Unhappy with pressurised radiator

woofa.express

woofa.express

Well-known member
I bought and fitted new radiators to both my 28 tourer and 28 ute. The tourer a normal ambient pressure radiator and the ute a 4 psi pressurised radiator. At 45mph the normal will operate normally and the pressurised one will jettison water and boil.
Question. Has any user found this problem or am I Robinson Crusoe?
I think I’ll take it to a radiator specialist and ask to have it modified back to normal. Question. Does anyone have a view on this?
 
Woofa, I have a pressurized radiator that I will send to you if you want (you have to pay the freight). I was never very happy with it. It seemed to spit out coolant on a regular basis. To be fair it has some leaks where it hit the fan and there were some issues with a head gasket leak. I tried a 90 year old stock radiator but it did not cool well enough for my hopped up Fordor so I ended up buying a Bergs radiator which I am very happy with. It is atmospheric so the radiator cap is in the correct place.
 
Have you tried switching radiators?, if the problem moves with the radiator you will know what the cause is
 
Any amount of head gasket leak of combustion gas into the waterjacket connected to a pressurized radiator and you are going to have problems. An atmospheric radiator will take a bit of leaking and pass it out the overflow tube.
Good Day!
 
Red asked if there was a thermostat installed. My thermostat caused the coolant flow to be erratic. The engine would get really hot then the thermostat would open and hot coolant would flow to the radiator where I would get a discharge of coolant. Then it would shut and the cycle would repeat. Originally the thermostat had one small hole that was used to clear air while filling the radiator. The thermostat lives in the outflow hose just above the gooseneck.

I drilled 6 quarter-inch holes in the flange of the thermostat and that works better. For one thing the coolant has more flow all the time so the thermostat is more accurately sensing the coolant temperature. The flow at lower temperatures makes the temperature in the engine more even. When it gets hot the thermostat opens and the combined flow from the holes and thermostat cools better. When the temperature of the coolant at the gooseneck is 140 degrees the temperature at the head is 170.
 
6 1/4 inch holes...................you may as well take the t/stat out in my opinion.
Are you sure it's a 4 psi cap?? How many rows and fins per inch??
As others have stated, install a recovery tank and get back to us.
Paul in CT
 
.I don't think a non-pressured radiator will suck the water back in,it never makes much pressure and when it cools it can't pull it back in.I could be wrong but my overflow would fill up but never go down,it's on a slip bracket ,just pull it off and pour it back in through the open cap.
 
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I didn't think you needed more than 2 1/18 inch holes drilled in the tstat flange. 6 might be overdoing it.

But, then again, I used to have a vet with only 2 holes in the tstat and the symptoms were exactly the same as nk describes. So..........
 
Thankyou all for your input.

To answer the questions you put.

Yes, I do have an overflow. Purchased from Snyders, a generic type, long chrome cylinder, looks good but holds only a small quantity.

No thermostat installed.

Swap radiators. Sounds like a good idea. I’ll make that my last resort.

Thankyou nkaminar for your offer of a pressurised radiator, but no. Following this I am suspect of them.

Loosen the cap. I don’t know. It overflow through the expansion tank so I would expect that overflow simply to be transferred to the cap.

I do have a filter in the radiator return hose. A tea strainer which is effective. I’ve checked that in the past and found it to be clear.

The vehicle is waiting to be upgraded to a 12v and blinking indicators which is to be modified by an autolec. It has a temp gauge mounted and yet to be connected. That should be informative.

Question. What are the give away signs of compression bypass or head gasket failure which may cause this radiator overflow.

I’ll check the return hose filter again, wait till I get the 12v conversion and temp gauge connected then I’ll give you all a report. Never the less I am tempted to modify radiator to non pressurised.
 
One way is to take off belt, fill radiator to top and crank engine with ignition off, if it pushes water out there is a combustion chamber leak, then start it with belt off and see if bubbles come or water pushed out, but after 30 seconds or so the water will start getting warmer and expand some, look for bubbles in radiator neck, this is not always exact science, another way is to submerge overflow hose in clear jar (belt on)with clean water in it and watch for bubbles production--- in the block and head have a lot of rust scale there may be heat conduction barrier and micro bubble from preboiling under the rust
 
Kurt in NJ said:
One way is to take off belt, fill radiator to top and crank engine with ignition off, if it pushes water out there is a combustion chamber leak, then start it with belt off and see if bubbles come or water pushed out, but after 30 seconds or so the water will start getting warmer and expand some, look for bubbles in radiator neck, this is not always exact science, another way is to submerge overflow hose in clear jar (belt on)with clean water in it and watch for bubbles production--- in the block and head have a lot of rust scale there may be heat conduction barrier and micro bubble from preboiling under the rust
Click to expand...

Now that's logical and makes sense. I'll try that and thankyou Kurt.
 
The car doesn’t care or know the difference between a pressurized and non pressurized radiator. Putting a pressurized radiator on is only exasperating an existing issue. Lots of helpful suggestions above that will help you get to the real issue.

I’d remove the filter. Modern cars don’t need them, and again, a filter is only addressing an issue that needs to be addressed anyways.
 
Let it find its own level once and see what happens
Is it actually overheating or just puking coolant out every time because u are filling rad to the top?????


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The radiator boils. It is not a case of filling it to the top and loosing a quantity. Some good suggestions on checking if there is a head gasket leak. Thankyou all who have contributed your findings. gary
 
I have a 2.5 psi radiator cap on adaptor I bought on a trip to Texas. It sits down by the horn wiring and is on the overflow tube. There is an overflo tank on the radiator locating rods and I use a homemade gasket to seal the filler lid.It works beautifully and I have had no heating issues in all the years it has been on my roadster. Denny Specker sold them at Barstow, CA and a fellow in a pickup was going to turn back from our trip just as we were getting started because he had so much water being pushed out by his water pump. This little device saved the day and he and his trick made it to Addison and back without any heating problems. I wish I had bought a dozen of them.
 
daveymc29 said:
I have a 2.5 psi radiator cap on adaptor I bought on a trip to Texas. It sits down by the horn wiring and is on the overflow tube. There is an overflo tank on the radiator locating rods and I use a homemade gasket to seal the filler lid.It works beautifully and I have had no heating issues in all the years it has been on my roadster. Denny Specker sold them at Barstow, CA and a fellow in a pickup was going to turn back from our trip just as we were getting started because he had so much water being pushed out by his water pump. This little device saved the day and he and his trick made it to Addison and back without any heating problems. I wish I had bought a dozen of them.
Click to expand...

A picture or 2 would be nice.
 
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