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Is your exhaust manifold heat control valve set properly? Page 198 of the TM9-801 A free copy is available at: http://www.tm9-801.com/tm9-801/index.php

Snippet from AR850-5 http://www.cckw.org/pdf/ar850-5_2_15_05_2.pdf

Most auto parts stores will have gasket material... it my be worthwhile to cut one out yourself that is the proper size. Match the thickness (is say thicker is better than thinner) and use a compass and razor. Other option would be to put the time in to research what other radiator caps fit the CCKW radiator and buy the gasket from that part. Then post here so we know Get well soon.

I am having trouble getting a free copy of the FEB1945 AR 850 But if we look at the [h=1]"Standard catalog of U.S. military vehicles By David Doyle"[/h]page 492: 15Feb45 blue drab out, white in. It does say that existing blue drab paint was to be used, but I don't recall that in the AR850's text.

I found an Ar850-10 that states that the change from BLUE to WHITE registration numbers were to be applied by the manufacturer. This is a 15 Feb 1945 issue of AR 850-10. There March 45 issue of Army Motors cites this also. I've gotten all sorts of round-about answers like the AR is wrong, not applicable, wasn't enforced, etc etc etc. Most people read off the 1942 AR850 for markings.. and leave it with that (most likely because its available for free).

I'd like to pass this on, and if I'm incorrect please let me know. Its seems to be commonly cited that BLUE DRAB was the factory registration number paint, and any white registration numbers were the original registration number repainted after a repair or repaint (approx every two years). But AR850-5 dated 15Feb 45 directs that factories STOP using blue drab, and switch to WHITE. So any vehicle accepted after the date the AR was implemented would have have WHITE registration numbers FROM THE FACTORY. The AR850 also directs that ALL vehicles have the registration number paint WHITE by AUGUST 15th, 1945 (who knew that was going to be VJ day? So with the exception of some very early 45 vehicles, all 1945 models should have white registration numbers.

I may be a bit more of a perfectionist, but I would recommend that you take that gasket out, place a rag below the lip (to prevent chunks from blocking a rad. tube) and run a wire cupped wheel in the neck to get rid of that rust/scale. The scale/buildup may still prevent the gasket from seating on the lip properly. may work fine as is, though. From talking to a few other people, I think the missing gasket is highly prevalent.

I'm going to guess that A LOT of CCKWs are rolling around with low water levels because that gasket is missing. Mine didn't have one and it ran fine.. and to be honest I never looked for it because I never had a temp problem. I would also guess that the infrequent operation saved it from any real damage. If it was a daily driver then the water would have boiled out completely and made it known that something was up with the cooling system.

Apologies if I came off to harsh, but please understand that sometimes what I read doesn't really translate well... or I miss some of the nuances of the post. I am very surprised (if I read it correctly) that you can get a CCKW towed for 30GBP. That seems like it would not even cover the diesel fuel cost to drive to a disabled CCKW.

I you have that much free rust in your cooling system then whats in the radiator tubes? The cylinder jacket? For the gentlemen that are dismissing a dirty cooling system, or WORSE, saying its NORMAL please stop, stop right now. Its obvious that at some point the coolant was simply water, or the antifreeze was so old that its lost its properties and allowed the cast iron to rust. The rust is turns to sediment which clogs the passages in the block and radiator tubes. If you think its normal, then you really need to read up on PROPER coolant maintenance. My 42 GPW, 43 GMC and 66 M35A2's innards look like the day they were cast. A proper flush (nothing you buy off the shelf at a store is worth anything.. you need professional chemicals and a air agitation system) is needed. Your innards should look like cast iron (grayish). You may go another month, year, or decade with the condition its in now.. there is no way to tell. But you hare having cooling issues now, might as well fix it and be done with it. Not sure what it costs to tow a CCKW in the UK, but I've talked to several heavy tow tuck company's in the area (I work in distribution, so having a tow driver on the yard is not an uncommon occurrence) and none of them would even start up the wrecker for less than $500, plus mileage (Approx $15 per mile... BOTH WAYS for a 15,000 lb cckw). So a few quid for a flush, pressure check and refill is the cheaper of the two options, in my book.

