The Definitive Guide to Radiators

[EVO-V]

We seem to be caught in repeating ourselves on which radiator is best for what. Worse, we're finding ourselves having to refute misinformed marketing myths, and pseudo-science time and again. So much so that discussions regarding matters pertaining to troubleshooting and decision making towards better reliability and value are sidelined.

This will be a 4 part series, that will be provided in installments as time allows and shall be updated as necessary.

I'd like to ask the mods if they would be kind enough to give me the ability to edit posts on this thread, for errata/revisions/updates. Hopefully this becomes a sticky as well and would be of help to more people.


Part 1: Aluminum vs Copper-Brass Mythbusting and General FAQ
Part 2: Repair or Replacement
Part 3: Coolant and Commonsense
Part 4: Troubleshooting

I also ask folks to please, pretty please -do not PM me for service requests, or brand recommendations. Keep questions technical and they will be answered.

[EVO-V]

Part 1: Aluminum vs Copper-Brass Mythbusting and General FAQ

1. Aluminum doesn't rust.
Yes it doesn't, but that's just because rust is iron oxide. However, it doesn't mean that Aluminum isn't prone to corrosion, on the contrary, it corrodes far faster when inhibitors in your coolants have expired. In fact in certain scenarios, ie. salt spray air (seaside), stray currents, water only systems -aluminum will corrode faster,

2. Aluminum is a better conductor of heat than copper-brass.
Better than brass -yes, but far less conductive than copper by 1.7 times. In a radiator, this is negligible given brass tube walls in copper-brass radiators are relatively very very thin for it to make a difference.

3. An aluminum radiator is better than a copper-brass radiator or vice versa.
This is a misnomer. A properly designed aluminum or copper-brass radiator will perform according to specification. An improperly designed aluminum or copper-brass radiator will perform inadequately.

4. Aluminum is lighter therefore better.
For applications where weight and cost are more of a concern -yes. In more performance-intensive heavy duty environments -no.

In this case, more fins doesn't necessarily equate to more performance if air cannot flow through the radiator core, because aluminum fins need to be thicker by up to 3 times to make up for its lower tensile strength.

So to get more effective heat transfer area without blocking airflow, aluminum radiators need to add more rows, increasing its overall size.


5. Copper-brass is heavier therefore it is stronger.
Generally yes, but it really depends on the construction and material spec. Aluminum by its nature is prone to metal fatigue that results in stress fractures.

However, some radiator manufacturers have been known to actively hide information about tube wall gauges, simply relying on the fact that people do not measure what they do not see, so as to cut on costs.

This becomes critical in high performance/high reliability applications. Tubes with materials that are 30-40% thinner are used only for radiators in light vehicles. These are guaranteed to fail prematurely in demanding environments.

Again, use the right radiator for the job.


6. Aluminum is better therefore its more expensive.
We've answered the performance aspect of this above. Aluminum is actually cheaper due to being more abundant. It is also a very light material.

Copper-brass radiators will cost more simply because as a commodity, copper and its alloys are more expensive, and is a far denser material.


7. What about those plastic tanks?
Plastic tanks were introduced as a cost reduction measure for radiators. They consist of a fiberglass reinforced polyethylene composite and a gasket which is crimped to the radiator's header.

This solution is reasonably reliable, enough for it to be implemented across the industry. However, in a lot of extreme road conditions, those plastic tanks are subject to pressure and thermal cycling that results in premature wear.

Given the rate of expansion between the o-rings, the tanks, and the header, it will be the O-rings that will wear out first.


8. Which is the better replacement, Copper-brass or Aluminum?
Given performance parameters being equal, that will depend on your purpose.

If you're on a budget, aluminum radiators provide excellent value as replacements in most cars. Taiwanese, Thai and Indonesian made aluminum radiators actually work very well. At this point, I would personally avoid, China-made radiators for quality issues.

If the use of your vehicle is demanding, either commercial, heavy hauling/lifting or long distance driving -copper-brass radiators will be more suitable. Apart from greater pressure and corrosion resistance, copper-brass radiators are repairable just in case you find yourself out of town and your radiator is damaged, a typical radiator repair shop would be equipped to repair your unit.

Motorsports will likely lean towards aluminum because of weight and general availability. However, given how much equipment and technology is packed into typical engine bays right now, conventional aluminum and even copper-brass radiators would find it difficult to increase performance without enlarging the size of the radiator.

This would often necessitate cutting and grinding underneath the hood to negotiate for some room.

Next generation copper-brass radiators with more radical tube/fin geometries are required to overcome space limitations, allowing radiators to maximize heat transfer capacity within very limited confines. This is achieved through using razor thin copper fin gauges, so the radiator can be given more effective heat transfer surface area while maintaining the overall stock dimensions.

9. What about surplus radiators?
Unless you can't find a radiator and you're willing to risk your engine overheating, this has to be a your last resort.

Surplus radiators from abroad have already been subject to wear and tear. Its condition and "quality" are not consistent and you will need a bit more work than usual to make sure it gets things working for you. This isn't a situation as if its buying a pre-loved car. There are no standards for re-validating these.

