I am having a problem with my 94 integra rs overheating. The main cause for the overheating is coolant loss. I replaced the radiator cap and cannot find any leaking hoses, however, after a day of driving, i lose a significant amount of coolant, which causes a lot of air in the system. In fact, no matter how much i bleed the system (cap off/car running) the air bubbles never cease. I thought at first it could possibly be because i have not had the heater on while bleeding the system, but after switching the heat to on, it doesn't seem to make a difference. infact, the air when the heater is on never gets hot (i did confirm the arm is opening and closing the valve under the intake manifold, not sure if valve is good or not). so im not sure if this gives any hint as to what is wrong. the only thing i can think to do next is possibly a coolant leak test, and a leak down test to see if the headgasket could be the culprit (no obvious oil in coolant/not a significant smell of coolant from the exhaust). i have not performed a coolant flush since i can't keep the coolant in the system. i was just wanting to inquire first to see if i am possibly missing something? any help is greatly appreciated.

 

So, no obvious loss, and no antifreeze smell? You have put in more that the system holds, or are just having trouble getting it full and getting bubbles out? Fill on a steep incline. What about the "water breathing bolt" or part 10, here.

http://www.acuraoemparts.com/delray/...All&vinsrch=no

 

are you squeezing the hoses when u bleed the system with heat on?

 

unfortunately, #10 has been replaced with a regular bolt (purchased motor like this, haven't found one to replace) but i was thinking i could just run it with the cap off to accomplish the same thing, even though i do realize using that bolt would be beneficial. i will try to locate one and replace it to see if i have an easier time getting the air out.

i did squeeze the radiator hoses while bleeding the system, and no matter how long i leave the cap off, there seems to be continual bubbling. like i said, i turn the heat on, but no hot air, and this is with the system at full operating temp.

usually what i have been doing is taking the cap off after a days worth of driving, refill about one quart, start the car and let it reach operating temp with the cap off, let it run a few cycles seeing that the thermostat is opening and closing and making sure the fans are cycling on. while doing this i do lose a little water as i attempt to get all the bubbles out, but the bubbles never stop coming no matter how long i let the car run, and no matter how many times i top it off.

 

Are you really losing fluid? Total input and gestimate the spill with bubbling out. Never filled or you worring about loss? Park on a steep incline, nose up and try filling.

 

yes, losing large volumes of fluid daily. at one point the fluid got low enough to where the car slightly went past the half way point, once it was parked you could hear the fluid gushing into the overflow. i noticed that the radiator cap was missing the center gasketed section, so i replaced it thinking it was a faulty cap. i will try to refill on an incline next time, but do you think that since i haven't been filling on an incline that this could cause this significant amount of air to remain in the system? and for the heater to not blow hot?

we didn't start having this problem until we fixed a leak in the ac system. our heat index is about 115 F, and only started having this problem once it started getting really hot out here.

 

Some engines can get a leak of exhaust into coolant, usually head gasket, and it can be difficult to find. No coolant into oil, and no coolant in exhaust. Friend had this happen and it caused bubbles in the coolant. It did cause coolant loss, but it could be found, it caused overflow as exhaust gas displaced coolant. Your coolant has to go somewhere and should leave a trail. You do not smell coolant under the hood? The reason I asked about total amount coolant is that if you exceed the capacity of the cooling system, then you have to be losing it. If you have bubbles and have not exceeded the capacity, then you just need to fill. Sounds like you are blowing it out, displacing coolant with air/exhaust. There is a test for exhaust, I believe hydrocarbons in the coolant. Some info

http://www.hondacarforum.com/honda-3...sure-test.html

http://autorepairexchange.tribe.net/...e-c897739c7b2e

 

I had a head gasket go like this a few years ago, I was loosing coolant but it wasent in the oil or leaking on the ground. I checked my compression and sure enough one of the cylinders was low. Oh, one other thing I heard about the water can leak into the cabin, but if your losing as much water as you say im sure the heater core isnt leaking like that.

 

What about a leaking radiator? Those plastic end caps are known to leak eventually.

