Possible Radiator Problem???
- Thread starter loubob
- Start date
Bill G
Well-known member
28-29 caps are both threaded and are, indeed, identical except for one is vented and the other is solid. I am not sure about 30/31 twist-on's. When I first got my car, someone had reversed mine. Radiator was loosing water from the cap itself. The cap on the gas tank was drilled with a hole and a small nut & bolt inserted. This created a vent, of sorts.
It should be noted that if you use a radiator cap on the gas tank, there is not normally a vent. All things being equal, your car won't run very long because the lack of a vent will create a vacuum in the tank, and you would have to get out and open the cap to let it vent before going on your way.
George Miller
Well-known member
head gasket, or slow timing, or to lean a mixture will do it.
Guys I had the same problem ! i took the radiator to a radiator shop & bad it boiled out & repaired, but it did no god. they were afraid to try to rod it out for fear of destroying it. I put it back on the car & had the same problem all over again! would loose coolant on a long hill or a hot day. turned out that the radiator was about half plugged & the water pump was just simply moving more water than the radiator could handle. I broke down & bought a new aluminum radiator & problem solved.
Synchro909
Well-known member
I'm afraid this is a common myth. It is not possible for the pump to move more water than the radiator can handle because the ONLY place the pump can get water is from the bottom of the radiator (via the engine) I suspect that when your radiator was tossing coolant out, the coolant was boiling, thus increasing its volume.
Whatever, it is fixed now so enjoy.
30 Closed Cab PU
Well-known member
Not agreeing, not disagreeing, just need more explanation.
1.5 gals in the radiator, 1.5 gals in the motor/hoses. If the water pump pumps more water than can flow through the radiator, why can the pump not continue to pump/draw the 1.5 gals from the block causing pressure, pumping water out the overflow and/or an ill sealed radiator cap?
Agree that it could be boiling. Overheating coolant caused by head gasket leak into coolant raising the coolant temp. Is it also possible a bad head gasket cylinder leak to the coolant passages cause the pistons to add pressure into the coolant?
Synchro909
Well-known member
Closed Cab, Let me try to answer that question by asking another: What is going to replace the water taken from the block?
eagle
Well-known member
Exactly. When the radiator is partially plugged, the lowest pressure of the whole system is in the engine block. Lower pressure = lower boiling point = coolant flashing to steam = expansion of flashed coolant by 1700 times the volume = coolant pushing out anywhere it can. Fix the radiator, fix the problem. Reduce the water pump volume = bandaid fix that may get you by but not indefinitely.
30 Closed Cab PU
Well-known member
Thanks for your response, excellent question. I had to think about this overnight and think I have come up with a proposed theory/explanation that works for me. What was confusing for me is the A cooling system is a closed loop, but not totally sealed system (overflow tube).
Flow is restricted via a clogged radiator. The pump works harder trying to draw more coolant out of the block and pumping/pushing it into the top of the radiator. This would create pressure in the top of the radiator, lower pressure in the bottom of the radiator.
My aha moment was when I realized the Model A water pump is low pressure vane style pump? The vanes do not have the feature of vane seals to the impeller cavity to create higher pressure. When the system has a clogged or partial clogged radiator more water water slips(leaks) past the vanes. If true the vanes can not create significant pressure to try to overcome the restriction caused by a blocked/partially blocked radiator.
Wada youall think? Does this make sense, partial sense, or am I crazy?
Perhaps all?
30 Closed Cab PU
Well-known member
X2
Agree, good info. Fix right, band aids OK to get you home. Band-Aids have a tendency to fail at inopportune times. 100 miles from home, on a day tour, out in the middle of nowhere, etc. Plus it is always a worry, about wondering if the Band-Aid will hold.
ryanheacox
Well-known member
Yep, and the lowest pressure of all is going to be in the head... right where you need it most. Does anybody know why Henry thought a pull through cooling system was better?
Synchro909
Well-known member
In only two words: "It's cheaper."
The option is a "Push Through" system where the water pump is between the bottom of the radiator and the block. It is not so easy to put the pump down there for the same $.
