Ford GPA vs Ford GPW radiator (inside photos)

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Ford GPA vs Ford GPW radiator (inside photos)

Post by YLG80 » Fri Nov 18, 2016 2:29 am

Hello,
My GPW jeep is equipped with a Ford GPA radiator.
No problem so far, but I've a question regarding the GPW vs GPA radiator capacity.

Do they have the same capacity?

The main difference I can see, is the shorter GPA deflector around the fan and the deflector attachment with screws.
Yesterday, I've flushed the coolant, and I was able to refill the circuit only with 9 liters i.o 10.5 liters of coolant.
This could come from residues in the bottom of the radiator or from a difference in the dimensions.
There are not many information or pictures of the GPA radiator.
Thanks for any info.
Yves
Last edited by YLG80 on Tue Jun 05, 2018 10:18 am, edited 1 time in total.
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Re: Ford GPA vs Ford GPW radiator

Post by Bill M » Sat Nov 19, 2016 8:03 pm

Hello Yves,
The capacity for both GPW and GPA cooling systems is listed by the Ordnance Dept. at 11 Quarts, 9 -1/4 Imperial Quarts, and 10.4 Litres so that rules out the radiator being the culprit assuming it is in it's original state.
It could be residue on the bottom of the radiator tank or a build up of scale at the bottom of the block water jackets. If the block drain cock is blocked then that is an indicator of the water jacket state.
Hope this helps.
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Re: Ford GPA vs Ford GPW radiator

Post by YLG80 » Sun Nov 20, 2016 10:42 am

Hello Bill,
Thanks for that information.
Yes, the radiator looks in the original state.
The engine has just been completely rebuilt and the water jacket was thoroughly cleaned up.
There was no problem to drain the coolant from the engine water jacket and the radiator.
So either it could be air trapped in the system or a radiator issue.
In fact there is no overheating problem. I was just changing the antifreeze before the winter.

When I press the lower rubber hose, it looks too soft to be full of water after the system refill.
The thermostat has a little hole, so the coolant should get into the jacket, after a while.
I'm going to slightly crack open the temperature sensor to see if air is coming out when the engine is running.
Thanks.
Yves
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Re: Ford GPA vs Ford GPW radiator

Post by Donovan » Sun Nov 20, 2016 11:57 am

Bill,
Something wrong here. My GPA manual puts the capacity of the cooling system at 13 US quarts or 10-3/4 imperial. I have not personally measured how much went into my GPA cooling system but I seem to recall that it took more than 3 gallons of coolant. I think the GPA radiator was slightly bigger and had a six bladed fan to deal with running the motor at high rpm while in the water and not going very fast. They were notorious for overheating while in the water.

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Re: Ford GPA vs Ford GPW radiator

Post by Bill M » Sun Nov 20, 2016 1:30 pm

Donovan wrote:Bill,
Something wrong here. My GPA manual puts the capacity of the cooling system at 13 US quarts or 10-3/4 imperial. I have not personally measured how much went into my GPA cooling system but I seem to recall that it took more than 3 gallons of coolant. I think the GPA radiator was slightly bigger and had a six bladed fan to deal with running the motor at high rpm while in the water and not going very fast. They were notorious for overheating while in the water.

Donovan.
I found the 11 qts in an Ordnance report from mid-late 1943, I will check it out, it quite possible could have been an early GPA under test. Apologies for the confusion. :oops:
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Re: Ford GPA vs Ford GPW radiator

Post by hell-fire » Sun Nov 20, 2016 2:05 pm

You will be surprised how much crud and junk gets caught in these old radiators, the one out of my MB came back 5 pounds lighter after its re-build and capacity was higher.
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Re: Ford GPA vs Ford GPW radiator

Post by YLG80 » Tue Nov 22, 2016 1:22 pm

Thanks for the good advice.
I'm going to weigh the radiator before trying again to remove some crude that for sure remains at the bottom.
Thanks
Yves
Last edited by YLG80 on Tue Jul 17, 2018 1:03 am, edited 1 time in total.
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Re: Ford GPA vs Ford GPW radiator

Post by YLG80 » Tue Jun 05, 2018 10:17 am

Off a small spark, a great fire !
I've decided to change the radiator cap that was on the jeep and replace it with a correct GPW cap repo.
The radiator was not pressurized before with the old cap.
Once pressurized with the new cap, a water leak appeared below the top water tank header :mrgreen: !
I'm pretty sure that some Stop Leak was added in the past :D ! It was ejected by the pressure.

I've bought that very nice new GPW repo radiator with the correct core and placed it in the jeep.
So far so good, no problem anymore, of course.

But I've asked to a local shop to try to repair the GPA radiator. It should not be that difficult.

