Automobile cooling systems are complex systems that are getting tougher and tougher to diagnose, service and repair. This article by Mike DuBois will offer some information about choosing the right tools and equipment and the kinds of repairs they will allow you to complete.
Cars, Oh! those wondrous, mysterious, infuriating, perplexing, things that give us all our source of income, heartaches, joy, disappointments and the occasional surprise.
This month’s column is about one of the parts of a car that isn’t what it seems or even what it is named — the cooling system. So I know most of you are already way ahead of me here! And if any of my marketing brethren are reading this, I can hear those wheels turning. Imagine a TV commercial for the newest testosterone-powered pickup truck. The announcer is going on and on about features, horsepower, cabin room etc., etc. The next thing he says though seems just a little odd…
“The XR13 Sport Pickup truck features a towing package with heavy-duty Removal of Heat System.”
HUH?!? Doesn’t exactly roll off the old tongue, now does it? Well, unfortunately boys and girls, that is officially what the automotive cooling system (actually any cooling system) does. It removes heat. Cooling, air conditioning, these are conditions with a reduction of heat. For those of you with long memories and the rest of you youngsters who haven’t been out of school too long, you will remember your physics teacher talking about energy, the motion of atoms, calories, convection and conduction…zzz…Oh sorry! I dozed off there for a minute! (That happened the first time I was hearing it and explains why I am still gainfully employed instead of living on an island sipping foofy drinks with umbrellas in them.)
Automobile cooling systems are complex systems that are getting tougher and tougher to diagnose, service and repair. This article will offer some information about choosing tools and equipment and the kinds of repairs they will allow you to complete.
There are three main types of activities you will be called upon to perform on your customers’ vehicles: Service, Diagnosis and Repair. Let’s take a look at these activities one at a time.
Cooling System Service
Cooling system service is generally made up of the activities that are performed on a functional car or truck as part of preventive maintenance or based on the OEM’s recommendations for service at specific time or mileage intervals. This service should include at the very least, a visual inspection of the cooling system, an analysis of the coolant, a pressure and performance test, and replacement of the vehicle’s coolant.
The visual inspection can take a couple of different paths depending on whether the customer mentioned any unusual conditions. These might include loss of coolant, smelling a burning smell or coolant, overheating etc. If none of these complaints are present, a close inspection of the system should suffice.
Visibility of components on vehicles is becoming more and more difficult. One great new tool that is a time saver is a video borescope. While there have been medical-type borescopes available to technicians for years, the cost was prohibitive for many. There are new products on the market now that offer video capture, still photography, the ability to download to your computer, UV filters, miniature 6 mm diameter heads and fully articulating wands, and these are now becoming more and more affordable for the automotive technician. These tools allow you to access areas of the vehicle that would otherwise require disassembly in order to see.
Once you have examined the vehicle for leaks, damaged or weak hoses, frayed fan belts, damage to the radiator, condenser, checked the fan clutch for leakage and proper performance, it is time to check the patient’s blood. OK, that might be a little dramatic, but I got your attention didn’t I? What I am talking about is the coolant. Once upon a time, we all just pulled the plug, drained out and called it a day. Well not so fast there, Sparky! Many of today’s vehicles are equipped with coolant that has extremely long life. Some are rated for 50,000 miles of service. So, now what? Your goal is to determine if the coolant is still capable of providing protection against boiling and freezing, as well as cooling the vehicle’s motor. You need to verify that the cooling system has the correct ratio of coolant to water. You also need to verify the specific gravity of the coolant (to assure correct protection against freezing and boilover), and you will need to verify that there are no contaminants in the coolant that can cause premature failure of the cooling system.
There are a couple of quick and easy ways to check coolant. One of the best and easiest ways to check the quality of coolant is with pH test strips. These litmus paper strips are designed to react to the pH or specific gravity of the coolant. The technician simply dips the strip in the coolant, and the strip will react with a color that coincides with a chart to tell you what temperature the coolant will protect you to.
Another great tool for checking coolant pH is a hydrometer. This tool uses optics to check the coolant. You place a drop of coolant on a test surface, close the cover plate and look through a viewing sight. The scale on the view screen will give you the pH of the coolant and you check that against the scale provided with the tool. Both of these methods give consistent and accurate results and let you verify the need to change coolant.
The next step during maintenance is a pressure test. This will actually be two separate tests. One test you will perform on the entire cooling system minus the cooling system cap (this cap may be on the radiator or on the cooling system reservoir). The second test and, equally if not more important, is the cooling system cap test. This test is critical because the cap is the device that controls boiling point and system seal. There are several different pressure system tester styles available. They all have some things in common. The tester will have an adapter or set of adapters to allow you to connect it to both the vehicle’s system as well as the coolant cap. The tester will have a gauge that will at the minimum read pressure and some will also test vacuum. The cooling system can be checked with pressure or vacuum. The goal is to verify system integrity (no leaks). The more advanced testers will have the ability to test not only vacuum and pressure, but also temperature. This is a must-have for diagnosing overheating conditions. (More on this later.)
Well, you’ve visually checked the system, you’ve checked the pH by one of the methods above, you performed a pressure test, and you’ve decided the coolant needs to be exchanged. There are several ways to do this. I will address a couple of the most common ways. The tried-and-true method, which has been used since Henry Ford first banged his head on an oil pan, is gravity. Open the petcock or drain plug on the system and let’er rip…or drip as the case may be!
