1953 Radiator Cap

[Geekay]

The Fargo is now running well aftre I cleaned the carby and replaced some gaskets, so I thought I should pay attention to the cooling system.

 

I have previously removed the water pump and thermostat and flushed the block and radiator as best I could with water and air pressure.

 

The radiator cap does not have the usual pressure spring that I am used to seeing so thought it must be missing.

 

However, just read the forum Tech Info that says:

 

" P15 and D24s use a non-pressure cooling system. If you use a pressurized cap you will probably damage the radiator as it is not built to handle the higher pressure and it may push the water temperatures up"

 

Really!! A non pressurised system. What the....????

 

So the cap just sits there loosely???  I gather when the water gets hot and expands some will be pushed out under the cap?

 

The temp gauge indicates idling temp below 170 degrees, and if I take off the radiator cap and stick in my finger the water is hottish (that's somewhere between warm and hot  ) so i assume the cooling system is working (the fan is turning).

 

 

[_shel_ny]

P15, D24 was a non-pressurized system. Later car started using a pressurized system. (4 lb) Trucks likely did as well. Someone with a truck parts book may be able to expand upon that.

[Jeff Balazs]

Yep! No pressure required.

 

Jeff

[Desotodav]

170 is a good running temp GK. You will find that our climate here in Oz will see your temp climb up to around 190 on a really hot day. I had a lot of issues with rust flakes clogging the system not long after getting the 52 truck on the road, so I found it was best to flush the cooling system at regular intervals until the sediment dispersed. I now find that the 52 truck runs pretty much around 175 degrees most of the time. I installed a 'hi-flow' thermostat after chatting with my radiator man. There is a mistaken belief here in Oz that we do not require thermostats here due to our mild climate, but nothing could be further from the truth as the thermostat slows the water flow rate allowing it time to cool in the radiator.

You are making good progress. Keep up the good work my friend!

Edited February 4, 2015 by Desotodav

[NiftyFifty]

Been running without a t-stat since I blew my head gasket after my rebuild, the lack of bypass overheated when it stuck, so I removed it and 3 full seasons without issue. Even in town when it's 30 cel above In traffic, it's never more then about 190F. If I did put one back in, I'd drill a 1/8" hole through it to keep some flow going. As for the cap, never hurts to put a new one on regardless of it not being pressurized.

[Jerry Roberts]

" So the cap just sits there loosely ? "    Well , I would snug it up a little so that it doesn't fall off . Take a look at your overflow tube , on a non-pressurized system it should be vented to the atmosphere at all times . I really like my non-pressurized system , it runs at 160 all of the time , once warmed up . 

[MBF]

On these vehicles with the stock powertrains, I look at the radiator cap as a nothing more than a cover to the radiator spout to check coolent levels, and to keep the coolent in the system.   Simple is good by me.   Mike

[Jeff Balazs]

Geekay;

I had similar experience as Davin with my truck. Even though I flushed the living daylights out of my engine and put a fresh radiator there was a fair amount of rust flakes in the system. It took several more flushings to get the system clean. And yes you should have a thermostat in place. You can either run a 160 which should result in an average running temp of around 175 or you can run a 180. The advantage of the 180 thermostat is that less condensate will be formed in the crankcase as a result of the slightly higher operating temp. You can combine this with a proper PCV system and that old nemisis of these engines sludge build up is dramatically reduced. You will hear many pros and cons on PCV installations but I will tell you right here and now that they work and your engine will actually run better once you have the proper set up.

 

Jeff

[NiftyFifty]

My 218 had no t-stat, my 230 didn't either(came in my parts truck) , and my 251 came without one in it....I'm thinking they can be more of an issue then a benefit in these old engines. I'll be running dual 9" fans this summer, I think I'm going to keep things the same...Id prefer not to do a head gasket once a year, or risk warping my head. My truck runs excellent, I could ask for anything else out of it.

[Jeff Balazs]

My 218 had no t-stat, my 230 didn't either(came in my parts truck) , and my 251 came without one in it....I'm thinking they can be more of an issue then a benefit in these old engines. I'll be running dual 9" fans this summer, I think I'm going to keep things the same...Id prefer not to do a head gasket once a year, or risk warping my head. My truck runs excellent, I could ask for anything else out of it.

Interesting ? So if I understand what you had happen.... a stuck closed thermostat caused a blown head gasket? Was it actually a faulty new thermostat ? Or was it blocked with rust particles from the cooling system once it had run for a while. I can certainly see the latter happening as there was quite a build up of it sitting on top of the thermostat in my truck the first few times I re flushed the system after initial run in. It was definitely causing my truck to run warmer than it should...or does now. Getting the cooling system free of these rust particles on one of these engines that has sat for a while is a real chore. This is one of those things that we all need to keep a very close eye on.

 

Without a thermostat there is no real way to actually regulate the operating temperature your engine see's. I can't say how that works in your case but it definitely would not cut it in this climate or I imagine in Australia which is similar to here. It surely runs counter to conventional wisdom regarding automotive cooling systems and the importance of regulating operating temperatures.