The guy called me one month and a half later to tell me that he was unable to repair that radiator.
"Too old and too corroded", he said. :shock:

Now that my Jeep is OK, I've plenty of time to repair that radiator myself.
Here is what I've found after removing the top tank :( :(!
This was a rather "brute" repair attempt.
FORD_GPA_RADIATOR_1.JPG
FORD_GPA_RADIATOR_1.JPG (198.82 KiB) Viewed 804 times
Portion of the core tin plugged
FORD_GPA_RADIATOR_CORE_2.JPG
FORD_GPA_RADIATOR_CORE_2.JPG (218.4 KiB) Viewed 804 times
Core unplugged
FORD_GPA_RADIATOR_UNPLUGGED_3.JPG
FORD_GPA_RADIATOR_UNPLUGGED_3.JPG (248.62 KiB) Viewed 804 times
I guess it wouldn't have hurt the GPW, because that GPA radiator has a bigger capacity.
But it's not nice.
At least, the photo confirms the 4 tubes core in the GPA radiator.

It looks not too old and corroded. A thorough cleanup down to shiny brass and copper and re-soldering should be OK.
An additional reason to do the job myself :D .
Last edited by YLG80 on Mon Dec 24, 2018 7:09 am, edited 3 times in total.
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Re: Ford GPA vs Ford GPW radiator (inside photos)

Post by YLG80 » Wed Jun 06, 2018 7:53 am

My plan is to remove the top header because it's nearly impossible to repair solder cracks on the inner tubes.
[CORRECTION, I will not do that. It's too difficult.]

Any advice. Has it already been done ?? Ralph, John? Lew ?

If I remove the header, I can clean each copper tube with a soft wire brush and Dremel.
Then it will be easy to solder the thing when it is shiny-clean !
Last edited by YLG80 on Mon Dec 24, 2018 7:11 am, edited 1 time in total.
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Re: Ford GPA vs Ford GPW radiator (inside photos)

Post by YLG80 » Sun Jul 15, 2018 3:10 am

Only a little progress with the GPA radiator repair. I'm thinking to the method rather than acting :) :)!
I've found a little plastic container (garden accessory from my wife) that could contain just enough NaOH+ H2O to strip the paint from the tubes and header.
I've cleaned up the top header with a solution of NaOH 10% + hot water 40-50°C to strip the painting from the core tubes where they are soldered to the header and it also removed foreign matters.
On hour was enough and I've used a spiral brush between the tubes to add a mechanical action.
Not sure that it is necessary, though.

The header cleanup is quite effective: (the radiator is upside down so that's the upper part shown in the bath :wink: )
RADIATOR_STRIPPING_PAINT_NAOH.JPG
RADIATOR_STRIPPING_PAINT_NAOH.JPG (228.26 KiB) Viewed 694 times
STRIPPING_PAINT_AND_OTHERS.JPG
STRIPPING_PAINT_AND_OTHERS.JPG (247.29 KiB) Viewed 694 times
That looks good!
Clean_from_paint_1.JPG
Clean_from_paint_1.JPG (236 KiB) Viewed 694 times
There is a "blooming" problem with the tin solder which is not unusual after a so long period !

Now I'm going to use HCl / Muriatic acid as used by Lew to remove the oxydation.
I will do that only when ready to resolder the tubes to the header.

More on that later.
Yves
Last edited by YLG80 on Tue Sep 17, 2019 6:31 am, edited 1 time in total.
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Re: Ford GPA vs Ford GPW radiator (inside photos)

Post by YLG80 » Mon Dec 24, 2018 4:24 am

Still thinking to my GPA radiator before entering into action :lol: !

The problem with the repair of a radiator is that you have to resolder the water tank each time you want to test the radiator for leaks.
That's really boring and it's not good to heat up the radiator parts twice for each test.(soldering & desoldering)
I've found an easy way to detect the tiny holes located near the header grid.
There were no leaks detected past the middle of the core up to the lower tank.

You have to use one of these new very powerful tactical LED flashlights.
There are various models and they are all very powerful and focused.
You put the LED light close to the tubes and you check for light leaks on the other side.
The LED light is so focused that you illuminate only the little area that you want to inspect.
IMG_7773s.JPG
IMG_7773s.JPG (254.96 KiB) Viewed 586 times
It's really amazing how easy it is to detect tiny holes in tubes near the grid or cracks in the solder joints on the header grid (bloom corrosion problems).

I've immediately found the hole causing the leak.... and I've found a second hole on the other side of the radiator, likely opened after cleaning.
Here is the tiny hole near the place where the coolant leak was visible when the radiator was in the jeep..
Now I know exactly where this darn hole is located.
IMG_7770s.JPG
IMG_7770s.JPG (237.35 KiB) Viewed 586 times
And inspecting the rest of the grid, I've found another one on the other side.
IMG_7775s.JPG
IMG_7775s.JPG (233.03 KiB) Viewed 586 times
Now that I know where the enemy is hidden, I can start the attack :evil: .

I will do like Lew described in another very interesting and well documented post.:
Cleaning with 20° HCl acid, baking soda+water to neutralize, fluxing the header grid on both sides and then soldering/wetting both sides of the header.
After that, another LED light inspection and repair the two detected tiny holes which are slightly above the grid level on the core side.
Finally, cleanup and remove any flux residues prior to solder the tank.

