Changing your coolant is not an option
by Jim Kerr

Life is busy, and some vehicle maintenance items, such as changing the engine coolant often get dropped to the bottom of our "to do" lists. If it is still working, everything must be all right. Wrong. Corrosion is a silent killer of vehicles and by the time we can see cooling system corrosion, costly repairs are often needed.

A cooling system is a complex assembly of components and materials. Aluminum, cast iron, steel, stainless steel, copper, brass, rubber, plastic; an engine coolant must be compatible with all of them. In addition, the coolant must transfer heat efficiently, stop corrosion and provide lubricant for water pump seals.

This task doesn't sound too hard unless you realise that any time two dissimilar metals (such as different aluminum alloys) are placed in contact with an acidic liquid (used antifreeze), you have built a crude battery. Electricity generated by the cooling system causes accelerated corrosion of the materials. Changing the coolant when required will prevent excessive acidic build-up in the system and help prevent corrosion.

Three types of antifreeze are commonly used in light duty vehicles. Ethylene glycol has a sweet taste and even a small amount can be fatal to small animals and children so care must be used when storing or draining antifreeze. Propylene antifreeze is less toxic and has a slightly bitter taste so it is less attractive to animals, but care should still be taken to store it safely. Both ethylene glycol and propylene glycol contain silicates, phosphates and/or borates as corrosion inhibitors to keep the coolant solution alkaline. These antifreezes are typically green in colour.

A third type of antifreeze is also ethylene glycol based, but contains organic acids that protect the engine from corrosion. General Motors started using this antifreeze under the Dexcool name in 1996 and it has a five year/160,000 km life time versus the two year life time of most other antifreezes. This "long life" antifreeze is orange in colour but don't be fooled by orange or red coolants in non-GM vehicles. Check the owner's manual to see if it should be changed at five year intervals or two year change intervals.

Don't mix long life and regular antifreeze together or the life of the antifreeze will be shortened to two years. If you have to add antifreeze, mix it with water in the ratio shown on the container. Most recommend a 50/50 mixture although some cheaper antifreeze use a 60/40 mixture. Low coolant levels are a sign of a leak. If there are no visible stains or corrosion on the outside of the engine or components, the coolant could be leaking internally into the engine oil. This can damage engine bearings quickly, so have it checked out as soon as possible by a mechanic.

The most environmentally friendly way to change antifreeze is to take the vehicle to your local repair shop. Most shops now use antifreeze recycling machines. These machines flush the cooling system, clean your old coolant, and fill the vehicle with rejuvenated coolant.

During a cooling system flush, the old coolant is removed from the vehicle into the recycling machine, and then water is forced throughout the system and drained. Next, the old coolant in the machine is filtered and tested it for its strength (freezing point) and its pH balance. New antifreeze is added if necessary to increase the coolant's strength. An additive is added to balance the pH level of the coolant so it is no longer corrosive, and finally a chemical package containing extra corrosion protecting materials and water pump lubricant is added. Now the recycled coolant is pumped back into your cooling system.

While antifreeze coolants do protect the engine from freezing in cold weather, their ability to provide heat transfer and raise boiling temperature in hot weather are just as important to engine durability. Compared to water, with its 100 C boiling point, a 50/50 mixture of antifreeze and water has a boiling point near 130 C. Clean, quality antifreeze mixed in the correct proportions with water will protect the cooling system from corrosion and help protect your engine from overheating, so don't overlook that vehicle maintenance at the bottom of your "to do" list.

Maybe someone can diagnose a recurring problem or symptom with my wife's 1993 4Runner. Currently it is exhibiting some strange gurgling sound and slurping sound while she is stuck in traffic for 2-3 hours at a time ( she is a health food rep in LA and drives all over the place

So, I never actually see the problem myself.
We have replaced the thermostat recently, and she still sees no rise in temperature on the gauges. The gauges all read normal, no warning light. Just loud gurgling and slurping from near the radiator. The reservoir seems full, but maybe it needs to be flushed out?

I want to improve any system which is failing with an upgraded part when possible, any advice ? Procedures, check lists? Vendors to buy from ?

Thanks for caring...

The gurgling is from the reservoir. The coolant is getting hot and just filling up the reservoir. If you haven't replaced the radiator cap in a while it wouldn't hurt to do so. When they go bad there is no pressure on the system and it will suck in air and gurgle in the reservoir. Besides that it's normal.

Mike

Aren't there different radiator caps with varying pressures ?
Is the K&N intake a factor in the cooling system ? It is the only engine mod.
Does forcing more/faster air into the engine cause substantially more heat for the radiator ? If so what psi cap should I get ? As for anti-freeze...Do you recommend Dexcool GM brand ? We don't want to poison any of our pets !!

Is this the right TRD part for a 1993 automatic: "18.5psi V6 (5VZFE ) (All)"
http://www.brandsport.com/trd-00642-16401-003.html ??????


Also, what should my next power upgrade be for $500 or less ?
I still have the stock exhaust ? I don't want it too loud in the cabin.
I have some soundproofing material though

Thanks

Yes there are different radiator cap pressures. But in your case stick with the stock one. Besides TRD Doesn't make one for the 90-95 4runners.

The K&N air filter will not make your car run hotter. Forcing more air will create more heat, but you are not forcing more air to go in. By forcing air you must have a Supercharger or a Turbo Charger. The K&N does not force air in your truck, it only lets the motor breath easier.

As for the Coolant you must use the Toyota Coolant. It is different than the GM Dexcool stuff. The toyota coolant has electrolites that will keep corrosion from the head gaskets.

As for power wise, the only thing that is worth doing is to get some Downey headers. You will notice a difference in throttle response. You can also runs some Bosch Platinum +4 spark plugs. They also make a difference. Besides that there's not much more you can do to that motor to make it more powerful with out spending a bunch of money.

If you really want more power swap out the motor for one off of a 96-02 4runner. That's what i did and it really does feel great. I can beat a Mustang GT at the line and also at 124mph! Oh yeah i'm also TRD Supercharged.

Mike

I think it really just needs to be flushed out and refilled with fresh coolant.
It's been a while since we have done that. It's time.

Thanks for explaining those details.
It's going to our mechanic tomorrow, and to a radiator specialist also.
We are going to check all of the gauges again also.

How high is your coolant level in the reservoir usually ?

How is the Forester Holding up and good to see you here also and on www.subaruforester.com.

When my engine is hot. It's on the high mark on the reservoir.

Mike

So I had the radiator looked at, and it was the seal on the cap. It was starting to deteriorate. New fluid, new cap. All is good. Also new front brake pads. Otherwise the coolant system is in good order now.

As far as the Forester goes, that car has never had a problem ! It just hit 25,000 miles, so it will be getting some fluids and filters changed too.

CYA L8R.