Mike Plunkett
Tech Tip #4 , Radiator Buying
Used Radiator Buying
If you go to a salvage yard or a swap meet looking for used but serviceable parts, you will quickly learn that some parts are difficult to determine their quality. Buying engines on the floor is not advised without a written warranty, the same for transmissions, and electrical parts. You just can not tell by looking.
Radiators fall into this description. They are not that big a mystery to access if they are useable or not. Some simple common sense knowledge will help you out.
Most used radiators for our Fairlanes are going to be over 30 years old and should be considered "JUNK" unless proven otherwise. If you are buying an old radiator only for parts (tanks, mounting brackets, or transmission cooler) it should not be valued at over $10-$15 tops.
How do you buy a radiator that supposedly is only about 1-2 years old? The owner assures you it is like new condition. Maybe it is, let us take a look at it and see if he is right.
Many things are required to make a good radiator
Most of this section pertains to copper/brass construction radiators.
Look at its over all condition. Is it discolored from rusty coolant? This type coolant is acidic, that is why it attacked the cast iron engine parts creating the rusty coolant. The acidic coolant is also attacking all metals in the engine cooling system. Can you guess which component is the most vulnerable? The radiator is more likely to fail in a poorly maintained cooling system.
Leaks that have been present for more than a few days will wash the radiator black paint off leaving tell tail bare metal. Leaks are a sure sign of a poor radiator.
Radiator tubing material is less than .008 thick. Tubing can erode through in a short time exposed to poor coolant mixtures. Rusty coolant becomes a slurry that erodes water pump impellers, radiator tubes, and heater cores.
Solder is considered soft metal, subject to corrosive oxidation in an acidic environment. This is what causes the solder joints to leak.
Look at the header joints. This is the area where the tubes go into the flat metal panel at the tanks, is there any white oxidation on the tube joints? This is also a bad sign. Leakage at the tube to header joint will usually show as a green stain.
Inspect the fins for damage or looseness, a radiator with fins falling out is not worth having. Like wise fins that are flattened will not allow airflow through the core. This contributes to overheating.
Have tubes been cut out or pinched off? If so this indicates a failing radiator. Visual the solder joints at the tank to header and castings (hose connections) for white oxidation. This oxidation is likened to the relation of rust to steel. When the solder oxidizes it changes in molecular structure, it will no longer be soldered, nor can it maintain a proper bond, just like rust was steel at one time but can no longer be welded or have any strength.
Visually look inside of the radiator, use a flash light to get a proper indication of the interior condition. Insects and rodents love to build condominiums in old radiators.
Do the ends of the tubes appear blocked by a white crusty substance? This is called Solder Bloom, again it is oxidized solder, except at this location it causes blockage of the tubes. As solder oxidizes it increases in volume and will close off the ends of the tubes reducing flow. This can become so bad that the radiator can no longer cool your engine.
Are the ends of the tubes blocked by flakes of rust? These originate from your engine block, heads, and cast iron water pumps. The opening of the tubes is only about .025 wide, this can plug up rapidly from debris from the cooling system. The most common debris that can plug the radiator is RTV, use it sparingly on gaskets because any excess will break loose in the cooling system and be filtered out by the radiator core. This is something to consider if you experience an over heating shortly after a rebuild, when the old engine was cooling fine.
The outside of the radiator can have problems also. Are the mounting brackets in place? Some mounting brackets can be loose (common to Ford radiators) or damaged? If the mounting brackets are rusted though, they may not be reusable. Are the tanks dented or cracked? Check the threads in the oil cooler (transmission cooler), it could have stripped our damaged fittings.
Aluminum Radiators
Aluminum radiators have their own set of problems. These include poor construction methods, few repair options, non stock mountings and poor fit.
Some of the top after market aluminum radiator manufactures have some poor fabrication processes, in the name of cutting cost. If you are shopping for new or used aluminum radiators you might want to pass on the type with epoxy sealer applied at the tube to header joint. The epoxy can be recognized as a white to yellow opaque plastic material on the header where the tubes join it. The epoxy should last about 4-5 years then it will start to crack and peel up revealing the leaks under it that the manufacture built in. If buying a used one inspect the epoxy closely.
Many after market aluminum radiators do not closely resemble the original radiator, requiring special mounting methods. Some cause fan clearance problems in the Fairlanes. When buying used make sure it will fit your car, before you spend your money.
Coolant contains solids, that are in the form of inhibitors, pump lubricants, and antiboil additives. These solids will separate over time clogging the core. Aluminum cores are welded to the tanks. It is not cost effective to cut the tank off of an aluminum radiator and Heliarc it back together so it can be rodded out.
Poor coolant attacks aluminum more severely than copper/brass material. Do to the softness of aluminum, acids can eat through it very quickly. The regular service intervals for flushing and refilling the cooling system are even more important with aluminum.
A common misconception is that aluminum cools better than copper brass. This is not true, I know there will be a wad of arguments about this issue, but the fact is copper/brass still out cools other radiator materials. What the aluminum proponents meant to say was that pound for pound aluminum cools better. A like radiator measuring the same and having a like fin and tube count the copper/brass will out cool the aluminum. If all you want is a weight savings, then aluminum is the way to go.
These tools of knowledge can make you a wise buyer of used radiators in no time. Hopefully saving yourself time, money, and pain.