Find a vendor that will customize one for you if need be -the risk isn't worth it.


10. There are a lot of cheap replacement parts flooding the market. Which do I choose?
Your engine's cooling system is something you shouldn't skimp on. The cost of an overhaul and downtime is worth more than a proper radiator.

A manufacturer is only as good as the warranty they're willing to extend and honor.

[EVO-V]

Part 2: Do I have my radiator repaired or replaced?
This is a very common question given the proliferation of services available in most road-side radiator repair shops.

The first thing that needs to be asked is, what kind of damage are we looking at?

1. There's a crack on my radiator's plastic tank, do I repair or replace?

If the crack is on the plastic tanks it can be repaired with high temp wet curing epoxy.

If the crack is on the inlet or outlet pipe -replace it.


2. There's a leak on the tank of my copper-brass radiator, do I repair or replace?
If its a crack or a ding on brass tanks, it can be repaired with solder.

If the leak is around the inlet/outlet pipes, and as long as the joint is reasonably intact, you can still have it repaired.

But you will want to check why this happened. A leak on the pipe means that the hose may be improperly installed.


3. There is a leak in the middle of the core of my aluminum radiator. Do I have it repaired or replaced?
Sorry, even if aluminum tubes are thicker, it is impossible to weld them without destroying them.


4. There is a leak in the middle of the core of my copper-brass radiator. Do I have it repaired or replaced?
If the leak is a puncture on the broadside of the tubes, the side adjacent to the fins, it is repairable. However if the puncture is on the radius of the tube, attempting to repair this may result in the damage spreading as the material expands under the heat of a torch.


5. But the road-side radiator repair guy says he can fix this. Should I or should I not?
In larger applications, wherein radiators 1 meter x 1 meter in size are involved, it makes economic sense to replace the whole tube to salvage the radiator. This needs to be done by a vendor with access to virgin tubing.

The "expert" from the road-side repair shop, however, will likely "condemn" the tube by sealing it on both ends with solder. It will get it working...however, the integrity of radiator cores function on symmetrical equalization of pressure. Meaning all the tubes and fins exert the same amount of pressure against each other. If one fails, the rest cascade.

The problem here, is that without coolant flowing through the tube, said tube will not be able to resist the expansion of the fins adjacent to it, as they are pushed by the pressure inside

Eventually this will cause the rest of the core to fail as the other tubes/fins expand towards the point of weakness. The fins will eventually detach from the tubes and the radiator will destroy itself.


6. But isn't it cheaper to simply have my radiator repaired/overhauled than to get a new one?
First of all a properly maintained coolant system, will ensure that you would not need to "overhaul" your radiator.

Second, we need to talk about the difference between cost and value. For the purposes of discussion, cost is generally what you put out at the time of purchase while value is generally the utility you derive from said purchase.

It is natural for us to opt for the cheaper solution, often so we grow up thinking we should find the best deal without realizing that there is more than just the price tag attached to every decision.

Cost-wise repairs are cheaper -generally and are recommended in certain situation over replacements.

However, value-wise, factoring in the risk for later rework ie. more downtime, lost income, inconvenience, risk of engine damage, whatever you think you're saving is starting to look rather foolish.


7. What is this overhaul thing I see everywhere and would you recommend it?

Overhauling is generally an attempt to "restore" a radiator to a functional level of use. In most situations wherein motorists/mechanics/pseudo-scientists etc. do not take care of their coolant systems, they end up clogging radiator tubes. (Will have a more indepth discussion about this in Part 3)

Servicemen will open a radiator and stick a rod or a piece of wire to scrape off sediment and residue from the inner surface of the tubes. In so doing, abrading tube walls making it more prone to leaks.

Larger radiators for industrial use, have thicker tube walls, and are therefore more suitable for this process.

If your radiator has been brought down once for an overhaul, and no root cause analysis is done nor the appropriate remedy applied, it is more likely to be brought down again at a far shorter interval or result in catastrophic failure.

It is clogging for a good reason.


8. If I were to replace my radiator, which should I choose? Copper-brass or Aluminum?
As stated in part one, it doesn't matter as long as the radiator you choose is designed correctly.

Your cooling system, however, is worth investing in for the long term.

Special considerations only come in if your applications for your vehicles change for more extreme, heavy and/or extended use conditions.

[EVO-V]

Reserved for Part 3

[EVO-V]

Reserved for Part 4

[jhnkvn]

Keep it up pare! Although I wouldn't recommend reserving for a long time. Nawawala EDIT button natin.

[ali_diego]

very good....

[EVO-V]

Already sent a request to the mods. Don't know if they got to it or will implement it.

We're looping around the same issues in a very finite science.

Couple that with the occasional "rogue" marketing employee and you get recommendations that end up being stupid.

Maybe if enough people like this thread enough we'd get it to a sticky.

[jodski]

Voting for this to become sticky... Nicely done

[edtf]

Yup this deserves to be a sticky. I can't wait on the part on coolants

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