To be continued ./..
Last edited by YLG80 on Sun Sep 22, 2019 1:02 pm, edited 1 time in total.
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Re: Ford GPA vs Ford GPW radiator (inside photos)

Post by 70th Division » Mon Dec 24, 2018 9:41 am

Hello Yves,

Fascinating report on repairing your GPA radiator !
I really enjoyed the post :D .
I like the use of the tactical flash light .

Merry Christmas 2018 !!

Best Regards,
Ray

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Re: Ford GPA vs Ford GPW radiator (inside photos)

Post by YLG80 » Tue Sep 17, 2019 7:22 am

I've decided to continue with the GPA radiator restoration.

As shown here above, it's rather easy to detect where there are tiny holes in tubes or missing solder around the tubes.
After cleaning with NaOH, I've detected no less that 25-30 holes, all in the upper part of the radiator near the header.
Most of them are missing solder, but a few are holes in the tubes.
I believe that the holes are all concentrated in the upper part, because that is near the coolant surface in the radiator.
Old coolant becomes more corrosive and the oxygen near the surface makes the rest.

That radiator was treated with Stop Leak that can be found in the tubes.
That product is quite effective.
It was removed when I've treated the header in the caustic soda- NaOH bath to remove the paint and other foreign matters.

Now it's time to repair the holes with tin solder ... and solder wick.
Before soldering with tin, the header and the top of the tubes oxidation have to be stripped with HCl / muriatic acid.
Same process as the one described by Lew in another thread.
The goal is to prepare the header and the top part of the tubes to be soldered.
The top part of the radiator soaking in HCl.
Muriatic-HCl.JPG
Muriatic-HCl.JPG (159.36 KiB) Viewed 333 times
Then it will be cleaned up with clear water and dried up.

Now I need to re-create the solder joints where they are missing or leaky.
I've first applied liquid flux on the header, total surface.
Here is a picture of the soldering process.
I've used a torch with a large tip for the first general tin wetting and a fine tip for the specific tubes repair.
The header is always heated up from the bottom side on the images.
The tin solder has never to be touch by the flame. The solder melts against the metal when the metal is hot enough :wink: !
SOLDERING.JPG
SOLDERING.JPG (29.08 KiB) Viewed 333 times
A good solder can be seen via the capillary effect like this. The solder goes up and "wet" the tubes:
Capillary-effect.JPG
Capillary-effect.JPG (168.06 KiB) Viewed 333 times
capillary-effect-tubes.JPG
capillary-effect-tubes.JPG (217.26 KiB) Viewed 333 times
The process is easy and quite fast : you progress slowly from the left edge to the right edge while adding solder on the top of the header.

The you wait until the night, and in the darkness you check again the leaks with the flashlight.
There were still many holes above the solder joints, in the tubes.

It's difficult to fill up a hole with tin solder, because the tin solder is sucked at the bottom in the solder bath when you heat up the header.
So I've used a little trick : solder wick.

Solder wick used in electronics ... and yesss, it's Made in USA :wink: !
solder-wick.JPG
solder-wick.JPG (99.9 KiB) Viewed 333 times
I cut what's necessary to surround the radiator tubes and I apply that piece of wick directly against the tube.
wick.JPG
wick.JPG (84.28 KiB) Viewed 333 times
Then I add the tin solder which will be sucked by the wick which in turn will be solder to the tube.
I've used tin solder wire with resin in the core.
wick soldered.JPG
wick soldered.JPG (106.62 KiB) Viewed 333 times
That wick patched a large hole. Yessss!
And the tube is still free form solder in the inside.
Easy to solder, not so easy to place the wick around the inside tubes.
There are 4 rows in a GPA radiator.

By the end of the restoration, the header will be soaked in baking soda to neutralize the acid and flux residues from the soldering process.

Then it will be time to re-solder the tank and pressurize test the radiator.
Last edited by YLG80 on Wed Sep 18, 2019 12:15 am, edited 5 times in total.
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Restored as 1st Army 759th LT B21
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Re: Ford GPA vs Ford GPW radiator (inside photos)

Post by YLG80 » Tue Sep 17, 2019 7:27 am

For those who are interested, I've saved the complete radiator repair description from Lew in a single pdf file.
When a post is very interesting like this one, I always save it in my hard disk :wink: .

Today most of Lew's pictures are lost or too blurry in his thread.
http://forums.g503.com/viewtopic.php?f= ... ld#p804535

Yves
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Re: Ford GPA vs Ford GPW radiator (inside photos)

Post by YLG80 » Mon Oct 21, 2019 1:37 am

Sad conclusion : the original radiator core is lost.
I've patched many holes and completely resoldered the top head.
During each test, the pressure blown news holes in the grid which means that the tubes are now too thin.(Corrosion by the old coolant)
Except on hole, all problems are located at the top of the radiator near the header, at the interface between the coolant and the air.
That GPA radiator needs a new core.
Yves
Ford GPW 164794 1/4T 12-7-43 - Frame# GPW*239762*
ACM I body#198443
Restored as 1st Army 759th LT B21
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