I have a 98 DX hatch, automatic that is my daily driver.

For a while, the car was overheating so I started replacing and testing things to find what it is and I've gone through almost every single thing that I possibly could.

I have replaced:

-Thermostat (got it today, old one was only 3 months old)
-Fan Switch
-Fan Relay
-Engine Coolant Temperature Sensor
-Radiator
-Radiator Cap
So as you can see, I have replaced everything but the fan, hoses and wiring.

I suspect it to be something with the thermostat or thermostat housing because, when I popped by hood, I found THIS....

That ballooned hose would indicate that the thermostat is blocking flow and causing pressure build-up, yes?

 

Also, I think it's worth mentioning that it only happens after 30-40 mins of driving around town.

 

Anyone? I don't want to drive it like this and cause any damage

 

you replaced the fan switch and relay, but does the fan kick on?

does the bottom hose get hot? or just the top?

did you properly bleed the cooling system?

look like it may be the WATER PUMP then.

 

The fan comes on for the first 20-30 minutes and everything flows nicely but does not come on when it overheats and balloons my upper radiator hose. (because the fan switch is on the cool side of the thermostat, I think)

I bled it in my driveway at an incline and refilled as needed.

If the water pump was bad, wouldn't it overheat within the first 5-10 minutes rather than waiting?

The bottom hose gets hot but not scalding like the top one does. The bottom one can be held in your hand as long as you like but is still hot.

 

Did you blow a fuse that powers the cooling system?
Are your hoses clogged at all?

Possibly try replacing the top rad hose. If the pressure inside the cooling system is building inside the hose and not the radiator due to a worn out hose then the cap will not open to let coolant out when engine becomes warm

 

My upper hose just blew up on me on my way to work. I think you're onto something here but why is there so much pressure anyway? Shouldn't the thermostat be opening and relieving it?

 

Anyone else have any ideas while I find some new radiator hoses and check my fuses?

Someone suggested that maybe there's a blockage in the block, can that happen? Rust maybe? I was using water in it for about 3 weeks.

 

Test for headgasket leakage.

 

Would this have caused the pressure build up that burst the rad hose?

 

Thermostat does not control pressure or relieve it. The thermostat opens and closes depending on coolant temperature to warm up the coolant or cool it down. Just because the thermostat is closed does not mean pressure is just building up behind it until it opens. The radiator cap controls pressure. For every pound your radiator cap is rated, it increases the boiling point of the coolant or water you have in the system. If it's just water and you have a 16lb radiator then the boiling point of the water in the system is now 260 degrees. 212 for the water and 48 for cap rating. Anything over the cap rating is vented into the coolant reservoir. The ballooned hose blew up most likely because it was old. What rating cap are you using? Having too high of a pressure cap could cause excessive pressure in the system. Have you noticed oil in your coolant/ water? Do you have to constantly add water? Any water in the oil? Any excessive smoke while driving?

 

^^This. It doesn't look like you have an OEM radiator cap. They aren't expensive at all at your Honda dealer.

 

After your car has warmed up, carefully open the radiator cap (with a rag) and look at the water/coolant flow and If it's moving rapidly your water-pump is working. If it's not it could be a bad pump or the thermostat is stuck in the closed position. It's okay to run your engine without a thermostat temporarily, so you may want to try it to rule out a faulty one.

Here's a couple links that may help: http://voices.yahoo.com/8-things-cau...t-7520442.html
http://autos.yahoo.com/maintain/repa...ques014_2.html

 

Sounds like it's time for a new water pump

 

I was using water in it for about 3 weeks.

 

Oh I know that the thermostat doesn't open from pressure but the coolant had to have been boiling as my temp gauge read past half-way which is why I suspect it.

I have no idea on the rating of the cap.

I haven't noticed any oil in the coolant, no. And no coolant in the oil either. Only white smoke while driving is when I floor it and it's not much at all. I think it's from missing cat.

I was having to add more water all the time though. (was water then but coolant now)

 

White smoke=coolant/water=headgasket

 

try running the car with no thermostat to try and rule out the idea that the thermostat is stuck