Do I really need to have my radiator rodded?

['41 Fat Bottom Girl]

While thinking about my flathead rebuild coming up, I have a question about my original '41 radiator.

I would hate to take a chance at one of today's rad shops if I don't have to. In 20 plus years my engine has never overheated even on a 100+ F day, got a 7 lb cap on the rad and it has never blown steam or lost coolant between coolant changes. I do new coolant, 50-50, every 2 years. Has a 180 F thermostat and that's where she runs.

Careful inspection of the core inside and outside with a magnifier glass shows no signs of any  leaks.

With later year vehicles, while an engine is out I have always had the rad rodded and pressure tested- but with my '41, I would really like to leave it alone. 

Opinions?

 

(quote my wife read to me-"When you're dead, you don't know it. It is just people close to you that feel pain. It's like when you are being stupid"

hmmm... wonder if she was relating something funny, or trying to make a point...)

BTW- no opinions on that, please. Just about the radiator, thank you!

 

[belvedere]

I think I would leave it alone.

[ptwothree]

Not sure if a honey comb rad can be rodded out.

[Cold Blue]

If it ain't broke don't fix it. Sounds to me like it performs as designed, it doesn't leak, and it is original. I would leave well enough alone.

[Merle Coggins]

4 hours ago, ptwothree said:

Not sure if a honey comb rad can be rodded out.

 

Quite true. It could possibly be hot tanked and flushed, but if it hasn't caused any issues I'd flush it myself and preserve it's integrity.

[Sharps40]

5 hours ago, ptwothree said:

Not sure if a honey comb rad can be rodded out.

 

 

They honeycomb/cellular radiators have the same tubes as the fin and tube rads.   Just can't see em as well till the top is off.   So, yes, you can rod out a cellular/honeycomb radiator.  The water moves through tubes just like a modern radiator but the outward appearance of a honeycomb/cellualar radiator would make one think it moves through millions of tiny chambers.  

 

As for whether or not.....its going to a newly rebulilt engine????,  then, yep, rod out the radiator and if it is thin or fails, rebuild it or replace it.

Edited May 29, 2019 by Sharps40

[Dan Hiebert]

To be on the safe side, at least have it pressure tested, and most shops can also check the flow rate through it.  Neither of those require it to be taken apart.  It may be nice and reliable, but it's still 78 years old.  Good to start there, that way - as noted before - if it isn't broke, no need to fix it.  If it's not up spec, then you can have them address whatever issues it has.  

[Merle Coggins]

Here's a good look at the inside of a honeycomb radiator, and how they're made.

 

 

 

[greg g]

There is a very simple flow rate test illustrated in the service manual.  Did you try it? Well it's in the 46 to 52 manual, if it is not in the earlier manuals, the procedure is likely the same.  Du you have the service book for you car?

Edited May 29, 2019 by greg g

['41 Fat Bottom Girl]

In my '41 D19/ D22/ D24 shop manual, there are flushing instructions (pulsating water inlet to outlet, then reverse flush outlet out to inlet) for the radiator but doesn't outline a flow test. Would you mind a quick description of the test you found?

Thanx much! 

[greg g]

Drain the coolant, disconnect the main hoses.  Block the lower outlet with a rag, or other suitable item.  Fill the rad with water until it comes out the top hose.  Then unblock the lower outlet.  The. Flow of water coming out of the radiator should form a column of water about five inches tall as it flows out until the radiator is down to about 1/3 full.

[soth122003]

Hey 41,

 

The flow test is basically plug the inlet and outlet, fill with water and remove the bottom plug and look for the water to flow out the bottom at about 6 inches high. That being done, if you have a low flow rate an old radiator mech told me to use dawn dish soap to soak the rad about 24 hours and then flush and test again. That  will break up any oily or grease deposits built up from using rust inhibitors or such. I also used about 1 quart of CLR to remove rust and limescale deposits. Basically for either plug the rad and fill with water and soap or water and 1 quart of CLR  and let it soak. For the soap 24 hours and the CLR about 3 hours rotating the rad to get full coverage inside.

 

Joe Lee

['41 Fat Bottom Girl]

Sounds good. I will do that.

Thanx much for the info and advice, all!

[_shel_ny]

I would refrain from having any pressure testing done unless you are dealing with a shop that is familiar with these radiators. They could easily damage it. 

 

If you have an original set up in a '41 it should not be a pressurized system. Your 7lb cap is meaningless.

['41 Fat Bottom Girl]

Everything is original.

So there is no significant back-pressure within the radiator when running temps are normal?

There is a little cylindrical projection at the top center of the rad from which the overflow tube exits.

Is there anything inside this, or is it an unobstructed path from inside the top cap to the overflow?

Thanx for the education...

[Sharps40]

Unobstructed path.   

[greg g]

Your overflow location assures your system can not build pressure as it is above and separate from the filler and cap.