First let me say i'm new here and this is my first post.....so hello everyone. I am having issues with my 98 Dakota and I am looking for some advice. I am not too good at diagnosing, but if told what needs to be done, I can usually figure out how to do it. This may get a bit long, so please forgive me.
A couple of years ago, my brake lines ruptured and I changed those. But ever since then my speedometer doesn't work, and I cant get the ABS light to go out. My emergency brake light will not go off either. When I changed the brake lines I also changed the rear shoes, but did it wrong and they rubbed. So I took it to a mechanic and he said I had the shoes flip flopped. Anyways, I took it to him and he got the brakes working properly, but the ABS light and emergency brake lights will not go off. I have a check engine light on as well, but I had that checked and was told my speedo sensor needs to be changed....so that explains that. I only tell this stuff because I dont know if it is related to my current problem. I wouldn't think so, but you never know. Now to my current problem...I have no heat coming into the cabin, my radiator fan runs constantly right after start-up and my engine never goes up to operating temperature. Last year I had a huge coolant leak in my drive way (this was months after the heat stopped working). It looked like there was oil in the coolant as well, but I thought maybe that just came off the outside of the engine as the coolant ran down. I took the car to a mechanic and said I thought maybe I blew a head gasket , or had a cracked head. He checked it over and said the head was good, and that I had a hole in my oil filter. So he pressurized the cooling system and there was no leaks...so he topped off coolant and sent me on my way. My questions are, why is my fan running whenever the engine is running, what caused my coolant leak, and why wont my engine reach operating temperature? As for the no heat, i am going to try the reverse flush, but it seems like there is more going on there. Will a successful back flush fix the other problems as well?
Sorry about the long, rambling post, but I am a horrible writer and I just wanted to say everything that is going on. Any advice would be appreciated. Thanks everyone.
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Thank you for the reply. Yeah, I aint going back to that mechanic. I have decided to learn and fix things myself. I work on 2 stroke motorcycles, so I may grow to enjoy this as well. I dont know how I find out exactly what kinda truck I have as far as engine and trans go. It is a 2 wheel drive, 2 wheel anti-lock brakes, 6 cylinder magnum automatic.
I just did a back flush today, and nothing changed. The engine also wont come up to temp, and the cooling fan runs non-stop when the key is turned. I dont know if the fan is supposed to run non-stop or not. I did some research, and got conflicting info about whether it should or not. Anyone know? I did some reading on this forum and saw something about testing to see if the coolant sensor is bad. They said to put in a paperclip connecting the terminals coming from the wiring harness. Is that right? Well, I dont know where the sensor is. The thread said it was behind the alternator, but that doesnt help me. Anyone have a picture? They also said to check the fan relay by swapping with a similar relay and see if that turns the fan off...Could someone please tell me where the relays are? Finally, I read that I should check the thermostat. Where is it, and how do I check it.
I know these questions are basic, and i'm not too lazy to do some research here, but I can look for a couple hours just to find the information in a way I can understand for just one of these questions. Any help, or links that someone could give me would be appreciated. Thanks everyone.
Sounds like a stuck cooling system thermostat and or a bad cooling system sensor both are easy to replace and cheap.
What year is your Dakota?
The V6 3.9 thermostat location is in the pic. the sensor I'm not sure of as I don't have a pic or own one but the sensor looks like this in the lower pic just look for the sensor it should be close by.
You are not forcing the A/C system to stay on if so this may be what's going on.
Open the power distribution center on the lid is the location of everything relays fuses.
if the E-fan is on, then either the engine is at 210F or higher, or the A/C is on. Those are the only 2 static conditions that will cause the fan to come on.
A dynamic event that may cause things to behave oddly, is if coolant or power steering fluid (or any other fluid for that matter) gets in some electrical connectors, it can wreak havoc by causing shorts among other things.
The leak in your driveway may have been a freeze plug that ruptured.
First off, is there still coolant in the system? I know that's a dumb question, but sometimes the simple things get overlooked.
Does the upper radiator hose get hot when the engine has been running awhile?
What about the intake manifold or valve covers? (Tip- wear gloves first to make sure things aren't boiling hot...then decide if you want to feel it bare handed.)
Let's start with these basic steps, then we can drill down.
