I was on my way to school this morning, just cruising along and all of a sudden the coolant light starts flashing on my display. I had only driven about two miles at this point and I pull over, pop the bonnet and check my fluid level. It's right where it is supposed to be so I restart it and the temp gauge shoots right back up to the red and I pull over again. I repeated this process until I was able to get home (one and half hours later for 3-4 miles). So here are the rest of the symptoms: No codes, my EPC light for some reason is now staying on after the car starts, cold air coming from the heater, and all hoses connected, and fluid levels fine. I just changed the valve cover gasket this weekend and had not replaced 2 of the hose clips on the crankcase ventilator, but put them on this morning during all of this. I've searced and found that many people have had this either be a thermostat issue or water pump issue, so my questions are: 1. What do you think my symptoms point to? 2. To anyone who has either fixed or replace, how much did it cost? Thanks in advance for your help!

ps. I am currently at 46k and my radiator was replaced sometime before I bought it (around 30-36k).

 

Could just be the thermostat that is stuck closed....im actually dealing w/ just the opposite right now...I think my coolant temp sensor is bad and it's causing my thermostat to stay open therfore making the gauge read cold 75% of the time. And if it was stuck closed it would do what your car is. Just a thought.

 

So does the coolant sensor dictate the mechanics of the thermostat? Meaning that the first step in the chain of investigation would be the sensor, then the thermostat? And would the sensor throw codes? I pulled a code for the EPC light and it came up as a p0688, which is just an electronic relay code. Not sure why the EPC issue is happening but I'm pretty sure it's unrelated to the cooling system. I just checked it out further and there appears to be a slight spraying of coolant in my engine bay, and the source was from the bottom of the resevoir tank, not near the sensor but where there is the indentation on the cap side. So your problem is just giving you an incorrect reading right? Or is it causing your engine to run way cool?

 

No it is causing the engine to run really cool. Im not getting any heat out of the motor. Therefore my gas mileage isn't so great. In your case either the tank has a crack in it or the hose clamp isn't tight? The coolant temp sensor dictates what your coolant temp is. Obviously. This then regulates how much coolant is being injected into the engine to cool it or in your case is not injecting enough. If that makes sense? But if you got coolant spraying in the engine bay I would mos. def. find the source of that first then go into the mechanics of it.

 

If cold air is coming out of the heater then it means your heat exchanger is blocked or not functioning in some way. If you don't have a coolant leak then there must be something blocking it somewhere. Did the engine "feel" hotter than normal when you opened the hood? Ifso, then it's probably overheating but I'm no expert. Some things aren't adding up. I'd take it to the mechanic if I were you.

 

It felt as hot as usual, there wasn't any smoke or anything. The heat works on the vents until it starts to pass the 1/2 way mark on the temp gauge. A mechanic I spoke to on the phone thinks it might just be a bad thermostat, but who knows at this point. This may sound dumb but what does the heat exchanger do? As in what other parts does it function with? Anyone know of a price they've heard of for either a water pump or thermostat replacement?

 

Yeah... I think it is a bad thermostat and/or ECTS.... If everything is fine and then it all screws up once you hit the middle of the gauge then it sounds like a sensor or valve isn't working somewhere. Replace both if you can and go from there but don't take it to a tech JUST YET!!!! Avoid the huge repair bills. I think you can fix this one yourself.

Good luck

 

Thanks for your help. Anyone got a link to a DIY thermostat replacement?

 

For the engine coolant temp sensor

http://www.a4mods.com/index.php?page...ECTsensor.html

 

I've been reading around on the other forums and some of the senior members have said that the lack of heat from the vents is an indicator of the coolant not being circulated, hence a broken pump. Either way, I am going to get a timing belt/water pump/thermostat kit and see what I can do. I've read that once the thermostat is removed, you can feel the impeller of the water pump and if it is free spinning, it is broken. So the plan of attack is start at the thermostat and try to feel out the water pump. It sucks because I don't really want to do a timing belt job at 46k, but if I have to get in there, I figure I might as well do it. To anyone who has taken on the timing belt job themselves, feel free to post any tips or areas of difficulty. I have found a few write ups and they appear to be pretty comprehensive, but it seems that every car has its own set of issues when it comes to repairs.