View Full Version : Flushin the engine and radiator on a 1976 500ci

07-31-13, 07:39 PM
Anyone got tips for flushing the coolant out and cleaning the pathways on a 1976 500ci?

cadillac kevin
07-31-13, 07:45 PM
For flushing, I use the bolt on the bottom of the radiator for draining the radiator. this will get rid of most of the old coolant. I guess you could pull the top hose, and run fresh water through it and have it dump out through the lower hose of the radiator (don't quote me on this, but it should work)

07-31-13, 07:48 PM
I've heard running some CLR through it helps

07-31-13, 09:44 PM


I guess what I'm really asking is how to get the water ways cleaned out...this engine has been sitting for some time and there is probably quite a bit of build up in the system. Looking at the radiator with the cap off I can see quite a bit of build up. S'pose I could pull the rad and have it cleaned. Just wondered if anyone had experience flushing the cooling system?

07-31-13, 11:00 PM

CLR: http://www.thecarycompany.com/containers/facility/clr-multisurface.html?gclid=CJWMqKig27gCFRDZQgodAB4A7A


Obviously you dont need industrial strength stuff, but now you know what it is. Ie never heard of it bekng used in an engine block, but I imagine it would do a really good job cleaningg it out. I was thinking of using it on my radiator. Gotta make sure you rinse well.

07-31-13, 11:24 PM
They sell system flush at the parts stores, just pull the thermostat and follow the directions on the bottle. I also use this tool that hooks up to compressed air and a water hose to help flush it.
I forget the name of the tool, but I know it says Sears on it, I think it is from the 60s or so, I wonder if they still make them. Anyhow they really help.

08-01-13, 01:38 AM
You could flush the radiator and engine separately. Take both radiator hoses off, flush the engine from the thermostat inlet, flush the radiator from the upper inlet. Put the lower radiator hose back on and fill the engine from the thermostat inlet.

08-01-13, 09:05 AM
OK, I'm getting ready to flush everything this weekend. Also change out the oil and filter for both transmission and engine...new food for the beast! Thanks guys. Gosh really appreciate this forum and the help it gives us :-)

08-05-13, 11:22 AM
Hit a hitch...bad electrics couldn't get started. New battery may solve the issue. So, next weekend...til then......

cadillac kevin
08-05-13, 11:59 AM
Change the radiator hoses while you're at it. They probably need to be changed and it is cheap insurance from a failure on the road.