]

I appreciate all of this great information! I just want to be sure of the sequence of this process.
1) Drain antifreeze via radiator drain.
2) Refill with water and add flush cleaner.
3) Take car for a short drive with cleaner in engine.
4) Drain again through radiator.
5) Remove two heater hoses and back flush heater core with water through outlet hose.
6) Remove engine plugs and thermostat housing.
7) Flush each engine plug hole until clean water runs out of thermostat hole.
8) Refill with green antifreeze for Alum. radiator through the thermostat housing.
8) Install new 180 thermostat with housing and new gasket.
9) Fill expansion tank half full and top off as needed.
Did I miss anything?

 

[Bill Wilhelm]

Hokie04, The only other thing you might do is inspect all your rubber hoses for damage and cracks. Since you will have the coolent removed now is a good time to replace any old or damaged hoses. Bill

 

[hokie04]

Bill, that's a good point. I just purchased this car and the owner replace all the hoses, clamps everything factory correct 15 years ago. The car have been drive only a few hundred miles since. The hoses look brand new but I am thinking what about all the years of sitting there? There is no cracking , bulging or any signs of wear.

 

[Bill Wilhelm]

Hokie04, If those hoses are 15 years old I wouldn't care what they look like. I would not trust them to go around the block. IMO you should replace all of them. Have a good weekend! Bill