OK,

I by no means am a mechanic but I can pretty much figure things out on my own through forums, Haynes manuals and friends. For about a year, I've been having a tad bit of a problem with the cooling system on my 1997 Civic EX. It is noteworthy that the radiator was replaced two years ago after the old one bit the dust.

From time to time, usually on idle in traffic (especially with the A/C on) the temperature gauge rises. I've developed some pretty fancy tactics to try and keep it down so old faithful doesn't leaving me hanging on I-35 in Dallas. I find that accelerating generally reduces the temperature (but when in traffic this isn't usually allowed). I've tried the whole turn the heat all the way up as well to take heat off the engine - this works for a few minutes and then I'm in trouble.

So, I had both upper and lower hoses replaced as I noticed the radiator could not hold coolant and my mechanic said they needed to be replaced. Convinced this was the problem, I went along my merry way with two new hoses under the hood and a bill for about $100. I now realize I could have done it on my own. Weeks later, I noticed again that El Civico was doing the same thing. I came home, opened up the hood and lo and behold I found the hose running to the thermostat was leaking. After a trip to AutoZone, I came home with a new hose and thermostat (figured I should go ahead and replace it just in case). So I replace them and thought I was in the clear. Yes, I did make sure that the thermostat was in properly.

Fast forward to a few months ago. I heard a sizzling sound coming from the front passenger side of the car under the hood (where the radiator is located). I opened it up to find the reservoir steaming hot. I went back at lunch and noticed that not only was the reservoir bone dry but so was the radiator. I filled them with water, looked for leaks and found nothing. So, I was gearing up for a 3 1/2 hour drive last week and took her in for an oil change. The attendant showed me deposits that were in my radiator and told me that I needed to have the radiator flushed (he would do it for $80). I told him that I noticed the corrosion in my reservoir and figured my head gasket was going out. He told me that wasn't the case, that it was just clogged and needed to be flushed.

Today I did the easy but tedious task of flushing my radiator convinced (since the guy at Valvoline said so) that this was going to solve my year long battle with the engine temperature. On my final trip to the car after flushing, rinsing and now adding in new antifreeze I did not immediately cap off the radiator because I wanted to top it off once the antifreeze started cycling in to the car. I'm still not sure of whether or not the coolant dropped but I did have to add a decent amount in after a few minutes. So, after about fifteen minutes of idling at normal temp with the A/C on full blast and a fresh dose of antifreeze, I noticed that the antifreeze started boiling over and that the radiator fan had not kicked on yet.

So, I have a few questions...

1) Tell me it's not a head gasket problem. Since I've been having this problem for at least a year, I have a hard time believing that it is since the car hasn't blown up yet. If so, how much should a mechanic fix the problem for? It's old and has 225k+ on it so it's not worth having fixed if it's costly. Head Gasket does sound vicious though.

2) Could it be the fact that the radiator fan did not kick on that the antifreeze was boiling? If so, what are common causes of a fan not working. I've heard something about a sensor, a thermometer, etc... give me some ideas and how can I tell which one is the problem?

3) If the radiator fan didn't kick on, shouldn't the coolant still cycle through the car vs. boiling over the opening on top?

I'm sure I'll have more questions but hopefully I've set the table enough for someone to start helping me eat at this.

 

Also,

If the coolant was cycling through the car once it went to normal operating temperature, shouldn't the engine temperature gauge have increased since the coolant was boiling?

It might be noteworthy that the outside temperature was in the 50's and 60's today.

 

well u could bleed the cooling system , chek for the fan relay and fuse , i used that have that problem with my old engine and it turns out it was a bad radiator so i replaces it with an aluminm radiator and my overheating problems were gone

 

what it sounds like is that ur fan is not engaging at all. I would start there check all the circurt breakers on ur car and see if any are loose or if there blown. If nothing is wrong there then u might have a wiring problem with the fan. Seeing that u have replaced ur rad hose and theromstat and raditor there really is no other solution to fix it. Check there and u might find the problem.

 

Is white smoke coming out of the exhaust pipe? The boiling of the coolant you describe actually might be exhaust gas seeping past a blown head gasket.

 

There is exhaust coming out that is visible in cooler weather but invisible during warmer weather. As far as white smoke, I don't think there's any of that.

I'm pretty sure it's boiling antifreeze as there's steam shooting out of the reservoir and it makes a bubbling sound as well.

 

Are you saying that the temperature gauge was not indicating an overheated engine when the coolant was bubbling/boiling? If so, this supports the idea that the bubbles are exhaust gas. You may want to test whether any of your cylinders has low compression, likely indicating a blown head gasket.

 

The engine temp gauge on the dash did not increase.

The antifreeze IS boiling hot as it is steaming through the radiator, hissing at me and boiling over when the cap is off and when the cap is on, the antifreeze reservoir boils, hisses and steams like crazy. As hot as it gets, the radiator cooling fan WILL NOT kick on.

I think my problem lies there. My radiator fan is not kicking on which is causing my antifreeze to get HOT at idle speeds (and my temp gauge will go up). This usually happens in traffic or in city driving. Now, when I accelerate on the Interstate, the gauge usually drops.

Now, to answer your question - the engine temp gauge does not increase even with all of this.

I've checked the radiator fan relay and it's good.

Now I am going to replace the ECT sensor and if that doesn't work probably the fan motor.

Maybe it's a combination of a fan that doesn't work and a leaky head gasket. I've been having these problems for over a year. I have a feeling if it was a head gasket, the car likely would have blown up by now don't you?

 

I agree that you likely have a problem with the radiator fan. You can test the fan itself by supplying it with 12V battery power. If it fails to run, then the fan needs to be replaced. If it runs, then either the radiator fan relay or ECT switch is bad. Your engine has three temperature sensors that control the gauge, ECU signals, and the radiator fan. The latter switch is located in the thermostat housing.

You also possibly have a blown head gasket given the boiling/bubbling of the coolant when the temperature gauge is not indicating an overheated engine. Thus, a compression test of the cylinders seems warranted. You might also want to look into the possibility that the radiator cap is faulty and unable to hold proper pressure.

 

How would I directly supply the fan with 12V power to test it?

P.S. Thanks for the reply.