 

Jeff

[olddodgeguy]

The reason for pressurized systems was to raise the boiling point of water.  Wasn't needed back in the day!  A thermostat is used so the engine can come up to operating temp sooner.  Different temps are for different purposes.  Mike

[Don Coatney]

There are many problems that can cause head gasket failure. Warped head, uneven block, incorrect torque sequence, failure to re-torque after the first heat cycle, and maybe over heating but that one is difficult to prove. In my opinion use of a thermostat per the factory design is the way to go. As has been mentioned engine operating temperature is controlled by the thermostat. And in my opinion the engine should be operated in the 180-190 degree range. At this temperature the condensation in the crankcase will be lower adding to the life of engine wear parts due to less oil contamination. As I said this is just my opinion. If using no thermostat works for others that is fine with me.

[55 Fargo]

My 218 had no t-stat, my 230 didn't either(came in my parts truck) , and my 251 came without one in it....I'm thinking they can be more of an issue then a benefit in these old engines. I'll be running dual 9" fans this summer, I think I'm going to keep things the same...Id prefer not to do a head gasket once a year, or risk warping my head. My truck runs excellent, I could ask for anything else out of it.

Being were from the same neck of the woods, funny how our experience differs. I have had about 6-8 of these engines, never found one without a t/stat.

I have run them with  and tried without, much prefer them in, slows the flow down for far more efficient cooling. If a rad has poor flow or partially plugged passages, having no t/stat may not make any difference as the flow is much slower anyway.

Although it gets good and hot here , we do not experience as much heat as they do in the south

[55 Fargo]

The Fargo is now running well aftre I cleaned the carby and replaced some gaskets, so I thought I should pay attention to the cooling system.

 

I have previously removed the water pump and thermostat and flushed the block and radiator as best I could with water and air pressure.

 

The radiator cap does not have the usual pressure spring that I am used to seeing so thought it must be missing.

 

However, just read the forum Tech Info that says:

 

" P15 and D24s use a non-pressure cooling system. If you use a pressurized cap you will probably damage the radiator as it is not built to handle the higher pressure and it may push the water temperatures up"

 

Really!! A non pressurised system. What the....????

 

So the cap just sits there loosely???  I gather when the water gets hot and expands some will be pushed out under the cap?

 

The temp gauge indicates idling temp below 170 degrees, and if I take off the radiator cap and stick in my finger the water is hottish (that's somewhere between warm and hot  ) so i assume the cooling system is working (the fan is turning).

Most Mopar rads 1950 and later were designed for a pressure system, the rad will have a seat that allows a modern pressurized rad cap to seal against, usually with an overflow tube in the neck.

The non-pressurized system will have a cap that is just that a cap, there will be a blow off over flow tub at the highest point on the top rad tank.

Go buy yourself a 4 lb rad cap, and do not try anything over 7lb, try and stick with the 4 lb cap....PS, unless you know this engine block is pretty darn clean, pull the water distribution tub, and the bottom frost plugs, and flush this old cruddy/rusty block clean, then button here up, and run water a few cycles flush and repeat.

You can even add a cup of Electrosol dishwasher detergent to the water, run and get things running warm, drain add water run and flush.

Then when things are clean, add new fresh antifreeze.....

[NiftyFifty]

Interesting ? So if I understand what you had happen.... a stuck closed thermostat caused a blown head gasket? Was it actually a faulty new thermostat ? Or was it blocked with rust particles from the cooling system once it had run for a while. I can certainly see the latter happening as there was quite a build up of it sitting on top of the thermostat in my truck the first few times I re flushed the system after initial run in. It was definitely causing my truck to run warmer than it should...or does now. Getting the cooling system free of these rust particles on one of these engines that has sat for a while is a real chore. This is one of those things that we all need to keep a very close eye on.

 

Without a thermostat there is no real way to actually regulate the operating temperature your engine see's. I can't say how that works in your case but it definitely would not cut it in this climate or I imagine in Australia which is similar to here. It surely runs counter to conventional wisdom regarding automotive cooling systems and the importance of regulating operating temperatures.

 

Jeff

It was faulty, my block was clean as a whistle, it had the tube pulled and was dunked when it went in for machining work and new cam bearings, rad and core were also flushed at the rad shop for some repairs... It just plain stuck and I was on the highway and by the time we got back home a few miles it started burning white. I could see in an extreme hot climate, that is a different story...here in Canada where I am, works just peachy

[NiftyFifty]

Most Mopar rads 1950 and later were designed for a pressure system, the rad will have a seat that allows a modern pressurized rad cap to seal against, usually with an overflow tube in the neck.

The non-pressurized system will have a cap that is just that a cap, there will be a blow off over flow tub at the highest point on the top rad tank.

Go buy yourself a 4 lb rad cap, and do not try anything over 7lb, try and stick with the 4 lb cap....PS, unless you know this engine block is pretty darn clean, pull the water distribution tub, and the bottom frost plugs, and flush this old cruddy/rusty block clean, then button here up, and run water a few cycles flush and repeat.