Um... your cooling system looks HORRIBLE. None of the that rust should be there. You DO have the gakset... its the red thing with the lip pressed into it. Look at the hole for the overflow tube... you can see the edige of the gasket there. Compare to mine... I have no gasket I wouldn't put parts in or troubleshoot anything until you get that radiator cleaned. You may want to get the ENTIRE cooling system flushed. That's bad.. really, really bad. Like its been run on plain water, not anti-freeze. No rust! And no gasket either

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.

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.

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.

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.

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.

Just thought I'd clean this tread up and dispell some myths: T-stats have vent holes, no way air/vacuum can be trapped: Does a CCKW t-stat FAIL to the open position (by design, like modern ones) or it simply can break and randomly be open or shut?

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:

Get modern water temp gauge and plug that into the block. The bourdon tube in the temp gauge may be out of adjustment and require re-bending to get the gauge to show the proper temp. Then engine temp should only be 180-ish. A working t-stat starts to open at 160. If you think the t-stat is stuck open (that's a very rare failure mode... they typically fail to open and overheat the engine) a simple test: Engine cold. Remove radiator cap Start engine If cold engine shows radiator coolant moving (you can easily see it being circulated) then the t-stat is open when it should not be. Are you sure you have a t-stat installed? DO any of the radiator hoses get HOT when at fast idle? It should not take more than 10-20 minutes to get the coolant to 180F I recommend cardboard!!!!

Where are these air tight t-stats coming from? How you creating a vacuum in a pressurized fluid? The t-stat is BELOW the full level of the radiator. The t-stat is not air tight. How are you creating these air pockets/vacuum chambers? Cardboard? Are you ready for the TM cite? TM9-801 April 1944 page 221: Sorry, I don't have a part number for the card board. :-D:cool2:

What old trick says fill an engine via the t-stat? T-stat valves are not air tight. If you are getting a pressure differential across a t-stat then its probably clogged or rusted shut. No US MV that I know of says anything other than a proper coolant refill is done by filling the radiator till coolant is visible, run the engine and refill. Unless there are some wacky British vehicles (and after owning a MG Midget I can attest to some odd mechanical arrangements on British cars) that you need to fill via the t-stat, while facing east, standing on the left foot and pouring with the left hand (hahahaha I'm kidding) hoses are best left attached and sealed. Feel free to add coolant anyway you like... its always interesting to hear other ways of doing things.

You will be very low on coolant if you only fill as you state. About 2-3 liters low. Fill the radiator till you see fluid. Any excess will blow out the cap as overflow. The engine will find its own level. How is this vacuum forming? The cooling system is not air tight.. and vacuum will fill with fluid and any excess pressure will vent.

The t-stat is significantly below the radiator cap and the full level of the radiator. Also, there is a built in bypass so water will always circulate and prevent any sort of lock.

Your mechanic must be a rich man! To be honest I really didn't let the engine warm up fully either. Even so, cooling systems can be overcome by nothing more than it being to cold out. When we get a stretch of < 20F weather (about -10C) its not uncommon to see a lot of cardboard over radiators. So don't be so fast to rip your engine apart before you have a very good idea what the the problem is.

Do you have any portion of the radiator blocked off? While 41F (5C) is not arctic, when traveling at speed 30-35MPH (60-ish kph) you are down to 29F (-2C) and for a short trip that will suck the BTU out of the engine (I bet the block never got warm to the touch) After work last night my car home (after a 7 mile drive at 30-50mph) never showed a temp on gauge and the outside air temp was 25F (10F or -12C wind chill).. and my thermostat is fine. The reason why you showed a temp when off is because the water was not moving and there was nowhere for the heat to go.... so it actually did get the temp bulb warm enough to register on the gauge. Your t-stat could be stuck open... but before you mess with coolant and hoses block off the radiator with cardboard. Start the engine and let it fast idle (using the hand throttle) till you get normal temps (180ish). Take off the cardboard and go for a spin. If the engine cannot hold operating temp then you know the tstat is stuck open. If the temp stays 180ish then its working.. you might see the gauge swing abruptly as the t-stat opens for the first time... but after that the t-stat will open partially (it generally never completely closes... it finds a happy 'semi open' state).