Lastly, let’s talk about water pump failures. This is also something you don’t see often, but it does happen from time to time, especially on vehicles with plastic impellers on their water pumps. Sometimes the blades of the impeller either rust away or get broken. For some reason (because they’re cheap), some manufacturers think it’s a good idea to use pressed-on plastic impellers on their water pumps. When these break, you get a loss of cooling system efficiency because the pump can’t move coolant through the system. It’s like a fan that’s missing a few blades; it just doesn’t move air like it should. The same is true for a water pump; broken or missing blades on the impeller have the same effect.
These are probably the hardest overheat problems to find. You can do a quick Google search on your vehicle to see if water pump problems are common with your make and model. That way, if you have an overheat you can’t find the source of, you’ll at least have something to go on. The only way to truly know if you have a water pump problem of this type is to remove the water pump and inspect it. The symptoms of an issue like this are often an overheat while driving on the highway or when the engine is under load, but it will cool down when the engine isn’t working hard. This video shows what a bad water pump looks like.
One last thing on efficiency: Don’t forget to check for stuff blocking the radiator. I’ve seen it more than once. A plastic bag or a bunch of leaves get trapped in front of the radiator, and as a result, the cooling system doesn’t work as well as it could. This is an easy fix and is often easy to spot, so don’t forget to put your eyes on the front of the radiator and check for debris blocking it. When you look through your vehicle’s grill, you’re likely looking at your AC condenser. Any blockages to the condenser will equate to blockages at the radiator because the radiator is mounted right behind it. Sometimes you need to partially remove the radiator or move it back to check between it and the AC condenser; sometimes the debris gets trapped in this area and it can’t be seen unless you move the radiator out of the way. So don’t forget to check there too. See the above video on overheats.
Engine performance issues can’t be ruled out when talking about engine overheats. Things like timing issues, both mechanical or ignition timing, can cause your engine to overheat. So don’t forget to check the mechanical timing and the ignition timing. A restricted exhaust can also cause your engine to run hot or overheat because the engine can’t expel spent exhaust and has to work harder as a result. This video can help with that diagnosis.
In addition to a restricted exhaust, a malfunctioning EGR can also cause an overheat. This is unlikely, but it has been known to happen. The job of the EGR is to cool the combustion chamber under periods of engine load. If it’s not functioning, it can contribute to running hot or an overheat. I will admit this is remote, however.
Also: low oil. If your engine is low on oil, it might overheat, so be sure to keep your oil topped off. Transmission problems also can cause an overheat, so don’t forget to check its operation too. A sticking brake caliper can cause your engine to work harder and overheat. Basically anything that causes your engine to work harder than it should can contribute to an overheat; this includes towing beyond the vehicle’s capabilities. So if you just bought a yacht, don’t tow it with your Golf GTI.
I’m not going to say you shouldn’t use stop leak products, but if you do, make sure you follow the directions to the letter. They can work, but you need to follow the directions in order for them to be effective. I talked a bit about this topic in these two videos.
As I said, overheats can be life-threatening to your engine, so don’t ignore them. With a little time, patience, perhaps some special tools, and old-fashioned observation, you can usually track down the source of the problem. Just take your time and don’t ignore the evidence.
I hope this information was useful to you. If you didn’t find what you were looking for, type in a few key words into the search at the bottom of the page. You can even type in specific check engine light codes. In addition to the code meaning you may find articles and forum posts that pertain to that code. If nothing comes up for your issue, sign up for our forum and ask your question there. We’ll be happy to help if we can. It’s free, all you need is a valid email address. Just be sure to respond to the conformation email to complete your registration. If you don’t see the conformation email, check your spam or bulk folder, it might have gotten stuck there.
Written By EricTheCarGuy
Edited By Julie Hucke
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