How To Solve An Engine Overheat Condition - EricTheCarGuy

you just keep on coming back I like that hi again kids welcome to another fun-filled and hopefully educational video from eric the car guy today we have a car that is overheating it's summertime here and it's quite common but also common in the winter time so what I'm gonna do is not necessarily fix the car but I'm gonna go through a process of how to find the cause of the overheat there are lots of different things on the checklist that you can check off to eliminate possible causes and hopefully eventually find yourself a diagnosis in the process let's get started let's just do one quick note though say you're driving along and your car is overheating what should you do well you should probably find a safe place to pull over and get out of the way of any kind of oncoming traffic that kind of thing but something you can do in the interim is actually turn your heat on if you turn the heater on it works like an extra radiator inside your car turn the heat on you roll down the windows do whatever you got to do but that will help bring down the temperature should it be overheating it's just a little tip just to get you by now often times the simplest solutions are always the best never over complicate things when you're trying to diagnose something just gather the evidence something that you could also check for that's just completely simple is look for any debris maybe plastic bags or anything like that that might have gotten in front of the radiator or condenser and if that's the case remove that stuff and he will allow air flow if you block the air flow through the radiator it's a good possibility it can overheat so don't overlook just looking for debris in front of the condenser radiator as long as you're under here might as well look for any signs of coolant leakage that you might not be able to see from up top this I actually think is since it's over towards the overflow might be where somebody dumped something because that's actually the transmission it's not likely that that's leaking coolant step 1 let's find out if it has coolant in it but-but-but-but make absolutely sure you do not take this off when is hot if you do this you could get severely burned because once once this cap is pressurized and once you take the pressure off the system all this stuff can come flying out and possibly burn you so do not check it here when it's hot the first place I usually check is in your overflow and this overflow is really difficult to see as far as what's in it take the cap off and look down in and it looks like this one is completely and totally full so it shouldn't be this full so we're actually going to have to take some out of here it should only be filled up to that there's a line down on the side there that's not the reason it's overheating though but I know for a fact this engine is stone-cold because it's been sitting overnight so I can just take this cap off any problem now yuck there's some goopy yucky stuff down in there it doesn't look so good but as you can see there's coolant all the way at the top if it's absent then that could be the problem if your coolant is gone then you need to find the source of the leak whether its internal external or whatever the next step in the process that I use is I'm going to pressure test the system this is a device that attaches to the top of the radiator and in doing so you're able to pump it up and put pressure on the system if there's any leaks in that system except like rolling them around if there's any leaks in that system they will begin to leak under pressure so it's a it's a good valid test to do this it may require gonna die a flaw it may require special adapters to get between the end of the tester and the radiator itself here are a couple and they have different ends depending upon what type of radiator you have so you may need to get special adapters in order to do this part of the test can now we need to fit and decide which adapter pretty sure it's this one is going to work it's actually quite simple and once you've got that clicked on there now it's a matter of pumping it up I hear something probably yes actually I've already found the problem when I pump this up you can see the fluids squirting out right there at the top of the radiator so this one was pretty easy to find but just in case yours isn't so easy to find let's go through the rest of the steps for an overheat okay as you've seen here this leak was fairly easy to find but what you're looking for when you pump up the pressure tester is you want to pump it up to the same pressure that is on the radiator cap this one says 0.9 on here and what that means is actually these things are a lot of times measured in atmospheres just as a rule of thumb 1516 psi don't exceed that don't go up to 20 I haven't seen an automotive system yet that was above like 17 psi and one atmosphere I think is around 15 psi just an FYI well as your pressure testing what you want to do is put the pressure tester on leave it set and take a look at the gauge if when you put the pressure tester on you see a precipitous drop like that most likely means there's a large leak or you haven't got it hooked up correctly so check your connections and if those are all good look around for that huge leak it could should cause coolant to go down everywhere if it's that large but if it's a small leak it may be a little harder to find but it'll be easier to find because as you see at the top of this radiator neck it will come spraying out now if the system doesn't have a massive leak you pump it up to the 1516 pound mark and it should pretty much stay there for a significant period of time actually so if you see something like this you probably don't have a leak especially if you come back in like a half-hour so so what happens if you pressure test the system and you can't find the reason for your overheat anywhere you can't find any external leaks that kind of thing well here's the next step and that is to bleed any air out of the cooling system which is covered for the most part in another video so if you haven't seen that bleeding a