Thanks for the guidance guys. I will check those things you mentioned, but it will be a few days (Fri) before I can get to it. I work 6:30am to 6:30pm, so it's too dark when I get home. The A/C is not on...at least not because of me. Those pictures really help. I should be able to find the thermostat, and relays fairly easily. But the sensor i'm not so sure about. I read it is behind the alternator, so I hope I will find it. Just to be clear....when I find it, I unplug it and take the end coming from the wiring harness and put a paperclip across it? If the fan stops, then the sensor is buggered? Is that right? Also, I just switch relays, and if the one I replace it with stops the fan, then that means the relay is bad? Finally, how do I test a thermostat? Or should I just replace it regardless.
Also, there is coolant in the system. That questionable mechanic filled it up, and there has been no coolant leaking anywhere, so I assume that means the system is tight. I was also talking about the fan right behind the radiator. It constantly runs, and then every couple of minutes, some pulley right behind it will wind up for a few seconds and then stop again. I havent checked the steering or transmission fluid, but I will. The fan inside the cabin blows strong....just cool air though. All the fan speeds work, but I havent checked to see what happens when I change the where the air comes out from...but I will.
Thanks again guys. If you can think of anything else I can check before Friday, let me know. I will post my results after I do my checks. I'm gonna feel good when I find the culprit and fix it....I love solving a problem.
[QUOTE=Juiceb0x1968;3105294 But the sensor i'm not so sure about. I read it is behind the alternator, so I hope I will find it. Just to be clear....when I find it, I unplug it and take the end coming from the wiring harness and put a paperclip across it? If the fan stops, then the sensor is buggered? Is that right? Also, I just switch relays, and if the one I replace it with stops the fan, then that means the relay is bad? Finally, how do I test a thermostat? Or should I just replace it regardless.
Also, there is coolant in the system. That questionable mechanic filled it up, and there has been no coolant leaking anywhere, so I assume that means the system is tight. I was also talking about the fan right behind the radiator. It constantly runs, and then every couple of minutes, some pulley right behind it will wind up for a few seconds and then stop again. I havent checked the steering or transmission fluid, but I will. The fan inside the cabin blows strong....just cool air though. All the fan speeds work, but I havent checked to see what happens when I change the where the air comes out from...but I will.[/QUOTE]
Just because you don't see it leaking doesn't mean it's not leaking, or that there's still coolant in the system.
Thermostat can't be checked.
Temp sensor is behind the alternator, yes. May or may not be a PITA to get to. I can hardly see it on my 3.9.
I was also talking about the fan right behind the radiator. It constantly runs, and then every couple of minutes, some pulley right behind it will wind up for a few seconds and then stop again.
Are you talking about the electric fan attached to the radiator, or the clutch fan that is attached to the water pump/engine? We're all assuming you mean the electric, as the mechanical is always spinning.
Also, that pulley you hear engaging is the AC pulley, if it's the top right one with a couple of silver aluminum pipes going to it. Your AC is on, which would cause the electric fan to be on, and the system to blow cold air.
OK. I will check the colant again. This may sound stupid, but what is the best way to check? Just take the radiator cap off when its cold and look? Do I let it warm up and then take cap off while its running? If you check the over flow bottle and it has coolant in it, does that mean the coolant level is fine? Also, if the A/C is on, but the A/C is not selected in the cabin, what would cause that, and how do I fix it? And just to be clear, the fan I am talking about is the electrical radiator fan that is right behind the radiator with a shroud around it. Thanks again everybody.
Turn the HVAC controls to "off." The a/c (and the fan) should not be running unless the engine is very hot.
Checking the coolant in the overflow tank is the proper method. The level varies as the engine warms up/cools down. As it cools it draws antifreeze into the cooling system to maintain the level.
Check for a radiator fan relay. It may have failed, welded shut, so that it's running all the time.
but if the fan relay welded shut (which I have seen happen, especially on a high amp draw like the fan), it wouldn't be cycling the AC compressor. Now, if the A/C system relay welded shut.....?
also, right/wrong/indifferent, my way of checking coolant level is just removing the cap when cold. It will push coolant out when hot, so as long as it's full when cold, it should be full when hot. Our trucks are unique in having mostly tankless radiators and having the cap on the hose.