question CCKW - Radiator Expansion Tank Bottle ?

I know the purist may be offended by the suggestion (so if you are please don't reply), but does anyone have, heard of, or seen a (presumably post war) mod to a CCKW to fit a radiator expansion tank bottle ?

Kind regards

Ian

Yup, and not post war either, standard practice. In fact the DUKW came with one as standard so contact your local DUKW owner for a look.

I think the kit consisted of a sealed radiator cap ( for the main radiator ) and a line to the overflow tank, which you put the normal pressurised radiator cap on.

In use any overpressure in the main radiator blew water into the overflow tank, which vented off excess steam as normal, and when the system cooled it drew coolant back into the main radiator.

The part numbers will be in the DUKW listings, but I know they were found on the ordinary non-amphibious GMCs as well

Is the 'desert cooling kit' used on jeeps a vehicle specific item or was that used on other vehicles?

The TM9 DOES reference an expansion tank. TM9 4/44 Page 76:

Gordon and Deadline

Thanks for that info, great stuff. Next time I'm talking to Rex Ward I'll ask him if he has the right bits in stock

Kind regards

Ian

Gordon and Deadline

 

Thanks for that info, great stuff. Next time I'm talking to Rex Ward I'll ask him if he has the right bits in stock

 

Kind regards

 

Ian

Hi Ian,

Can I politely ask why you are looking into this? Is there a problem with the truck?

Regards - Mike

Hi Ian,

 

Can I politely ask why you are looking into this? Is there a problem with the truck?

 

Regards - Mike

Mike

I hesitate to answer for the fear of bringing the wrath of the purists down upon me, but there are three reasons:

1. I've had bad experinces in the past with coolant levels when I was running some of my older cars.

2. I find it very annoying that I can't check the collant level without having to top-up. In doing so of course you end up wasting anti-freeze solution when it blows it out, plus you can't monitor it journey to journey, if you have a problem.

3. I do have some concerns with the truck, although these might be explained by the Thermostat playing up over these last months, and now stopping working all together.

Kind regards

Ian

Hi Ian,

I had/have similar issues... I'm unable to confirm the radiator level by looking in the rad cap so I top up 'just in case'. Then I find the rad vents the excess water after my journey. I am gradually coming to the conclusion that there is nothing wrong and the water is just finding its own level... the fact being that its own level is just below where I am able to confirm visually.

I've tried sticking my finger in, shining a torch in and doing all of the above whilst rocking the truck, just in case its sloshing about just out of sight.

I've recently replaced the coolant, this was after done a couple of trips without topping up the radiator (so the water level was out of sight). However the amount of coolant that I drained was roughly the same as what the TMs specify. But it doesn't hurt to be paranoid!!

Jon

Just on the way past, then.

None of my GMC, DUKW, or Dodge stuff has ever done lots of miles, and I'm not very religious about topping up, but from memory most of my GMC product seems to vent coolant out to a level ( when cooled again ) that is roughly level with the top fin / sheet visible inside the radiator neck.

All the knowledgable GMC / DUKW owners I've ever talked to stress the requirement to let the engine idle and the exhaust manifold to cool down a bit with the engine running after working it hard. DUKW enthusiasts will know that when you are really working the engine at night you can look down past the drivers feet to the bottom of the hull, as see the cheerful red glow of the exhaust manifold reflected off the bottom of the hull - or any water therein.

....I've tried sticking my finger in, shining a torch in and doing all of the above whilst rocking the truck, just in case its sloshing about just out of sight......

Yes, I do that all the while, rocking it usually gives you a pretty good idea where the level is! :-D:-D:-D

You most likely need a new radiator cap, or your radiator cap is not sealing on the stamped lip on the neck.

I'm not sure you can replace the gasket on the bottom of the cap... so a new one might be required.

My jeeps (a 42 GPW and 66 M35a2) don't have overflow tanks, and in the 100F+ (35-40C) summer temps I still don't lose any fluid.

You might also have some clogged coolant tubes in the radiator, but the quick and easy part to check is the cap... any you should always have a spare cap in the spare parts box.

You most likely need a new radiator cap, or your radiator cap is not sealing on the stamped lip on the neck.

 

I'm not sure you can replace the gasket on the bottom of the cap... so a new one might be required.

 

My jeeps (a 42 GPW and 66 M35a2) don't have overflow tanks, and in the 100F+ (35-40C) summer temps I still don't lose any fluid.

 

You might also have some clogged coolant tubes in the radiator, but the quick and easy part to check is the cap... any you should always have a spare cap in the spare parts box.