All that said, the Model A water pump doesn't create any pressure to speak of. It can, however, move a large volume. I doubt it is capable of causing a low enough pressure in the block/head to lower the boiling temperature much at all. If the SLIGHLY lower pressure were enough to do that, the system is @#$%ed anyway.
Remember, the Model A cooling system can best be described as "pump assisted thermosyphon". With a good radiator, you can drive without the pump - I've seen it done by a club member on a 1,500 miles drive.
pinball73--I did the same thing shortly after getting my car. Rad. guy had a great reputation. Cleaned tanks, would not rod out the tubes, and repaired the several small leaks as best he could.
If the "in car" test tomorrow fails, out it comes. Will get it checked and go from there.
If the "in car" test tomorrow fails, out it comes. Will get it checked and go from there.
Jacksonlll
Well-known member
Last summer our club set up a way to flow test a radiator in the car. It takes a bigger pump than we had, have a bigger one now, but we were able to identify a plugged radiator easily. 36 GPM is a lot of water. More than my old sump pump could do. Will do more on this, this summer. Our member heading this effort, Dave has got the set up figured out.
Jacksonlll
Well-known member
I did a test last summer on my car that has a good radiator. I ran the engine at about 2300 rpm. I think that is the engine speed for about 45 MPH. I put a pressure tap in the lower hose, expecting to see a lower pressure there at the higher RPM, but got absolutely no difference, meaning that the radiator was easily flowing at a high rate and that the pump was not causing any, measurable, lower pressure in the engine. With a plugged radiator, I still think I would have seen a lower pressure down at the lower hose. Will have to find a car with a plugged core to test again.
30 Closed Cab PU
Well-known member
Rereading this string, looks like this was not answered. Plus am summarizing what may be happening.
A good starting point is to read the recommendations in the Model A Owners Manual. There should be a free download available on line if you do not have one. If you can not find it, ask here, someone probably has the link.
Depending on the car, adjustment of GAV and Spark Lever varies. Depends on the condition/wear of the car, and how the base settings are adjusted/calibrated.
At speed, with engine warm, under load (hills) GAV should not be set too lean, can make engine run hot. Usually should not be set less than 1/8 to 1/4 quarter turn open. If the spark is set retarded (lever up), and the GAV is not set correctly, motor can backfire, especially at low speeds.
Spark lever under same conditions should not be either over advanced lever down) or overly retarded (lever up). The tendency is to run with the lever fully advanced (lever down) on hills since it gives you the most power, but this is not good on the motor.
A rule of thumb is to set the Spark level to match your speed when adjusting the lever, half speed/half advance, full speed/full advance, idle-very slow speed/not full retard but a few notches down on the lever. Lever full up retarded, only when starting and once motor pops/runs set down a few notches. At idle it is ok for a very short time to run full retard, not really great for the motor, and causes motor to heat up, amongst other things.
For your issue your having, try the same route repeatedly, and try different settings each time. Write down the results.
What would be very helpful is if you had a coolant temp gauge, the type where the sensor is in the head upper coolant neck, with a gauge inside your A. Makes it easier to diagnose, and handy to keep track of Temp if a problem is about to occur. Moto meters give you a rough view , I find a temp gauge a lot more useful.
I suspect your issues are not GAV/Spark setting related. However these are easy things try and rule out in the progression of trouble shooting cooling issues. IMO these may help, but are not the real cause of the problems. Cooling issues are; marginal/bad radiator, bad head gasket, excessive buildup of rust/scale in the cooling passages in the head/block.
My opinions based on my dealing with cooling issues, opinions may vary.
30 Closed Cab PU
Well-known member
Another string currently running on settings.
https://www.fordbarn.com/forum/showthread.php?t=256005
https://www.fordbarn.com/forum/showthread.php?t=256005
TerryH
Well-known member
I had some overheating issues with my A about 13 years ago, and our Tom Endy suggested I have the radiator rodded. I took it to an older gentlemen who knew how to do it, and he found that over 20 tubes were totally or partially clogged. He was able to open all but a few of them, and my car has never overheated again. Rodding can work if it is done by someone who knows what they are doing, and can open clogged tubes that other methods cannot.