With Spring on the horizon, and Summer not long behind, it will soon be time to check that your Jeep's cooling systems is working and ready for the coming hot days ahead. Suddenly, any parts that might be in question can fail or burst, or simply give out, and the next thing you know, you've over heated your Jeep and maybe damaged the engine and other components. Let's take a look at some of the parts in your cooling system, and things to check while you're under the hood. It doesn't matter if you have a new Jeep or a an old one, it's a good chance to look around and just give it all a general inspection before the hot temperatures hit. Radiator Cap -
Let's start with the simplest item first. Your radiator cap should have a good seal. There's a rubber gasket inside it that often times gets thin and worn out, and doesn't let the cap seal tight against the lip opening on the radiator. See how it looks. If it's not getting a good seal, that means the water in the system can slowly evaporate past the cap. (NOTE: only check / take off the cap when the engine is cold, NEVER when the engine is hot). Hoses -
There are two basic hoses. These traditionally run from the radiator to the engine. There is one on top, which flows the water from the engine into the radiator for cooling. The bottom hose flows the water from the radiator into the engine (normally the water pump is actually pulling, or pumping the water from the radiator with force). These hoses are connected to the radiator and to the engine by clamps. These clamps should be inspected for any issues. You're also looking around the clamp, and around where the hose meets the inlet and outlet for any discoloration from water rust or coolant / antifreeze that might be seeping out. Just about every vehicle will also have heater hoses. They have a thinner diameter, and run from the engine to the firewall. These can be made up of multiple hoses and connections, and on newer vehicles, will have specific molded shapes. Check all the connections and look for damaged or seeping hoses. Check where they meet the firewall as well. These heater hoses will connect to the heater core, which uses the hot water to heat your air when it blows inside your interior. Most of the time the heater core is inside the firewall, in the interior, under the dash. It would be difficult to really inspect that, but if you have any liquid coming from that area into your interior, a heater core could be the problem. Fan Clutch -
If you have a mechanical fan on the front of your engine, which draws the air through your radiator, you probably have a mechanical clutch as well. The clutch part allows the fan to spin at different speeds, meaning, the fan will rotate at the same speed as the engine, while at times it may turn slower, in a free wheeling(slipping) kind of rotation. There are reasons for this, including better gas mileage and /or robbing less horsepower from the engine. Of course, the main reason is so the fan can adjust to conditions to better cool the radiator when needed. There are two kinds of basic fan clutches. A NON-thermal fan clutch, which is more mechanical, and adapts with simple rpm. The other is a THERMAL: clutch which uses temperature sensing spring. Depending on the temps, the spring expands and contracts, effecting how much the clutch will slip, and cool the engine properly. Fan clutches go bad over time, like any other kind of clutch. This can cause overheating problems, and even effect your air conditioning and other systems. With the engine off, if you try to turn the fan by hand, and it's to stiff, the clutch may be binding or seizing. If the fan spends to freely, with next to no resistance, then it may be worn out and is slipping to much. Make sure it is bolted and mounted tightly also, and not cocked or bent. Note that some newer vehicles use an ELECTRONIC fan clutch, and those work based off the computer controls on the vehicle. Those will require more diagnosing procedures. Thermostat -
The thermostat is mechanical, and regulates the flow of water through the cooling system and your engine. When your engine is cold, it's closed. This allows the water to circulate only in the engine so that it will warm up, and thus, warm up your engine. Once a certain temperature is reached, the thermostat will open, allowing the water to flow from the engine into the radiator, so the engine will operate at the right temperature from then on. While the thermostat isn't visible to check, it's usually contained in some kind of housing. So you can check the housing and see if there is any seepage or discoloration around it from coolant / antifreeze. There is usually a gasket or rubber o-ring to seal the housing to the engine, and those can go bad over time. That's why you want to inspect it from time to time. In the old days, many people would take a thermostat out and not use one. But on newer vehicles, especially with computer controls, you don't want to do that. This can cause the engine not to run at it's optimum temperature for the computer to calculate the best air / fuel mixture, which is what gives you the best gas mileage. Some people run a different thermostat temperature, meaning, they go from a stock 180 degree thermostat to a 160 degree one, for a cooler temperature. Again, this can throw off the computers calibrations, so it's not really a good idea on modern vehicles. In most cases, you can tell if a thermostat is at least opening. When you start you vehicle cold, take the radiator cap off. Watch the water in the neck. After a few minutes, the thermostat will open, and you will see the water now moving and flowing in the radiator. Water Pump -
The water pump is the critical part. This pumps the water from the radiator to the engine, and ends up pushing the water all through the cooling system. Check around the pump for any seepage or leaks. On most external water pumps, at the bottom, literally underneath, is a small hole. About the diameter of a pencil. That is what's called the "weep" hole (see above image). If you see that it looks like any fluid is seeping out of that hole, that means the water is seeping past the seal inside that separates the fluid from the bearing. That water pump needs to be changed soon. If you can, you should also check for play in the output shaft in the front of the water pump. If you can reach in and grab it, try and move it around. You want to make sure there is no play. If there is, then the bearing inside may be worn. Heater Control Valve -
