Radiator and engine flush

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Adam in Wa
Technician 4th Grade
Technician 4th Grade
Posts: 127
Joined: Wed Mar 14, 2018 12:04 am
My garage: 48 Power Wagon
42 WC53
71 Dodge Challenger R/T
Location: Newport Washington

Radiator and engine flush

Post by Adam in Wa »

Last year I had my WC 53 radiator recored, and it was expensive. I knew My engine block needed to be flushed, but I didn’t want all the crud flowing into the new radiator core. I bought some fine metal screen (like the type used on some windows) and formed it around the upper radiator input neck. This turned out to be a good idea, because it caught a lot of crud.

I also replaced the water pump because it was leaking behind the pulley (it had a 1957 date code cast into it).

Before putting the truck back into winter storage I wanted to replace the water with a proper antifreeze.
After reading about radiator and engine flushing in the archives, in this and other forums, I decided to add some wood bleach, oxalic acid to remove the rust, and some automatic trans fluid, to the water in the system and run it for about twenty minutes before draining everything out and refilling it. The oxalic acid worked very well and the water was clear after one flush. But the ATF did nothing as it floated to the top of the radiator and would not mix with the water (of course, oil floats on water, duh!)

I refilled the system with straight coolant, no water. (Btw, I have been doing this for maybe 30 years on my other classic cars with no issues, and most new cars since the early 90s use straight coolant). After I put in the coolant I ran the engine for about a half hour and it would not even get to 165 in the radiator. My engine temp gauge read 180 but I saw very little flow in the radiator neck. I thought the thermostat might be stuck. I used a meat thermometer in the radiator neck (don’t tell my wife). Then I remembered that when I was in the Army, stationed in Germany, during the winter, I used to have to block the Jeep radiator with a piece of cardboard, except about 3 inches, to get up to temp and run the heater. Finally, I got it to 180 and confirmed the thermostat was open.
June J
Technician 3rd Grade
Technician 3rd Grade
Posts: 380
Joined: Fri Jun 18, 2010 6:27 am
My garage: 1942 Dodge WC 53
1941 Willys MB
1960 M38A1 Nekaf
Location: New Zealand

Re: Radiator and engine flush

Post by June J »

Hi Adam,
I note your comment about ATF in your coolant. Your right that will not emulsify in water. If you want to use a soluable oil suggest your use Shell bromus A, or go to your local maching shop and find out what they use as coolant in their lathes/tool post gtinders or crankshaft grinders.

Back in the early 1970's when I was an apprentice machanic, we used "Bars Leaks" as a coolant additive, this contained a soluable oil. It was quite tough on radiator hoses though.


1942 Dodge WC 53
1941 Willys MB
1960 M-38A1 Nekaf
Technical Sergeant
Technical Sergeant
Posts: 1498
Joined: Thu Jan 11, 2007 8:47 pm
Location: Allyn WA

Re: Radiator and engine flush

Post by Kaegi »

1/2 an hour not much time on these engines to get warm. they full length water jackets around cylinders and the massive volume of coolant takes forever to break a sweat. great set up. i have been out on mountain trails back in my off roading days in my WC 3/4 tons and been the only one not overheating. the toyotas seem to get hot first (puniest of radiators). then the others would follow.