You can even add a cup of Electrosol dishwasher detergent to the water, run and get things running warm, drain add water run and flush.

Then when things are clean, add new fresh antifreeze.....

Not sure they were ever meant for pressure, my 50 rad was great the first few runs with the original motor, then leaked like a cauldron because I was sold the wrong cap at Napa and it was for a pressurized system, at that time I didn't know the difference. Might as well have put a bomb in it..lol. I'm running a 4lb cap now that the rad shop sold me when they flushed my 51 rad that I put in...works great...I wouldn't risk a 7lb cap either

[55 Fargo]

Not sure they were ever meant for pressure, my 50 rad was great the first few runs with the original motor, then leaked like a cauldron because I was sold the wrong cap at Napa and it was for a pressurized system, at that time I didn't know the difference. Might as well have put a bomb in it..lol. I'm running a 4lb cap now that the rad shop sold me when they flushed my 51 rad that I put in...works great...I wouldn't risk a 7lb cap either

My reference is to a modern at that time pressurized cooling system, starting around 1950-51, and well not a 15 lb cap, I have used 4 and even 7 without negative effects. I am currently using a 4 lb cap.

[55 Fargo]

Just for reference sake, any modern cap that is used on a non-pressurized rad, will not pressurize. Those rads have a vent/overflow tube at the high point of the rad, above the height of the cap, thus not allowing the rad and/or cooling system to pressurize..... just sayin

[IanT_Qld]

Regarding sludge build up - there is a little stop-cock/tap on the left side of the block, i regularly open this and let out about 1/2 litre of brown coolant before the clean green coolant comes through. Just remember to top the radiator back up. yes to thermostat, and a non-spring cap.

[NiftyFifty]

Just for reference sake, any modern cap that is used on a non-pressurized rad, will not pressurize. Those rads have a vent/overflow tube at the high point of the rad, above the height of the cap, thus not allowing the rad and/or cooling system to pressurize..... just sayin

Not on any I've seen? Not even a later pressurized system does that, it's the cap that allows the pressure to bleed off into the overflow. A pressurized cap on these non systems blocks off that tube and does not allow the coolant to over flow, hence the issue I had...as you can see in the picture of a 51 rad the tube is above the place the spring/seal seats to the rad.

[55 Fargo]

Not on any I've seen? Not even a later pressurized system does that, it's the cap that allows the pressure to bleed off into the overflow. A pressurized cap on these non systems blocks off that tube and does not allow the coolant to over flow, hence the issue I had...as you can see in the picture of a 51 rad the tube is above the place the spring/seal seats to the rad.

What you have pictured is a pressurized style rad, where the over flow is in the throat of the cap tube.

Have you not seen a non-pressure style rad that pre-date these newer designed rads....geesh

[NiftyFifty]

That is the stock rad from my 1951 NON PRESSURIZED truck, sitting in my 50, my 50 rad didn't have whatever extra port the one you have pictured either, and even the one pictured shows a tube in the neck that would be above the line. Not everyone has the same rad you possess, and telling guys it doesn't matter is incorrect information

[NiftyFifty]

FYI on stock rad photo from the 51-53 parts book showing only a overflow tube in the filler neck

[55 Fargo]

That is the stock rad from my 1951 NON PRESSURIZED truck, sitting in my 50, my 50 rad didn't have whatever extra port the one you have pictured either, and even the one pictured shows a tube in the neck that would be above the line. Not everyone has the same rad you possess, and telling guys it doesn't matter is incorrect information

So let me get this, your rad allows a cap to seat in, and when enough pressure may build it would lift the plunger and release pressure. Or you could use a non-pressure cap, and if it boils, the coolant just blows out the overflow tube, in the filler neck.

 

FYI on stock rad photo from the 51-53 parts book showing only a overflow tube in the filler neck

Yup looks like the first pressurized cooling system rad to me, BTW my 55 Fargo truck has a pressurized cooling system, so the rad in the picture is a point of reference, but had the identical type in my 1947 Chrysler. In fact I have a spare in the shed, will take a pic of it tomorrow and post.

[NiftyFifty]

So let me get this, your rad allows a cap to seat in, and when enough pressure may build it would lift the plunger and release pressure. Or you could use a non-pressure cap, and if it boils, the coolant just blows out the overflow tube, in the filler neck.

Yup looks like the first pressurized cooling system rad to me, BTW my 55 Fargo truck has a pressurized cooling system, so the rad in the picture is a point of reference, but had the identical type in my 1947 Chrysler. In fact I have a spare in the shed, will take a pic of it tomorrow and post.

Exactly, but in this case if a pressurized cap is used the rad or whatever weak link in the system will blow. The trucks were not designed for pressure regardless of how the overflow tube is placed...with the stock cap, no damage should occur

The rad in your picture definitely would not work in a pressurized system, but I have yet to ever see one like it in one of these trucks 48-53 which is in the years of the OP. Chrysler may have used a similar rad later on when they used pressure systems, but internals or production methods may have changed once they went to that system.

Edited February 6, 2015 by 4mula-dlx