Overheating
 

I have a 31 ford, all stock that tend to overheat (steaming out the overflow and cap). Im pretty sure there is no thermostat on it so, to my way of thinking, as long as the water pump is circulating the fluid it SHOULD cool (providing the rad isn't restricted). Question is, how do I determine the actual cause?. If the rad is bad, how do I know for sure. they are pretty pricey so I need to know for certain before I go the replacement route. thoughts??.

Re: Overheating
 

While the car is running, remove the rad cap and look for foaming, lotsa bubbles. If so, bad head gasket, warped head, cracked head, etc., which allows combustion gases into the water, which causes bubbles and overheating. Had the same thing on our roadster a couple years ago and had the head planed. It was .012" out of flat. Problem solved. Easy diagnosis. If engine is tight, then bad rad. Check engine first.

Re: Overheating
 

I worked in radiator shop years ago. Try this, remove lower rad. hose and rad. cap, Place hand over lower rad. outlet, fill rad. to top with water, remove hand from lower outlet, the water coming out should be a round like the diameter of the lower outlet, if it isn't round and doesn't come out round for a few inches, the rad, is stopped up with rust or with stop leak. If it's stopped up, drain all water from rad. and block, refill with common vinegar and leave it for at least 24 hrs. Now drain and save the vinegar, to remove the trash in top of rad., you need to reverse flush at the lower hose, I have a special tool that uses a garden hose and an air compressor hose with 50 psi that is inserted into the lower hose, the water and a blast of air will blow out all the trash in top of rad.

Re: Overheating
 

Are you sure that it is actually overheating?
Use a meat thermometer placed directly in the coolant to measure the temperature. Knowing the temperature for sure will help with any diagnosis.
You should not have steam coming out of the cap. Any water or steam should only come out of the overflow tube. Probably a bad radiator cap gasket causing that.
Are you adding coolant on a regular basis? If so perhaps you have the radiator filled too full and it is pushing the excess out. Don't ad any as long as the tubes are covered you are good to go.
Timing set correctly? Retarded spark will contribute to overheating.

Re: Overheating
 

When finished with this white vinegar method, do a final treatment of baking soda/water to neutralize the acidic effect of the vinegar treatment.

Re: Overheating
 

I've saved a few discarded radiators by back flushing them,I have access to an industrial hot water pressure washer with chemical degreaser.Water pump grease with dirt and rust plugs them up over time. Pulling the head and cleaning the water jacket with a speedometer cable in a drill motor is effective for cleaning the water jacket.

Re: Overheating
 

Many of the old radiators have tubes that are seriously clogged. If other methods of cleaning do not work, then it is best to have it rodded by someone who knows what they are doing. When I had mine done many years ago, it had about 25 tubes almost totally clogged, and that was after previous efforts to clean it. After that, no more over hearing issues.

Re: Overheating
 

Retarded timing and improper use of the spark is two causes of over heating . Points gap also effects timing . Too little points gap retards timing .

Re: Overheating
 

Thanks for all of the reply. It shouldn't be a timing issue as far as setting the rotor goes but now i am wondering about the spark lever. I had an issue with water being pumped right out the overflow and found that the baffle that directs the flow away from the overflow had come unattached. I reattached it and things seemed OK. I had driven the car a little with no noticeable issue but then, the last time I drove it, only 2 miles) is when it decided to go all tea kettle on me. I'm now wondering if I inadvertently left the spark retarded on the lever???. I will be moving the car into the shop in the next day or two and will check all of the things suggested. Thanks for all the input. Much appreciated.

Re: Overheating
 

I have ran full advance at speed for sixty years with no problem . Lugging the engine is not good for the bearings . I prefer increasing speed when approaching hills rather than having to down shift . I feel that driving 50 MPH where the road permits is WAY better for the engine than creeping along and having to downshift to climb the hills .

Re: Overheating
 

You may know some of the following, but am trying to be thorough.


When all is OK, may want to add a Gano upper radiator hose coolant filter to prevent future plug up of the radiator.


A lot of times when radiators get old, the contact between the fins and tubes is poor. Nothing you can do except replace. If the radiator core has been repainted, can add to the problem if the paint is too thick. Probably not your issue, but there are/were undersized radiators with 2 row tube cores. Typically the two row cores will run OK at speeds of 25-30 mph ok on a warm/day, but when driven above those speeds or when idling gradually overheat.


If your radiator is rusty inside, more than likely the block also has rust. You can use vinegar, rust 911, thermocure, or whatever. Just put it in the system and run the car for up to weeks on and off. Multiple treatments may be necessary. If using something acidic, best to run a upper hose filter to keep crud out of the radiator. The non acidic treatments absorb/dissolve the rust into the liquid - OK to run without the filter, but to be safe better to run with a filter. If acidic treatments, a final treatment of baking soda water. When done remove the filter back/flush and then flush.


With severely rusted blocks you may have to do as in post 6, remove the head, water inlet, water outlet, water pump, and use a Drill/speedometer cable flayed out on the end to break up the rust. Model As are notorious for the cylinder 4 water jacket rusting up due to poorer coolant circulation.


When things are OK - use distilled water/Napa Macs 1300 radiator treatment, or use green antifreeze.


There are different home flow tests on the radiator, but usually only indicate when a radiator is really stopped up. If yours fails, would definitely indicate a problem, but if pass you could still have a problem. If you do a search here and/or Utube you will find info on the flow tests.

Re: Overheating
 

Are you running a thermostat?
I find that helps.
Plus all the other suggestions given.

Re: Overheating
 

If you are running with the spark lever up, or severely retarded, it will sure not run well, or have any power. To me, it would be very noticeable.....

Re: Overheating
 

Rust could be an issue, The guy I bough the car from used straight water and owned it for 10 years or so and never really ran the car. I use antifreeze. There is no thermostat.

Re: Overheating
 

If you decide to use vinegar/something acidic, be aware that if it gets on painted surfaces it can ruin, or at least dull the paint.

Re: Overheating
 

If its an old radiator, then the tubes are probably plugged solid so nothing can get into the to clean them out. If not, and it overheated during a very short trip, it may be combustion gases getting into the water jacket. Retorque your head bolts. Good luck.

Re: Overheating
 

Can someone explain how a themostat might help it run cooler? If anything I would have thought it would restrict flow and reduce cooling.

Re: Overheating
 

Hello ,the thermostat will help to get water to the back of the block allowing better saturation of coolant.On some engines notably straight eights,water does not circulate fully in block,without thermostat ,creating hotspots .Thermostat should allow a better saturation of coolant through out the block slightly slowing down circulation.

Re: Overheating
 

Hmm, not convinced, an extension of the "slower-circulation-permitting-better cooling" theory would be constricted hoses, and blocked rad tubes would improve cooling. Sounds dubious to me.

Re: Overheating
 

..sorry, duplicate post!