AMC ~ Buick ~ Cadillac ~ Chevrolet ~ Chrysler ~ Dodge ~ Ford
GMC ~ Lincoln ~ Mercury ~ Oldsmobile ~ Plymouth ~ Pontiac

Home --------Tech pages ------ Cars for sale ------ Contact ------ Ebay------ Find USA
Cooling part three
Classic American issue196


Here we are, part three of our journey through the cooling system. We have so far looked at the component parts and how they function within the system. We have also looked at the many ways in which the system can fail and brake down. We’ve killed off a member of staff and successfully resurrected him. So what’s next? Well now we know what problems to look out for, we need to know how to go about putting these problems right, or better still how to prevent them. So how are we going to approach this? Well we shall follow the basic outline of the last article and fill in the spaces with the mends, fixes and preventative measures for each given scenario.
The first area we covered in the last article was the poorly tuned engine, and how this can cause over heating problems. Unless you are fully converse with the ins and outs of the modern combustion engine then the setting up of these beasts is best left to the professionals. With older carburettor engines, vehicles from the 50’s, 60’s and 70’s, we do recommend that you regularly have the timing checked. Probably once a year maybe more if you do a lot of miles or have a high performance ignition system. This is also a good time to have the carb checked for leaks and have the float levels set correctly. Doing this will make sure that your carb is delivering the correct amount of fuel to your engine. This will not only help your vehicle run better but should also help it run more economically. We shall hopefully be covering timing and carb servicing in future articles, so as the old saying goes, watch this space. For those of you who are not very ‘hands on’ we suggest that you approach your local garage or mobile mechanic to carry out this work for you. If you are advised that parts need replacing then our advice, as always, is use the correct parts.

If towing with your vehicle is the cause of the over heating problem, then we suggest that you consider using an additional transmission oil cooler. Fig 1. These coolers are simply small radiators that fit in the transmission oil line, Fig 2, and dissipate the heat from the transmission fluid. Placement of this additional oil cooler is fairly important. The instructions that come with most coolers will tell you to fit the cooler to the vehicles main radiator, either in front of it or behind. Whilst this is usually not too much of a problem, remember what we have previously said about obstructing the airflow to the vehicles radiator. If you feel this is going to be a problem you may want to try and find a more suitable location with a good flow of air. Of course with an additional cooler fitted you will probably need to add additional transmission fluid to the system.

usausausausausaus............aFig. 1

usausausausausausa..........uFig. 2
The amount of fluid will ultimately depend upon the size of cooler you decide to use and the length of the installation pipes. As far as what size of cooler to use goes there are two things to consider. Firstly, and probably most important is the amount of cooling you wish to achieve. Secondly, you will need to consider the amount of space you have available to fit the cooler in, Fig 3. Our advice on oil cooler size is to go as large as you possibly can without causing too much of an obstruction to the regular radiator. However, some manufacturers will give you guidelines based on gross vehicle weight, GVW, Fig 4.

................................Fig. 3
Fig. 4
Even though you have measured the area available, it is always worth offering the cooler up to see if it fits as well as you expected, Fig 5. Most oil cooler kits do come complete with instructions and a fitting kit. Fig 6.


.......................................Fig. 5

...................................Fig. 6
Whilst on the subject of additional coolers we feel it worth mentioning that engine oil coolers are also available and work in very much the same way as the transmission oil coolers, Fig 7. So if you are running an engine in exceptionally high temperatures it may be well worth considering cooling the engine oil.
Of course keeping the transmission fluid and engine oil cool is almost a waste of time if the engine’s coolant level is allowed to fall. We can’t emphasise enough the importance of checking all fluid levels, on a regular basis. We would take this to include coolant, Fig 8, engine oil, transmission fluid and power steering fluid. This shouldn’t be looked at as a chore, it only takes a few minutes to check and can save hours of sitting at the side of the road and hundreds of pounds in garage bills

