Tech Q&A - Engine - Cooling System

ADDITIVES

Question:
I want to drain, and clean out my radiator - just because it looks so "messy ". After filling the radiator with distilled water do you recommend any additive to the water. I live in the coastal area of So. California and we are not exposed to any freezing weather.

Answer:
I have been using a solution that I believe is called "Water Wetter". Check with your local Auto parts store. It is usually pink in color and it causes the water to dissipate more heat. It will help prevent over heating. Antifreeze or coolant will lower the freezing level and also raises the boiling level. The car actually runs hotter with coolant, but boils at a higher temperature. Water Wetter allows the engine to run cooler because it breaks the water down so it will dissipate more of the heat. -- Les Andrews, 1998 Technical Director



CLOGGED RADIATOR TUBES

Question:
Further to your letter of Nov 11/97 and above topic, my 29 Roadster p/u, has had the radiator "boiled" out twice, (once with the gilletts lye process covered in Model A restorer-victor page), and still will occasionally overflow, not always on hot days but more often at higher speeds. My analysis is that the radiator tubes are slightly restricted or obstructed by deposits and do not let the coolant pumped to the top tank drain down quickly enough when pumped at high volume. Is the only repair to remove radiator tanks and "rod" the tubes? what is the proper "rodding" tool? Should the deposits be softened up with either lye solution or dilute muriatic acid first? Is there a suggested process for "rodding"?

Answer:
I was reviewing past messages and I do not believe I finished answering your question on radiator problem. I would first test your radiator for flow rate. It should have a flow rate of about 36 to 38 gallons per minute. You can test the flow rate by plugging up the top goose neck and the bottom outlet and then fill the radiator. It should hold about 1-1/2 gallons in the radiator. If it takes less than 1-1/2 gallons then you have clogged tubes. Remove the plug from the bottom outlet and the 1-1/2 gallons should drain in about 4 seconds or less. If it takes longer to drain it indicates you have restricted tubes. If the flow rate is good or close, the other problem of overflow at higher speeds could be caused due to a missing baffle in the top tank of the radiator. This baffle was placed inside the top tank about 1 inch down from the top of the filler neck. The baffle prevents the water from being pushed out the filler neck by the high pressure of the water pump pushing water into the top tank. Sometimes when the radiator is repaired at a radiator repair shop they forget to reinstall the baffle or the baffle could have rotted out. When you look inside the filler neck you should be able to see the baffle. This must be in place to prevent water pushing out when driving at higher speeds. Rodding the tubes is a job I have always had done by an experienced radiator repair shop. I know they boil the tank first in a hot caustic solution before removing the top tank for tube rodding.



FANS

Question:
Further to my earlier question on cooling and rodding of radiators, could you comment on the relative advantages, if any, of the 4 blade fan over the standard 2 blade fan. I have read technical discourses of the comparison the advantage of extra cooling vs. disadvantage of extra hp to drive 4 blade fan that are over my head. simple question; which is best 2 or 4?

Answer:
Sorry I overlooked your question about the fan blade. The 2-Blade fan is an advantage as it actually delivers 15% more cooling than the 4-blade fan because of the propeller style blade. It also offers less drag on the engine. The disadvantage is that most of the original 2-blade fans have internal rust and through long use have metal fatigue. They must be checked carefully for cracks. I have seen many come apart and go through the hood. I would recommend having it magna fluxed for hidden cracks and then balanced. I would not recommend the reproduction aluminum 2-blade fans I have seen. They do not seem to be balanced well or fit the water pump shaft very well.



FAN BELTS

Question:
The information you sent me about the ignition switch was helpful, so what I did was to add a switch right above the gas gage, works good and you can't see it. Problem, Do you know the correct number of the fan belt that is made by Gates, the one I now have was bought from Snyder's and is a little too small. Next problem, We would like to put seat belts in our 29 coupe but would like them to be the modern kind, shoulder & waist type, can you suggest any. Next problem, on the distributor body where the 4 prongs stick out towards the rotor, I checked the gap when the rotor turns and three of them check .035, and one checks, .016 Is this normal? If not, what do you do? Thanks for your help, we are going to Whiskey Flat days on the 14th. of this month and I would like for the car to be running at it's best.

Answer:
Glad the switch worked.

1) The original Gates belt was No. 700, but the new No. 700 is too small. Go to any Auto Parts store and get Dayco No. 22425.

2) A lot of us use the waist strap, me included. I do not know of any way to attach a shoulder strap that would give strength.

3) Common but not normal. First try to carefully bend the brass end of the rotor up to reduce the gap on the three (.035) to .025. If you can't get .025 then try to set the three to .030 maximum. Try a different rotor if necessary. Some of the reproduction parts are not the best. Now file the forth prong to get the same clearance as the other three. A setting of .025 or .030 will give you the hottest spark to the plugs and the car will run smoother. Hope you have a good trip to Whiskey Flat.



FAN BELTS

Question:
I have a 1930 Tudor and a 1931 Coupe. Bratton's offers a red fan belt; is this is correct for either of my cars? Also, are red water hoses correct for either car?

Answer:
The original fan belt was either black or reddish brown. Hoses were black with a red longitudinal stripe or all red. I wouldn't mix colors. Black belt with black hoses etc. -- Lyle Meek, 1997 Technical Director



OVERHEATING

Question:
My father and I are restoring a 1930 model A...the engine continues to over heat. We have put on a rebuilt water pump, the radiator was soldered and filled, but we think the timing may be off. Please give us some suggestions and possible solutions.