Never heard of changing the seal on a rad cap, if it's faulty you just change the whole cap. However I don't believe the cap has anything to do with it, if you fill a radiator to the top when the water heats up you get expansion and steam, this causes pressure and it has to vent hence on modern vehiclesexpansion taks are fitted as standard on older vehicles such as a GMC or a jeep they simply vent onto the road. When groups such as the SAS and LRDG used vehicles over long distances in the Western Desert during WW11 water was at a premium so they fitted wxpansion tanks to collect the water from condensed steam. Hope this makes sense.

Jeeps have a separate seal that goes with the cap. And not knowing if you have an original cap it could be as simple as replacing the seal.

The CCKW radiator cap is supposed to vent at 5psi IIRC. If your cap is old or defective, or has a poor seal you could be venting at a much lower pressure allowing water to escape via the overflow tube.

If the cap seating flange is damaged nothing you do will keep water in the radiator, it will have become an open system and boil off.

Under normal circumstances you should not be venting water. After a fill and run up to temp the system finds its level (which means you should be able to see water by looking down the filler neck). If your CCKW radiator runs lower than that you have could have some issues:

Bad cap.

Blocked radiator core tubes.

Crack/leak/weep

And here comes the TM cite:

http://www.tm9-801.com/searchTM10-1562/TM10_cache/47.pdf

GM Part number 846732 - Gasket, radiator cap.

You may need a new one... on in a few instances.. you may even need it outright.

Jeeps have a separate seal that goes with the cap. And not knowing if you have an original cap it could be as simple as replacing the seal.

 

The CCKW radiator cap is supposed to vent at 5psi IIRC. If your cap is old or defective, or has a poor seal you could be venting at a much lower pressure allowing water to escape via the overflow tube.

 

If the cap seating flange is damaged nothing you do will keep water in the radiator, it will have become an open system and boil off.

 

Under normal circumstances you should not be venting water. After a fill and run up to temp the system finds its level (which means you should be able to see water by looking down the filler neck). If your CCKW radiator runs lower than that you have could have some issues:

 

Bad cap.

Blocked radiator core tubes.

Crack/leak/weep

 

And here comes the TM cite:

 

http://www.tm9-801.com/searchTM10-1562/TM10_cache/47.pdf

 

GM Part number 846732 - Gasket, radiator cap.

 

You may need a new one... on in a few instances.. you may even need it outright.

As regards the gasket I stand corrected but I would hesitate to use a NOS gasket or cap as by now they would be 50 plus years old and in my opinion would probably have deteriorated. Obviously it would lack originality but I would prefer to use a modern equivalent rather than suffer a catastrophic failure. I would suggest that there are too many variables to state categorically that you have an issue with the radiator unless with a serviceable thermostat and rad cap fitted the vehicle is suffering overheating problems. I think this thread it getting too far into the realms of possibilities rather than the reality of the original problem.

Further to my last post I think we should now wait for Vulture's report on the vehicle after he has fitted the new thermostat and then deal with any other eventualities if and when they occur. I now await Vulture's report with interest.

NOS termostat would be OK. They would not go bad on the shelf (other than a manufacturer defect) but by the operation of the springs and thermal mass used to open them (ie if it doesn't move, it won't wear out).

I don't know of any repro caps that have that arm spot welded to it.

Further to my last post I think we should now wait for Vulture's report on the vehicle after he has fitted the new thermostat and then deal with any other eventualities if and when they occur. I now await Vulture's report with interest.

Yeah but he needs to know that if he gets a new cap, it needs to have the fibre gasket otherwise its not going to seal even with a new cap.

There are many and varied imponderables with the cooling system, anything from a blown gasket to an external leak.

I think that the first thing to establish might be that you have not got a blown head gasket. If the radiator is filled to the top and you allow the engine to tick over for several minutes, and you dont suffer a great eruption of water from the rad all at regular intervals, then you can assume that the gasket is o.k. You could be suffering from a blocked rad, the fan belt may be loose, or a defective cap, but one thing is for sure, you certainly dont need an expansion tank in this country.

Good luck and may your troubles be minor.

Further to my last post I think we should now wait for Vulture's report on the vehicle after he has fitted the new thermostat and then deal with any other eventualities if and when they occur. I now await Vulture's report with interest.

Degsy, brace yourself ! One will be appearing on the Temperament gauge puzzle thread very shortly (just need to upload some photos)

Yeah but he needs to know that if he gets a new cap, it needs to have the fibre gasket otherwise its not going to seal even with a new cap.

Deadline

Looking at the existing cap I can't see any gasket... I'll post a photo on the Temperament gauge puzzle thread

There are many and varied imponderables with the cooling system, anything from a blown gasket to an external leak.