On a vehicle with a heater, there is a valve that redirects water from the cooling system and feeds it to the heater core (the image above is a generic valve). This allows hot water to run through the heater core, and heats up the air before it blows inside your vehicle. By using the dash controls, you're opening and closing this valve. On older vehicles this was done manually, but modern vehicles many times do this electronically. Sometimes these can get stuck, or fail to operate properly over time. So a quick inspection is about all you can do, and make sure the heat is working inside your vehicle. Check the hoses running to the valve and look for leaks or seepage. Some valves may use vacuum to operate some of their features, so you can check that hose as well for cracks or degradation, things that might cause a vacuum leak and cause it not to operate correctly.. Radiator -
The radiator cools down the water that flows from the top of it internally, down to the bottom. Hundreds of small cooling fins allows air to travel through the radiator. The main part of a radiator is usually made from aluminum or brass, while the tanks on each end can be metal or plastic. For the most part, all you can do is inspect it for any seepage on the outside. If the water level is low, you can inspect it inside the fill hole for any discoloration, floating debris, or sludge. Coolant / Overflow Bottle Tank -
The coolant overflow tanks are usually plastic. Over time, they can develop a crack or a leak, So inspect the bottle, especially underneath, for any seepage or stains that might indicate an issue. The cap on top should be tight. If the cap is too loose, or it's missing, then water in the system can evaporate out. Check the hose that runs from the radiator to the tank, to see that it's tight and has no leaks. Coolant / Antifreeze -
Coolant is a chemical additive you don't see much anymore. It has no antifreeze ingredients in it, so it's primarily used in southern / hotter areas. Most of the time it cost less than antifreeze, and that makes it popular with some car owners. Antifreeze of course is designed not to freeze in northern winter climates, and it will include coolant properties as well. A common cooling system uses water and antifreeze. A basic fill ratio is around 50 /50, but different vehicles may require more or less proportions (check your owners manual). This means half of the fluid is water, the other half is antifreeze (this includes the fluid in the engine and heater core). Water is what transfers the heat from the engine and through the cooling system. Antifreeze is designed not to evaporate, but water will over time. So even if a cooling system evaporated all the water, there would still be a liquid, the antifreeze (coolant), going through the system rather than it be totally dry (which could be catastrophic to an engine). You should never run a cooling system on straight water. The water will corrode and rust parts from the INSIDE OUT. So by the time you see a pinhole from corrosion in a steel hose line or part, it's too late. Of course, up north, straight water would freeze, and that would not be good either. Also, antifreeze usually has chemicals that lubricate the water pump shaft to help it last longer, and with straight water, you will lose that benefit. While some people do run straight antifreeze, without the water to help transfer the heat, ithe cooling system will not be as efficient as it could. So there's no advantage I can think of for doing that. Antifreeze can degrade over time, so the cooling system should be flushed and the antifreeze and water replaced. Check your owners manual for when you should do this maintenance. NOTE:
that antifreeze is poisonous. If you get it on the ground, pets can lick it up (it taste sweet to them), so always dispose of any new or used antifreeze safely. Heater Core -
This is not so much a part of the cooling system, but the engines water does run through it when you turn the heater on. It's normally located under the dash, so there won't be much to check. (except the lines as we mention above). You should at least turn your heater on a few times a year. This allows the cooling system to flush out the standing water sitting in the heater core. If you only use the heater once a year, that means the water has been sitting in the same place in the core for a year. That can get nasty. A few minutes of your time running the heat over the course of a year now and then can keep fresh fluids inside it. So why are radiators black? -
Some radiators, especially older ones, were made of brass. If the radiator wasn't painted, the brass would soon discolor, and begin to change. Like the Statue of Liberty (which is covered in copper, one of the alloys in brass, and why the statue is green), the radiator would soon have a noticeable green hue. Who wants to buy a vehicle with a discolored green radiator? Might as well cover that up with some black paint. Modern brass and aluminum radiators don't have that issue so much, so, as far as high performance and racing radiators, most of the times they aren't even painted. But car companies still make them black (and that in turn matches the black plastic tanks a lot of them have today). Can water / antifreeze get mixed with the oil?
Usually by the time you are aware of this problem, it's a serious issue. Your water will be brown and maybe have some sludge properties to it. Oil floats on water, the two fluids don't really mix together well, and this makes for a nasty fluid. If you check your oil, or can see inside the engine via the oil cap opening, and you see more brown sludge or discoloration, then somewhere in the engine, something has happened where the two have mixed. The most common reason is a bad head gasket. Those gaskets form a barrier between where the oil runs through the engine, and water passages. If the gasket fails, pressure pushes one fluid to mix with the other. Now both systems, the cooling system and engine oil system have been compromised, and will cause engine failure if not repaired soon. While a "blown" head gasket is hard to predict or prevent against, keeping your cooling system up to specs with regular maintenance can help prevent the engine from overheating. When an engine is overheated, this can cause the engine head (specially if it's aluminum) to warp, which can cause a head gasket to fail. By spending a few minutes checking out your cooling system on your Jeep or Truck, you can help catch any issues that might cause overheating, or leave you down on the side of the road. Worse case scenario, you could have a problem while trailing, miles from any help or repairs. So grab a flash light, a cold drink, and a lazy afternoon to check out your system today See ya on the trails !