Coolant change/ flush
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Pro
Joined: Feb 2024
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From: SOUTH EAST
Coolant change/ flush
I’m thinking of doing a coolant change but considering either going to the oil changing shop or doing it myself if the peacock is easy to access… is it a easy or somewhat easy to do
Pro
Joined: Sep 2024
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Its not too bad to do. I am not even sure my car has a petcock. But, removing the lower rad hose works too. Might as well pull the thermostat and do it fully. Run water through the thermostat housing with the lower hose removed from either the block or rad, flush until it is clear. Then do the upper radiator hose to through the top of the rad, out of the lower hose. Then grab a leaf blower and blow it through both the thermostat housing on the intake to clear out the block and do the same from the upper hose through the radiator (don't expect much water out of the radiator since its basically open now). Then pop the hoses back on except for the thermostat housing and fill the block through the thermostat hole (you'll wind up filling the block and most of the radiator that way). Pop the thermostat in and secure the upper hose and top off the radiator. Fire it up, let it cycle the fans. Shut down. Come out the next day and pop the rad cap and see if you need to add any more coolant.
Thread Starter
Pro
Joined: Feb 2024
Posts: 604
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From: SOUTH EAST
The old days you could’ve open the peacock then open the radiator cap and run a hose with water to it while the engine was running until you could see clear water coming out of the peacock
Pro
Joined: Sep 2024
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True, but that leaves water in the block. Which is why I use the leaf blower to get it all out.
Safety Car
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From: LeClaire Iowa
Shop vac flush works! - CorvetteForum - Chevrolet Corvette Forum Discussion
Racer
Joined: Oct 2013
Posts: 306
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From: VT
how do you plan to capture the old coolant? I was going to perform a coolant flush on my '86, but had no way to catch and dispose of it. especially problematic since we have a drilled well, and also a puppy who eats/licks everything.
Last edited by standswithabeer; Oct 11, 2025 at 08:55 AM.
Racer
Joined: Feb 2024
Posts: 267
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From: New York
I just did the water pump on my 90 L98. That fluid was always rusty. So with the water pump off, I drained the block. On the passenger side, remove the knock sensor. On the driver's side, remove the hose fitting from the bottom of the block to the oil filter adapter. With both of those fittings removed, I blasted water into each side of the block from the water pump openings. I got tons of rust debris out of the block. Took about 20 gallons of fresh water flushed through each side of the block to get it to run clear. Now, after reassembly, the coolant finally looks clean.
I think the only way to get the old fluid and rust out of the block is to remove those fittings at the bottom of the block skirts. Then flush and drain the block.
I think the only way to get the old fluid and rust out of the block is to remove those fittings at the bottom of the block skirts. Then flush and drain the block.