cooling system video you might want to go there and check in fact I might even post a link right here okay enough of that next step lead the cooling system now the reason I believe the cooling system for the next step is really for two reasons the first reason is to make sure there's no air in the system if there's air in the system it can cause the car to overheat but the second reason is because I want to verify the operation of the cooling fans if you're overheat happens while you're sitting in traffic but doesn't as you're driving down the road it's quite possible that it's an issue with an electric cooling fan not turning on like it's supposed to if it's not moving air flow the radiator then it won't cool the car but as soon as you start driving airs moving and it will cool a car so the next thing I want to do is bleed this out and verify cooling in fan operation okay well I'm actually ending up replacing the radiator on this car and as I mentioned one of the things you want to look for is debris that may be in front of the radiator well sometimes that debris can get lodged between the radiator and the condenser and while taking out the old radiator I have something to show you take a look at this do you think this blocks air flow yeah I'd say yes I would definitely say yes moralist or II do not overlook air flow issues because they could just as easily be the cause of an overheat problem as anything as a coolant leak or any other thing that you may think up keep it simple and look for debris blocking air flow I decided to replace the radiator in this car before I heated it up and bled the cooling system out knowing that I was gonna bleed the cooling system out anyway so here we are after the radiator replacement and now I'm gonna plead the coolant so at this point the temperature gauge is a little more than halfway and the cooling fan still hasn't kicked on we need to figure out why now the first rule in diagnosing any kind of electrical problem is don't rule out the obvious check the fuses and in this case also check the relays to see if those are good okay here's the 30 amp for the fan some other stuff for the headlight let's check that out look at that I don't know if you can see that too well you know it looks like a good fuse let's take it to the ohm meter and see if it works now to make quick work of this I'm gonna use my power probe somebody that actually asked me to do a video on its use that is an excellent idea and eventually I hope to but this will show you how I'm gonna use it here to check out the fan circuit first you have to hook the leads up to the battery positive and negative once you've done that it allows you to supply power and ground to a circuit but it has this handy pigtail which is a ground so a quick check for continuity in something like a fuse is if you just touch the alligator clip to the contact inside there and then touch the other side if you got a ground on the circuit fuse is good so we can rule out our fuse and plug that back in well what about this relay actually I need to get something else second thing I'm gonna need is my trusty D vom I'm gonna set it for the resistant end I'll also do a video on how to use this but what you're looking for is this little upside-down horseshoe looking thing which basically stands for resistance my meter is set up to where when you have continuity in a circuit it will make a noise and for checking a relay that's all I need now if you look at the top of this guy you can see that it's got a diagram there now what you're going to do is you're going to supply a power to these and then this other one over here clicks basically a relay is an electromagnet and it uses a low current circuit to control a high current circuit and the way you check it is you supply power to the low current circuit you listen for the click but the click doesn't always mean that you've got continuity that's what the de OMS for so I'm going to hook up my power probe across these two terminals in here which are 1 & 2 & 4 5 & 3 and they've got that little picture up at the top tell you which ones which 4 5 & 3 I'm going to put my DB om across that to see 5 continuity after the relay clicks if it clicks at all this is my ground for my relay 1 & 2 look like they're on the outer sides so and and usually on relays the hyep circuit is better metal in the low amp circuit is like the cheap metal so if you're if you're wondering which is which if you if you see like gold or copper like you see in these that's usually the high inside and low I up sides this other part so I do have continuity here so let's see if it clicks it's clicking then relay maybe ok the reason why they have relays is because if there is I'm going to turn the sound off on this thing which I can do because if there is an issue with the circuit you're controlling high amp you're not going to burn up your switches by using relays that's why relays you use relays they're used to use low amperage circuits to control high amperage circuits so this is kind of tricky as you will see is what I'm listening for here is gonna be my DV om going beep when I click this here this relay is good since I can still look still supply power and ground first I'm going to check to see what I have at the fan itself at this point because I've checked the fuse and the relay if I'm getting power and ground to the fan the fan doesn't move it's quite possible two fans bad now anybody that works on Toyotas may note that the relay that I just checked is not for the cooling fan of this car the reason I pulled that relay was because I had found a plastic cover for the relay box that had melted above this particular relay and thought it might have something to do with the circuit not working the real cooling fan relay in this car is located next to where I found the fuse something else important to note about that particular relay is that it is a normally closed relay which means it works the opposite of the one that I just showed you in other words at rest that relay is active and when you activate it it opens the circuit so when you test it it would be just the opposite when you hook up the