Rep Power: 0

I decided to join the Civic nation in 2004, with a 4 door Si. I love this product too. Until today, not a single issue with the car. So, I joined to see how others are fairing, as well as seek advice on what I think is a small problem..technically. Maybe, I'll just ask it here, instead of starting another threat. My silver baby was giving off good heat from the vents (it's been cool enough these days to turn it on) and then suddenly, when I stopped at a red light, the hot air tiurned cool and heated up again as I started driving. Did this over and over. Checked to make sure she's full of coolant..no problem there. Do I have a thermostat issue and is that an easy DIY job on this model. Good to bee here. Looks like there really is a nation on here.

 
Rep Power: 811

more than likely the thermostat is stuck open. this can cause the engine to take forever to warm up on a cold day. normally it should close and only circulate coolant thru the engine and heater core and NOT the radiator to warm up the coolant faster. its pretty easy to change. just drain 1/4 of the coolant into a container from the bottom of the radiator by turning the lil valve. close it, then take apart the thermostat housing. be sure to only use a honda oem thermostat and gasket. replace it exactly how you pulled out the old one. i think it only fits one way but who knows. spring side faces the engine. bolt it up, fill back the coolant, leave rad cap off, start car and warm it up, turn heater on, and squeeze the two hoses til most of the air comes out. fill up the radiator as it goes down. once the bubbles stop coming, replace cap and youre done.

 
Rep Power: 0

Thanks for your reply Gearbox. It will help me when I eventually do this job..BUT! It seems my declaration that the coolant was good was a mistake. I made it on the basis that their was lot's of that cool green stuff in the overflow jug. I went back out to the car (this stuff can drive you nuts) and checked the coolant in the rad, once the engine had an hour to cool off. I didn't see any fluid in the top part, so I poured some fresh Prestone in their and was surprised that it took a litre or more. Closed the cap and drove her around and PRESTONE problem solved. The hot air wasactually scorching hot and it did cool down at a stop light to just really hot, but I think that I may have been using up the coolant slowly, so I didn't notice the drop in overall temperature until it hit critical mass today. Clearly, somehow over the last 6 years (since new), I have lost some fluid, so that's got me wondering. Couldn't find a drop anywhere, so it must either be leaking slow, or my recent 1400km trip from Thunder Bay put enough pressure on the hoses or leak that it accelerated the leak..or somehow this stuff now evaporates, when I've never known it to before. Any thoughts on that? Again, thanks for the reply. Great to see Civic Nation taking care of itself.

 
Rep Power: 312

You my friend, have a blown head gasket. Exhaust gases are pushing to coolant out the easiest exit which is the overflow. Our civics also don't use prestone so get that crap out of there when you change the head gasket and make sure you use Honda OEM coolant which is blue. Also, you can't just add coolant, you have to properly bleed the system. Go to a mechanic and get the head gasket checked out but im 99% sure thats whats wrong

 
Rep Power: 811

yeah if it doesnt leak coolant on the ground, its the head gasket.

 
Rep Power: 0

I've blown a head gasket on an Isuzu Trooper before, and if I remember correctly, you could actually smell to cooking coolant inside the car, not to mention a fog or mist coming out the tailpipe, as the coolant accessed the cylinder head and got blown out with the exhaust fumes. Would that be a fair staement? And we use a blue coolant from Honda? What's the difference between the OEM and Prestone, other than the colour? Hmm, head gasket Man, I hope not. Is thgis an issue with 04 Civics, or am just the lucky one?

 
Rep Power: 0

By the way..no white soke out the tail, no smell of coolant anywhere, starts up fine 1st time every time and drives well. If it wasn't for the heat coming from the vents getting cooler at a red light, I would never know there was an issue. The girlfriend did run over a blown truck tire a couple years back and a close inspection underneath did show the lower rad brace and rad bent..bo no leaks. Could this be a small drip from there, now that a few years and some road salt and natural corrosion has set in? I guess I better crawl under there.

 
Rep Power: 811

can still have a small coolant leak in the cylinder and its very hard to tell other than white deposits on the plug and losing coolant without leaking. sometimes on a cold start the engine can misfire for upto a minute til the coolant burns off and it seals the leak when hot.

 
Rep Power: 0

A leak that small, can it be detected any other way? I have zero symptoms, like all the ones mentioned.

 
Rep Power: 312

You do have symptoms. A leak will generally not cause you to push coolant out of the overflow, it will cause the overflow to drain out of the leak. You have a blown head gasket. My car ran like a top with all the same symptoms you have and don't have, and it was a head gasket in its early stages of destruction.

 
Rep Power: 0

Ok, got it. Now decision time. New head gasket and check heads for truenesss or sell while it's still new looking and running great. Funny, cause I popped in on the dealer who sold it to me last week to check out the remaining 2010's (.9 financing deals going on now) and he asked if I wanted to trade her in. Might be time for the 197hp Si.

 
Rep Power: 811

it will just get worse. you can try a coolant pressure test and also a cylinder leakdown to see if there is a small leak. if its very small, it may be hard to detect until it becomes more serious. if you do replace the gasket and have the head checked out, it will prolly last you a long time.just have to measure the costs. obviously $1k for a head job is cheaper than a new car but its up to you. those new civics have their own issues you will find out about too...

 
Rep Power: 312

I'd honestly fix it and keep driving it. If you change the timing belt and everything along the way most of your engine maintenance will be done in 1 shot and you can just drive it for a long time.