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425 V-8 `78 Deville-- Cooling system self bleeding or not?

2487 Views 6 Replies 4 Participants Last post by  larryinalabama
Been thinking of changing coolant in my `78 Deville 425 V8.
Is it self bleeding or not?
If not--what`s best way to get air out of system?
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Take the theromostat out, and take the bottom hose of the radiator and run a garden hose into the thermostat hole and radiator.

I spent the extra 1 or 2 dollars and alaways use distilled water when refilling.

Ive never had any trouble with air getting locked into a old GM car.

If you can find a radiator shop you may be able to get a new pet cock soldered in.
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Had another look at the drain plug closely and found the "nut" at the top of it just had to be loosened.
I forgot to relieve pressure with the rad cap first--loosened the drain plug nut and it the coolant exploded out of there
enough to shoot the drain plug a good 10 feet away.
I never thought I could move that fast---I got my hands in some cold water fast and luckily no burns--but
skin is real sensitive.
I wish I would have read your post first about distilled water.
Got a good deal on some extended life coolant from Napa and good to go.
Feel better knowing there`s fresh coolant in there and saved myself some $$$ doing it myself.
Glad your "OK" and found the plug.

I put the oil cooler gaskets on my 90 the other day and took a shower in oil. Im pretty sure that the car is now completely leak free, which is amazing for a 25 year old GM product, especially a Chevrolet engine.

I have to put the speedo housing seals on my 79 but cant seem to find the parts. Im going to the transmission parts place next time I go to the city. Any chance anyone would know the NAPA part numbers? Theres a o ring and a seal.
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