…Ummm, Houston we have a problem! Yep, you guessed it! Many new vehicles don’t have drain plugs on the system. So now what? Well that depends on the vehicle and your shop equipment. Your choices are to loosen a hose (cheap, messy, incomplete drain); vacuum drain and fill (less cheap, effective, quicker); or fluid exchange using a fluid service machine (most expensive, very effective, time- and money-saver over time).
If you go for option one — using gravity as your friend — you may still consider some tools that can make your day go better. One is a large funnel. These plastic trays are like great big mouths that sit on top of your coolant drain. These are big enough to catch all the drips so you don’t make a complete mess out of the shop, the bay and/or yourself. These inexpensive funnels were originally designed to catch dripping transmission fluid, but will do an equally good job here.
Another indispensable item in this scenario is a good set of radiator hook tools. These tools look like a screwdriver that got dropped in the garbage disposal. With large knurled handles and bent and angled tips that taper down to a point, these tools can be used to loosen radiator and heater hoses that have “baked” on to water outlets. These tools will break the seal without cutting or tearing the hoses. If you are going the low-tech route, you should invest in a spill-free radiator fill funnel. This tool allows you to fill the cooling system back up without introducing lots of extra air (air bad!). This inexpensive tool is a must-have for many of today’s late-model cars and trucks with configurations where the nose (radiator) is lower than parts of the cooling system. The tool helps remove air locks and bubbles. These air pockets can cause sensor failures, set false codes, cause overheating and other nasty surprises.
Option two is a vacuum drain and fill system. These tools, which are operated by shop air, will help you drain and fill the system without the mess and worry associated with gravity drain and fill. The tools have dual modes that are controlled via a valve. You set the valve in one position to drain the system, and then you can introduce coolant into the system under vacuum (no air!). These tools, while a little more expensive than the low-tech spill-free funnels, are well worth the extra expense and will pay for themselves in eliminating comebacks and fighting with those tough cars that you can never get to burp!
The final option for fluid change is the use of a coolant machine. These machines operate in a similar way to A/C recycling machines. The machine has a series of valves that control the flow of fluid. The operator installs a “tee” in the vehicle’s system, usually in a heater hose. The fluid is removed and replaced via this connection. In some cases, the tee is left in place, while in other systems the technician installs a tee inline temporarily and then removes it after the service. Using vacuum, the machine drains the system, in some cases performs a leak check and then will replace the fluid with fresh coolant. The machines range from fully manual to fully automatic. While the coolant exchange machine is the most costly, it makes good sense for high-volume shops. These machines also facilitate compliance with disposal requirements of old fluids. Finally, the machines provide labor savings and a complete exchange of the old fluid, ensuring a properly operating cooling system.
Cooling System Diagnosis
When the customer comes in for cooling system issues, the complaint is usually: “My car is overheating!” Many times the problem is immediately obvious. A missing belt, a broken hose, a leaking radiator are all pretty simple to diagnose and repair. What about that car that is showing no obvious signs of parts failure, but is definitely running too warm? There are, as you know, many reasons that can cause this type of problem. I want to offer you a couple of ideas for tools that you might not have considered adding to your arsenal for diagnosing cooling system problems.
The first is a good infrared temperature gun. This tool can be invaluable for diagnosing restrictions in the cooling system, checking the thermostat opening temperature and lots of other tests.
As mentioned above, there are good pressure testing tools that incorporate temperature as one of the tests that they perform. By testing a system under pressure, you can more accurately diagnose the problem. You can verify how the system acts, and know exactly what the temperature and the pressure are at the same time. It is critical to be able to determine what is going on with the cooling system.
One tool that I think doesn’t get used enough in diagnosing cooling systems is ultraviolet dye. By introducing dye into the cooling system and running it to temperature, you can visually confirm a suspected leak before performing expensive labor operations. When used in conjunction with a UV borescope, as mentioned above, you have a powerful diagnostic combination.
Cooling System Repair
There are many, many cooling system repair tools that I think are critical and necessary, but time and space prohibit me from listing all of them. I would like to mention just a few that I think make good sense for most techs to have in their box.
A complete set of hose pinch-off tools. These tools will save the day, time and time again. By blocking off the inlet and outlet hoses from the radiator, you can remove it with minimal fluid loss. As I mentioned earlier, a set of hose pick tools is a must-have addition. You should have multiple sizes and lengths from the tiny to the giant. These will make a bad job easier and may save you losing a day waiting for a replacement hose. That is a tool that is well worth the cost.
I especially like flexible hose clamp driver tools. These tools are for the screw-style clamp used on many European vehicles, as well as fitting aftermarket clamps that are used as replacements. The shaft is flexible enough to allow access to tight areas and you can still get enough torque to remove and install the clamps. Speaking of hose clamp tools, another must-have tool is a high quality hose clamp plier. These cable-operated tools were originally viewed by many as a luxury tool or a toy. Now they are virtually irreplaceable. Many vehicles have clamps in such obstructed areas that removing the clamp without this tool is difficult if not impossible.
Post time: Oct-25-2022