Radiator question

S

ssrcobra

Member
So I had coolant coming out of the head from porosity of the casting. Everyone told me to buy BarsLeak and use that to fix the problem. It was against my judgment to do this but I did and it seems like it worked.

So now I have new question the radiator cap??? It not like its a pressure cap is this correct? what happens if there so much expansion and coolant has to come out, how does the system lose the coolant? Should there be a gasket on the cap? What about the pumps Skip Haney rebuilds, should I just get them done now so I don't have to screw around with it later?

HELP
Thanks
Tom
Oh we are talking about a 1935
 
The radiator has an overflow tube built in. Skip Haney also makes a pressure valve to install on the overflow tube. This is the best way to pressurize the older type radiators prior to the 8BA era. It's only a 3 pounder but the older radiators won't hold much more than that if any.
 
rotorwrench said:
The radiator has an overflow tube built in. Skip Haney also makes a pressure valve to install on the overflow tube. This is the best way to pressurize the older type radiators prior to the 8BA era. It's only a 3 pounder but the older radiators won't hold much more than that if any.
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I think the cores will hold?...I've seen a few swollen tanks though...had always assumed by running a higher pressure cap.

Just wondering.
 
rotorwrench said:
The radiator has an overflow tube built in. Skip Haney also makes a pressure valve to install on the overflow tube. This is the best way to pressurize the older type radiators prior to the 8BA era. It's only a 3 pounder but the older radiators won't hold much more than that if any.
Click to expand...

As Roto states - your stock radiator should have an overflow tube - so should look like this (picture) with the overflow tube allowing for expansion on an overfill situation. Double click on picture to enlarge
 

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So, if someone could further explain the system, I would appreciate it.
It sounds like the radiator cap just seals the top of the radiator, but the overflow tube is free flowing, and not controlled by the cap, as in a pressurized system.
So then, the theory behind the Skip Haney pressure valve is to add this to the overflow tube to 'seal' the system to add a small amount of pressure.. nice idea!!
If someone could enlighten me, I would appreciate it.
By the way, if it matters to the design, I have an overflow tube that goes down the side of the radiator. When I bought my truck a few months ago, someone had added a rubber tube to the end, and stuck in in a gallon jug under the hood.
I have seen the small cylindrical overflow tanks, and it seems to me that on a free flow system, that would not be adequate.
 
I have same problem with my 53 vic. I have a 7.5 lb cap on it but it overflowed last night during a test run in the shop last night. What cap should I have on it?
 
Modern radiators are designed for higher pressures but the old ones aren't. It was just a way to increase the temperature point where the coolant would start to boil so the system could take more heat. If the motor is getting hot, it will start to push coolant out of the tank due to excessive expansion and or boiling up steam. Non presurized systems tend to barf out coolant whenever we are pushing them too hard such as going too fast, pulling heavy loads, or climbing a lot of steep hills. Pressurized systems hold there mud a lot better but can still occasionally be pushed too hard if the coolant level is low or there is some blockage starting to build up in the coolant passages.

If an 8BA is pushing coolant past a 7.5# cap then it is either overheating or it has compression gasses leaking into the coolant system which will also cause overheatinig due to the disruption of the coolant flow. Water seeping out anywhere will also allow air to seep in under flow so that will cause higher than normal temperatures too. Coolant full of air, combustion gasses, or boiling to steam won't cool much.
 
I had it up to 208 degrees on one side and 204 on the other side. I have a stock 3 blade fan on it now, but I do have a truck fan on the shelf. I think it is a 5 blade? No stats in it yet but figure to get a set today from Napa. I am guessing 180 would be OK?
 
If it is going that high without thermostats I would guess there are some issues with the cooling that a pressure cap is not going to solve.
 
I just talked to Mike at Antique auto. He said the cap should be 4 lb but 7.5 was ok. He suggested I put 175 stats in. That also slows down the water flow in radiator.
Is there room for the truck fan and is it a direct replacement?
 
Your radiator might need to be rodded out due to blockage. Those temps aren't enough alone to get a 7.5 # cap to purge. You should be able to run the engine with the cap off while it is warming up without any coolant purging. If it purges with the cap off, I'd start looking at the radiator core or for blown head gasket, loose head bolts, or something of that nature.
 
Make sure the cap is seating properly in the neck. Some of the new caps are slightly oversize and don't seal off the radiator neck allowing coolant to be pushed out of the overflow.
 
rotorwrench said:
Your radiator might need to be rodded out due to blockage. Those temps aren't enough alone to get a 7.5 # cap to purge. You should be able to run the engine with the cap off while it is warming up without any coolant purging. If it purges with the cap off, I'd start looking at the radiator core or for blown head gasket, loose head bolts, or something of that nature.
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I had the radiator rodded out before installing. I installed new gaskets about 4 hrs running time and no water in oil. Havent driven it yet since restoring it.
I just went to town and bought tstats (180)s.
I put an electric fan in front of radiator last night and it did cool better.
The engine runs so sweet I am hoping not a head gasket
 
TJ said:
Make sure the cap is seating properly in the neck. Some of the new caps are slightly oversize and don't seal off the radiator neck allowing coolant to be pushed out of the overflow.
Click to expand...

Now that is a good thought, I"ll check that
 
old radiator cores loose the connection between the tubes and fins because of corrosion over the years and because of that the fins do not conduct heat away as they should. Usually a new core is the answer after you have determined there are on compression leaks and someone has not sawed half the paddles off your water pumps.
 
My son went to my parts car and brought in another cap that was completely different than the one I had on it. I will try it over the weekend.
jimTN, I also have brand new water pumps on it. I am anxious to try it with the different cap.
 
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