DV om it'll beep immediately and when you activate it it'll stop beeping that's the way it's supposed to work not all relays work in a normally open system ok the connector for the fan is right here ow I'm gonna do it and just for the heck of it I'm going to see if the fan itself can work as far as power and ground here at the connector I'm not gonna worry about that so much because I can do everything I need to do with this and this actually has a circuit breaker in it so that if there's too many amps going through it that it will kick the circuit breaker and not burn anything up but you can only do this with circuits you know there are 12 volt circuits because this is a direct main line to the battery so you don't want to supply power to a circuit that's only supposed to get a lower voltage than battery voltage but cooling fan circuit is a definite so let's see if we got a ground first turn our beeper back on that what we know we have ground and if we touch this terminal here and we don't see a ground I have my doubts that we're even going to get it to work at all we learn this cooling fan is dead so I'm touching it and definitely touching the other terminal I'm getting a ground but if I don't see a ground here this cooling fan is burned up without a doubt as if this cooling fan was good right now I would see that and I'd be able to hit it with 12 volts and it should run I think it would pretty much know what's going on with this yes it was the radiator yes it was also a problem with air flow and yes the cooling fan burned up I suspect that it all came from basically the debris that was blocking the airflow through the radiator and the cooling fan was probably running all the time and heated up the relay enough to melt some of the plastic on the cover eventually I think the fan itself got burned out we'll find out after I put a new one in right now that I'm thinking about it let's talk about two other things for your overheat problems everybody talks about these this is a thermostat it is basically a mechanical valve as this spring's springs as the spring heats up and cools it expands and contracts and opens and closes this valve there are two things that can happen to a thermostat one is that it can stay stuck closed and either you know for whatever reason it is a mechanical device and over time it will wear out if it gets stuck closed then it won't allow coolant to circulate and you could have an overheat problem one of the symptoms of this is if the thermostat is stuck closed your upper radiator hose will probably be really really hot and your lower radiator hose will be unusually cool and that usually means that coolant is not circulating through the system so thermostat another one the other thing a thermostat can do is be stuck open and the temperature will never come up to temperature so in other words it will open too soon or be open all the time and and the other thing is this coolant temperature is pretty important as far as a fuel injection system goes so if it's stuck closed or stuck open it really throws off the fuel system and you may even get on some later model cars to check engine light so service that being stuck closed or open stuck closed can cause an overheat next on the list and most overlooked this is the most overlooked thing and probably the easiest thing to work with that's these guys yeah these are both jabber to your caps but the radiator cap is huge and when I say huge I mean huge the radiator cap performs three functions the first function is it keeps pressure on the system and that pressure is dictated by there's uses some markings Europeans and Japanese seem to mark them in atmospheres and this one's one point one atmosphere so this one will be roughly a 16-pound cap for every pound of pressure that this cap is able to maintain on the cooling system it raises the boiling point of the coolant two degrees so this is a 15 pound cap it raises the boiling point of the coolant 30 degrees that's significant so if this thing fails the coolant will boil 30 degrees cooler than it would normally without this cap and that's the other reason why when you take these caps off where coolant comes shooting out because suddenly it's exposed to the atmosphere no longer has as a pressurized system and it boils immediately and that's when stuff comes shooting out and that's why you don't want to take these off when the engine is hot so very important in that regard the two other functions are really very similar this has two valves in it one valve when pressure reaches that 15 pounds or whatever opens up and allows coolant to pass from the top of the radiator to the overflow tank now some systems granted some systems don't have an overflow they have what's called an expansion tank and that is a pressurized reservoir in the system and they work a bit differently but the radiator cap is still just as important there's no external tube that leads from the top of the radiator to an overflow many an expansion tank system it's it's very different you see that a lot of affords but then conversely what happens when the coolant when the car is cold and starts to cool down this valve opens up and allows the coolant to travel from the overflow back into the radiator and the cooling system topping it off so it this radiator cap not only does it hold pressure and raise the boiling point of the mixture but it takes care of the overflow on some vehicles from the system both sending it away and bringing it back lots of important functions with this radiator cap I can say that if you go to replace it replace it with a quality unit the cheaper ones of course are made of cheaper stuff and cheaper stuff doesn't always function as good as the right stuff the way a radiator cap may cause an overheat problem is is really kind of twofold what I've seen is the valves inside the ready to cap fail and say for instance it will allow coolant to exit the cooling system and go to the overflow but say that valve is bad and it won't suck it back in so over time what it'll do is it'll keep filling up the reservoir but it will never take it back if that's the case the cool will get low