Answer:
There are many things that can cause a Model A to overheat. The main cause is usually the radiator. First you can check to see if your radiator has 3 rows of tubes. Some replacement radiators had only 2 rows. That will not provide sufficient cooling. If the radiator is old and has been in the car a long time, the fins of the radiator become loose and can not dissipate the heat. Also, if the radiator is old and has been in the car a long time, calcium deposits in the radiator will reduce the cooling efficiency of the radiator.

Now lets look at other causes of overheating. First make sure the timing is set correctly. Then make sure nothing is blocking the front of the radiator, like the license plate. If you have a new engine, it will sometimes run hot until it is broken in. There are several books and articles that have been written that will tell how to correctly set the timing. A blown head gasket can also cause overheating. Check for bubbles in the water at the filler neck. This would indicate a blown head gasket.

Question:
I am working on a 1930 model A coupe. I am having problems with it overheating. I have put on a new water pump and had the radiator redone. The water seems to be circulating through the motor just fine. I have replaced the points, plugs, condenser and timed it. I don't know what else to do. Have any suggestions?

Answer:
First lets define overheating.....is it steaming or just pump water out the top.... If it just pumping water out you may be over filling it....let the radiator find its own level...mine runs best with the water level just below the top of the core....to most this would look like the radiator needs water.

If you are steaming and you have done all the above...check your fuel mixture..you maybe running too rich. If that is ok...check your compression, you may have a head gasket leak... Keep in touch and let me know how the above checks out. -- Lyle Meek, 1997 Technical Director



PRESSURIZED SYSTEM?

Question:
Is it normal for the radiator in a 1928 Model AA truck to lose water from boiling as it seems the system is not pressurized?

Answer:
It is not normal for a AA Truck or auto to have the radiator boil over. 95% of the time the problem is with the radiator. The Model A cars had 3 rows of tubes in the radiator and the AA Trucks had 4 rows of tubes. If the radiator in your truck is old and been in the truck for 30 or 40 years or longer, it is probably time for a new radiator. The old radiators will no longer dissipate the heat because of poor connection of the tubes to the fins. If it is an old radiator, don't waste your money taking it to radiator shop to have it boiled out. That will not correct the problem. The only solution is to have your radiator re-cored or... buy a new radiator. The non-pressurized Model A cooling system works fine without a pressurized radiator. Be sure to get a 4-row tube radiator or core for the AA Truck. -- Les Andrews, 1998 Technical Director



RADIATORS

Question:
I have had problems with the engine is over-heating from time to time. I just flushed the radiator yesterday and it has appeared to help. However, I noticed the radiator has three rows of 30 passages. I believe that an original radiator had 94 passages in four rows. I was only able to get 2 1/2 gallons of water into it instead to the 3 1/2 gallons you say I should have. Would it be safe to say that the radiator could be too small???

Answer:
Some of the earlier replacement radiators were made with insufficient capacity. Sears, for example, made a radiator for the Model A in the 60's and 70's that was too small in capacity. The radiator should hold 1-1/2 gallons and the entire cooling system should be 3 gallons. If your radiator is old, the fins get loose on the tubes and mineral deposits inside all add up to inadequate heat transfer. If the radiator is small to begin with, it becomes difficult to get adequate cooling. Snyder's Antique Auto Parts has an excellent replacement radiator at a reasonable price. It has excellent cooling. I speak from experience. I put one in my delivery and have been real happy with it. I have found that 99% of all Model A overheating problems can be fixed real easy . . . . . replace the radiator! -- Les Andrews, 1998 Technical Director



WELL WATER

Question:
In the Jan. '98 issue of The Restorer, Tech Q & A section you advise "Avoid well water at all costs", why? I'm on a well and presently using well water in my Model A pickup. My water goes through an iron filter and a water softening unit, will this be OK or should I go to distilled water? I just had my radiator gone thru and it's in perfect condition and I want to keep it that way.

Answer:
The reason for the statement "avoid well water" is because most all well water contains heavy minerals that would leave mineral and calcium deposits in your radiator and engine. With the filters on your well, you are probably cleaner than city water as far as mineral deposits. I am also on well water so I know the problems with mineral deposits. Distilled water is still the best friend for your radiator. It is mineral free and should leave no deposits. Mineral deposits in the radiator tubes will cut down or prevent the transfer of heat from the water.



WATER LEAK

Question:
After putting the winter antifreeze (Sierra) in my Model "A" I get a small amount of white exhaust smoke, with a definite antifreeze smell, within about a minute after start-up. After the few puffs dissipate, there is no further smoking and no more smell. There is no antifreeze contamination in the crankcase and no combustion product contamination of the coolant system, but I have to think that there is some seepage somewhere. When running water and pump lube in the summer, I get no white exhaust or unusual smell. The engine is a recent rebuild (a few thousand miles now) and runs very strong with no overheating, even good compression in all four, and about 17 MPG touring.

Answer:
Before closing it up for winter storage I would check head nut torque to make sure they are all to spec. A new head gasket will sometimes have to be retorqued three of four times before it settles in (after the engine has warmed up each time). Take the car to a garage or radiator shop and have them run a test for hydrocarbons in your radiator water. Its a simple test most shops can make. That will tell you if there is a crack in the water jacket within the combustion chamber. More than likely it is a small amount of seepage from the head gasket. I recommend using "High Tack" gasket sealer by Permatex when replacing the head gasket. You spray a light coat on both sides of the head gasket. I have never had a head gasket leak or seep since I started using it about 10 years ago. -- Les Andrews, 1998 Technical Director


Last Updated: 04/01/2012
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