I think that the first thing to establish might be that you have not got a blown head gasket. If the radiator is filled to the top and you allow the engine to tick over for several minutes, and you dont suffer a great eruption of water from the rad all at regular intervals, then you can assume that the gasket is o.k. You could be suffering from a blocked rad, the fan belt may be loose, or a defective cap, but one thing is for sure, you certainly dont need an expansion tank in this country.

Good luck and may your troubles be minor.

Big Ray

I've did the tick over check for blown headgasket, a month or so back, when I started to become suspicious of something amiss... Nothing too see. As for my troubles being minor, time will tell...

Deadline

 

Looking at the existing cap I can't see any gasket... I'll post a photo on the Temperament gauge puzzle thread

I do think this is how the original rad caps are made, without any kind of gasket except for the brass / copper flange part of the rad cap which sits on the top lip of the rad filler cap hole. This is how mine is and had no problems with using water or over heating over the past 15 years of long trips at 40 ish MPH, dual carriageways ect. to France and loaded.

Also regarding the filling of the rad, there is a baffle over the top hose inlet to the rad so you cant see the water level through the filler cap, all I do is top it up till you can see it then put cap on and use it, excess water is then pushed out through the overflow and then it stops once its at the correct level. Check every now and then and that's about it.

I'll repost this from another thread I found talking about jeep radiator caps.. still 100% applicable to CCKW caps.

"Hmm....I think we need to learn a bit more about how the radiator cap works. If the gasket in the NECK of the radiator is between the CAP and the Inner ledge of the neck then that is where the pressure seal is created, if my understanding of the radiator cap is correct, then it is the EXPANSION of the coolant (not the temperature) to the 4 lb+ threshhold the opens the cap/gasket/neck and allows coolant to rise higher in the neck of the radiator. The thin brass disc has sealed the CAP to the TOP of the radiator and thus the expanding coolant has only the overflow tube available to expand into.

So I am of the opinion the the PRESSURE in the radiator and in the cap is not created by the brass disc, but by the gasket down further.

Therefore if your brass disc has a crack in it, the PRESSURE seal of the cap is not effected since that is a function of the gasket, the lower part of the cap and the ledge down in the radiator itself. If there is a crack in it, the worst that would happen is the possibility that when the pressure in your fadiator exceeds the 4 lb cap, the coolant will not only have the option to escape via the overflow tube, but it MIGHT also escape between the cap and the edge of the radiator where the brass disc is mounted.

The point being....the brass disc has nothing to do with actual SEAL the gasket provides between radiator neck and cap. If it is not what seals the system, then it is not what maintains the pressure in the system"

from http://www.g503.com/forums/viewtopic.php?f=4&t=187068 (saved me a lot of typing).

Another quick test is simply pressurize the coolant system to 4 PSI (that is below the cap lift set point) and let if sit. Walk away for 20-30 minutes and if its still at 4 psi then you have no leaks, (but your radiator may sill need a cleaning).

There are several pipe plugs next to the water pump to attach a nipple with a gauge and valve... think of it as a leakdown test for the radiator.

You can also check the head gasket and block for cracks the same way.. but just use more pressure, about 100psi through the spark plug hole. If you see bubbles in the radiator then you have a leak, and the last cylinder you pressurized is the culprit. REMEMBER you need to let it sit for 20-30 minutes per cylinder.

Also, drain your oil. If there is coolant in the oil then you KNOW you have the check for cracks in the block/head gasket.

Don't start unbolting things till you know what you are looking for, otherwise, well, you won't know what TO look for.

still think u need to look at your car/truck thermostat!!

I do think this is how the original rad caps are made, without any kind of gasket except for the brass / copper flange part of the rad cap which sits on the top lip of the rad filler cap hole. This is how mine is and had no problems with using water or over heating over the past 15 years of long trips at 40 ish MPH, dual carriageways ect. to France and loaded.

Also regarding the filling of the rad, there is a baffle over the top hose inlet to the rad so you cant see the water level through the filler cap, all I do is top it up till you can see it then put cap on and use it, excess water is then pushed out through the overflow and then it stops once its at the correct level. Check every now and then and that's about it.

Hi Cubed

The penny has dropped for me, after a posting on the other thread. The gasket sits in the neck of the rad, not on the cap it self, which is why of course I couldn't see anything (chuckle). :blush: :n00b:

so does that gasket you have then fit in the neck of the rad and also does the inner hole of that gasket fit over the bit of the rad cap which fits into the top of the rad !!!!

Lets have some more pics.