and the car may overheat so if you haven't overheat because of low coolant and you can't find where it's going after pressure testing and head gasket testing and everything else take a look at the see if this valve is okay I've actually seen some cars wear this this valve is missing it's gone and there were to be seen but do I have an example I knew there was a reason why I keep this junk there you go here's a very similar radiator cap and this is all that was left of it when I took it off so I took it off and these pieces were just laying down in there and you know this could be this could be caused by something else that the cars overheating for another reason it can cook these valves top of the radiator could get really hot and bad things can happen in fact I think on that Toyota we replace the radiator on the overheat actually crack the radiator I think that's what caused it but yeah radiator caps don't overlook them now back to you air saying you go through all this trouble you don't find any coolant leak you bleed the air out of the system you don't find any external leaks with a pressure tester or anything like that yet you still have an over overheating problem there is another possibility and that possibility is that there's a combustion leak into the cooling system sometimes this is a cylinder head gasket failure sometimes it's an engine mechanical failure like say the there's a crack in the cylinder head or something you really won't know and so you take the engine apart but in order to diagnose whether or not you have a combustion leak into the cooling system you can use this which is a block test kit inside this kit there are a couple of things you can find these at most auto parts stores this in my opinion is the easiest way for the do-it-yourselfer to find a combustion leak and it comes with this little vial right here and this end is what goes in where the radiator cap is you don't want to suck up any coolant so if the cool it's already low and you suspect a head gasket problem leave it low because what you're looking for is the gas you take some of this tester fluid and you put it into here like so fill it up - they have a fill line there put the cap on then you've got this cool little bulb thing with this metal thing on one side and then open end on the other the open end goes in here now you hold this over the radiator opening try to seal it off as much as possible so that you can suck up the air from inside the radiator as you do so and I'll show you a clip here that I have from another video that I shot than I ever posted if this fluid turns from blue to green or sometimes yellow that's an indication that there's combustion gases in the cooling system and in that instance your engine's gonna have to come apart in order for you to figure out what's actually going on with your overheat real sorry about that this covers the step by step and actually we did find a couple of problems on this car so it was a real good example and once again I went through I fixed the radiator but then I wanted to verify the repair and see if it was gonna overheat it's still overheated and you believe we found out why and that's because the cooling fan has has gone bad in summary first check for leaks number one cause of an overheat problem is low cooling if I know where it went next make sure there's no air in the system air may have been introduced for a lot of different things if you just had like a radiator or water pump or something replaced and now it's overheating if the cooling system wasn't blood out properly it's quite possible that there's trapped air in the system that will now allow it to cool efficiently and cause it to intermittently overheat check for air in the system next on the list air flow check to make sure that air flow through the radiator is is clear if there's like any kind of debris bags whatever that are stuck in your grill or in between the condenser and the radiator like we saw with all those leaves that's gonna diminish the cooling capacity of the radiator itself and it could overheat because of something like that in addition to that make sure your cooling fans are working the cooling fans aren't working it's not gonna have air throat air flow through the system and as a result could quite possibly overheat a quick way to check the cooling fans to see if they're working it's just too auditioning on if the air-conditioning functions if your air conditioning doesn't have a low charge it's not going to turn on but if your air conditioning has the ability to turn on when you turn on the AC both the cooling fan should come on if both cooling fans don't come on if you have two then it's quite possible you have a problem lastly you have the possibility of combustion leak into the cooling system causing an overheat problem also it will call it school coolant loss because the coolant will get burned we may see white smoke coming out of the tailpipe stuff like that so if you got any of those symptoms and your car's overheating this is this is what I do you may do something different let me know in the comments below anyway i'm eric the car guy always here to help you the viewer thank you ever so much for watching and i hope this information was helpful and will be useful to you in the future if you feel inspired by this video in any way you haven't already please hit the subscribe button at the end you can also visit me at eric carr gomm anytime i love visitors and of course my classic tagline you say have fun stay dirty

Channel: EricTheCarGuy

Views: 3,334,296

Rating: 4.827724 out of 5

Keywords: engine overheat, overheating engine, thermostat, stuck thermostat, head gasket, blown head gasket, checking for blown head gasket, leaking coolant, coolant smell, radiator, leaking radiator, running hot, engine hot, temp, hot engine, cooling system, no cooling, cooling fan, antifreeze, water, water temperature, temp gauge, temperature gauge, hot, fan relay, cooling fan relay, air in cooling system, automotive education, automotive how to, ericthecarguy, eric the car guy, etcg

Id: hUzOTnsWImI

Length: 26min 9sec (1569 seconds)

Published: Tue Jul 20 2010