....................................Fig. 7

.....................................Fig. 8
As mentioned in the last article a low coolant level is probably the most common cause of over heating and engine failure. A lot of the time the coolant level is low purely because of neglecting to check and top up the fluid. However, as we have mentioned in a previous article, a low coolant level could be a sign of other problems. Remember that just because you have topped up the coolant it doesn’t mean that the problem that caused the coolant loss has gone away.
Now we did cover antifreeze and coolant in some depth during the last article. However, we would like to cover the subject of coolant colour. Contrary to popular belief the colour of coolant is not just a random factor; there is actually a method behind the madness of coolant. Inorganic Acid Technology (IAT) is the chemical composition for the traditional antifreezes that are green in colour. An IAT can be used with either ethylene glycol or propylene glycol. The normal service life for one of these IAT type antifreezes is two years, as mentioned in the last article this amounts to approximately 20,000 to 30,000 miles.
Organic Acid Technology (OAT) was the first long life coolant or extended life coolant introduced in North America in 1994. Previous to this OAT antifreeze had been widely used throughout Europe. OAT is mostly ethylene glycol based and its first dye colours were orange and red. These dye colours are still used by General Motors and Caterpillar. Other colour dyes are being added to the OAT dye list green, pink and blue to name a few. It is highly recommended that these OAT antifreezes not be mixed with other antifreeze technologies. Again as mentioned last time the service life of these OAT’s is approximately five years. IAT and OAT antifreezes are the most popular, however, other technologies are becoming more common.
Hybrid Organic Acid Technology (HOAT) is a combination of IAT and OAT with nitrates added. This HOAT particularly well suited to both light and heavy-duty applications. Two manufacturers are currently using HOAT for their vehicles. Daimler-Chrysler’s version is coloured orange and also contains 10% recycled antifreeze. However, Ford’s version is dyed yellow and doesn’t contain any recycled antifreeze. Both of these HOAT products are using the marketing designator of GO-5. Whilst compatible with each other it is not recommended to mix them with either straight IAT or OAT products. HOAT also has a service life of approximately five years.
Nitrated Organic Acid Technology (NOAT) is basically an OAT with nitrates added. This makes NOAT suitable for use with light and heavy-duty systems. Both NOAT and HOAT have very similar performance characteristics. Currently we know of no OEM manufacturer using a NOAT product. The service life is again approximately five years.
Now hold on a minute, we’re not waffling on just to get an extra page in this rather spiffing publication, but rather to show that antifreeze or coolant can no longer be accurately identified by colour alone. Gone are the days of going into your parts supplier and simply asking for “The red antifreeze please.” We currently know of two orange, two red, a green, a dark green, a yellow, a blue, a blue-green, a pink and a clear coolant or antifreeze. With this much variation, and more being added all the time, it is almost impossible for anyone to know what coolant is in a vehicle by colour alone, Fig 9. Especially if you take in to account the discolouration of the coolant due to it being in an engine for who knows how long. With this in mind if you are unsure flush the system and start again. Hopefully if you have a later date vehicle the handbook should tell which type of coolant you should be using.


.....................................Fig. 9

...................... ...........Fig. 10
Discolouration of the coolant is usually caused by small particles suspended in the coolant. It is these small particles that can build up and lead to the blockages that we mentioned in the last article. The easiest way to deal with this is to flush the cooling system. There are probably as many different ideas of how to flush a system as there are people prepared to do it. At the same time there are numerous ‘flushing’ products available which are supposed to help dislodge debris from the engine and radiators waterways. We have seen some of these flushing agents work with varying degrees of success. All we will say is if you choose to use a flushing agent then follow the instructions to the letter. The easiest way to flush the engine has to be with a hosepipe, Simply remove the engine drain plug, Fig 10, and allow the engine to drain completely, taking great care to dispose of the old coolant correctly. With the engine drained either remove the radiator cap or disconnect the top hose. The insert a hose into the radiator and turn it on, Fig 11. After a few seconds you should see water coming from the engines drain hole. This water should be carrying with it loose debris from the waterways and may appear to be a rusty colour Fig 12.

........................................Fig. 11

....................................Fig. 12

Run the hose until the water runs clear and the turn it off and allow the engine to completely drain. Replace the drain plug and top up the cooling system with the correct amount of coolant and water. This method may not clear all the debris from the system but it certainly beats leaving what debris there is to build up and cause a catastrophic system failure.
With all that we have covered in these three cooling system articles it is probably fair to say that some engines do have a tendency to overheat more than others, but this is not necessarily because these engines have flaws in their designs. The problem is that some engines are designed in such a way that they have less tolerance for overheating conditions. This means that once a situation that could cause overheating occurs, these engines have fewer margins for error, and are more likely to overheat quickly and suffer damage. However, remember that there must be a problem causing the overheating in the first place, and it is this problem that must be fixed. One classic example is the 4.1 Cadillac engine; it has an all-aluminum block with cast iron cylinder heads. When the engine is shut off, the block dissipates its heat and cools a lot more quickly than the cylinder heads, which retains the heat for longer. This heat differential places enormous stress and pressure on the head gasket to maintain the seal. A little bit too much heat and you've got a problem, which normally manifests itself as a breached head gasket. Similarly, the original 2.9 Ford engine featured a cylinder head design, which was unusually, thin. As soon as the engine began to overheat, the heads would crack, starting at the top of the head and working down the sides. The heads were redesigned in 1989 helping to solve the problem, but there are still lots of potential 2.9 overheating problems out there. Again, this was not a basic design flaw, because the heads would not crack unless the engine first began to overheat.
So to bring our journey through the cooling system to an end let us just recap a few points.
1. Overheating is usually due to one of five things:

A poorly tuned engine.
The vehicle is being used beyond its limits.(i.e. Towing, Racing etc…)
The cooling system is inadequate.
The coolant level is low.
There is an inability to transfer heat adequately.

2. If a part on your vehicle fails always replace it with the correct part or further failures may occur.
3. Always use the correct type and grade of coolant, this can be all-important, especially in newer vehicles with aluminum components.
4. If you are unsure what the problem is or how to fix it seek professional help. This is not always as expensive as you may think and can save hours of frustration trying to figure out the problem yourself.
Putting it simply you should now be well prepared for any overheating problem that might occur, even if it is a Chernobyl style melt down on the way to your next summer nationals. So until next time stay cool.


Tech Pages