 

yeah its real weird. i went and checked it today and low and behold i see coolant (didn't really lose any). i suppose the radiator cap has resolved some of the issue. so i went ahead and raised the front end and started bleeding again, this time i got lots of bubbles, but it didn't seem as continuous. yesterday, if i started the car, it would only take 1-2 min to get to operating temp, however, while i was bleeding the system today i noticed it took much longer to get up to temp (engine sat below C for several minutes) , but i couldn't get the thermostat to open like i could yesterday, so i'm unsure if i have removed all the air. it doesn't seem like it, because for however long i let it sit with the cap off i will see a few bubbles every now and then. this was with the heater on max (today the heater started working again). so eventually after about 30 min with the radiator cap off, i finally said screw it, capped it and got back in the car and turned the heat off and the ac on. this is where i started hearing a real quick, "dunk" from under the hood. im not sure if it was because i had the car heater on for so long, but when i would hear this noise it seemed as if the car was straining a bit and the ac button light dimmed quite a bit. eventually, with pressing the ac button on and off, the car picked back up and the ac started blowing cold again. the car has never really had these problems, so excuse some of the random details, just trying to describe the problem as accurately as possible.

 

i still need to find a coolant leak tester, but i haven't been able to find one to rent, i tried autozone, still need to see if o'reilys or advanced has one. anyone have any recommendations?

 

The article here

http://www.troubleshooters.com/tlitthypothesis.htm

mentions NAPA about half way down, "How to test for combustion..."

 

thank you very much drive 4 fun, unfortunately, all the napa's in our area have shut down, but at least i know what to look for. thank you for all your helpful suggestions. i haven't had a problem with the car overheating lately, granted its been raining, so the heat has backed off a bit. the new radiator cap does seem to be helping though, thinking now that it must of been the main culprit.

 

I had a radiator cap that came apart and caused overflow. The central portion of the cap came loose and did not come out with the top. It could not go anywhere, and I just lifted it out with a clamp. Replaced, and no more problems. In that case, I had a coolant leak and almost could not find it. Minor overflow at the bottle several times before I saw it. I kept smelling antifreeze when the car was hot. It was a small amount and trapped in the plastic on the underside of the car, and evaporated, on wife's TL. I have learned that if I smell antifreeze, there is a problem even if I do not find it immediately.

Park on a hill and recheck. Often a few last bubbles work there way up. Also, you will see if it has resolved, before it can overheat. Happy it helped.

 

Have you checked out the Thermostat?

 

The thermostat was mentioned as opening and closing. It does not directly cause bubbles. That said, if you actually overheated your engine, you can cook parts. You could get a secondary headgasket leak, or possible finish off and old thermostat. My thermostat failures have been open and over cooling. You should know that soon. Large bubbles can allow hot pockets and overheat areas without necessarily showing full overheat on the guage.

 

today i was on my way home and the car was running nice all day, however, all of a sudden i noticed the temp gauge rised up suddenly. pulled over, popped the hood and saw that the lower radiator hose had come off the thermostat housing. im not sure if it was due to too much pressure (didn't really hear a pop), or if the hose just wasn't properly clamped down (doubt the latter, since i haven't touched the hose the entire time and its been good up till today). anyways, i got it back home and removed the thermostat from the housing. i found that the thermostat was slightly stuck open (possibly not opening fully when reaching operating temp?), so i went ahead and replaced it. i must have sat with the rad cap off, car running with the heater on for almost 45 minutes, and no matter how long i waited the new thermostat doesn't seem to want to open, but at the same time the car wont overheat or get above operating temp., it just sits there, no fans, no thermostat opening. the car blows nice and hot again so i think ive got most of the air out of the heater core, but i know i haven't removed it all from the lower rad hose. im kinda stuck again.

 

Nose up, fill, drive, recheck, and repeat in a couple days. Driving with the inherent load will open the thermostat.

 

ok, well i ended up replacing the radiator and doing a complete flush by removing the front bolt off the block (lots of debris came out with it) and so far the car hasn't overheated once. so i guess my main culprit was the radiator. but now i've noticed another problem, im having ac problems again, but i think ill make a new thread since it doesn't have much to do with the car overheating now. thanks everyone for all of your help.