Rep Power: 0

Ive replaced t-stat (even checked it on the stove to see if it was working) flushed the whole system, new coolant, new water pump, new radiator cap, new thermo-switch and fan works.

And the car still almost overheats in town and on the highway. It will get just below the Red H and stay there, probably because the fan keeps it from going just a little further.

What am i missing? why cant I get the temp down.


and it will do the same thing with A/C on or off.

 
Rep Power: 512

may be headgasket then..

 
Rep Power: 0

What would be my symptoms of the head gasket? Im not loosing coolant and its not blowing out.

 
Rep Power: 512

When's the last time you checked/changed your oil?

 
Rep Power: 0

checked the oil about a week ago, normal level. and this has been going on for months

 
Rep Power: 512

didn't look frothy at all? I only said headgasket because you checked/did everything I would have done before finally thinking "gah damn.. blown headgasket... maybe.."

 
Rep Power: 0

Im thinking the way you are..but nothing says headgasket. Ive flushed the system numerous time but could i have some air pockets still?

Ive spent a lot of time trying to vent the system but maybe i need to do a little more?

 
Rep Power: 512

I'd say get a compression test just to be safe.. I just got quoted at a Pep Boys for just shy of $100 for a "drivability" test, compression test was included in that.

 
Rep Power: 208

Take the radiator cap off and run it and see if air bubbles come out.

Compression test it for low compression.

Look in oil for toothpaste like substance.

Look at the spark plugs for a little bit of white substance on a fouled plug.

If any of these things are present then you probably have a bad head gasket.

 
Rep Power: 375

Pull off the cap again and look for corrosion inside your radiator.
Im guessing a blockage, try taking the radiator out and pouring water though the top and seeing how fast it travels through out the bottom.

You could also check the headgasket by pressure testing the radiator, head over to harbor freight tools and buy a cheap set. Wait till your engine is cool add coolant to the top of the filler neck attach your pressure tester apply 13.5-18psi and watch for a drop in pressure.

 
Rep Power: 0

Thanks all...I actually just flushed the system about 2 months ago. Filled the radiator up and then opened the drain to see how fast it drained. Dont know what i good time limit is but it drained pretty fast. So i donmt think a blockage.

Im going to change the oil soon (its time) so ill look at the oil even more.

Id all that looks good then i think i might have had air trapped in the system.

Some cars ive seen have a vent from the upper radiator hose area, but mine doesnt. I used to vent it by running with the rad. cap off but maybe it wasnt doing enough? anyone recommend a better way?

Ill probably run a compression test to see what i find.

 
Rep Power: 208

Bleed the cooling system.

To do this fill up the radiator to the top and leave the cap off. Start the car with the heater on and let it warm up all the way until the thermostat opens (normal operating temperature). Keep filling up the radiator as the air comes out(basically keep it full the entire time). When air stops coming out (kinda bubbling), top it off one last time and put the cap back on and fill the resivior.

 
Rep Power: 0

To add to that
-Jack the front of your car up, put it on ramps, or park it on a slanted driveway to allow for the air bubbles to come to the top quicker.
-Turning the heat on as high as it goes also speeds up the process.
-If after about half an hour or so you are still seeing bubbles rising just as frequently, inspect them to see if they look kind of soapy. These could be exhaust getting into your coolant, which would once again, point to you headgasket.

 
Rep Power: 208

^ Smart. I never heard of jacking it up!

 
Rep Power: 0

well vented the crap out of the system and it still heats up!

Its got to be the head gasket. Should i just do a compression test to see if theres a out of whack cylinder?

 
Rep Power: 0

i would just to do it...

 
Rep Power: 208

Yes. Do a compression test.

 
Rep Power: 0

ok did the compression test....180-185 psi on all 4

 
Rep Power: 208

Hmm maybe the radiator. It doesn't sound like a headgasket to me, but I have been wrong before. If the oil looks good and the coolant looks good and compression test is good.

 
Rep Power: 0

Ya im clueless now...ive checked everything i could think of!

 
Rep Power: 313

Well, overheating could be lots of stuff, really. You said your coolant level is okay. What is your overflow level at? Is it possible that your water pump has failed and is no longer circulating the coolant? You could have a plug in your cooling system in places such as the rad or the heater core. I mean, if your overheating there are LOTS of things you can look at. It takes a while to diagnose but it's important to do so. Don't drive the car under those conditions or you WILL have a head gasket issue.

 
Rep Power: 0

its just weird cause i can sit in traffic all day and no problem....only when im on the highway with a lot of airflow over the radiator it heats up? its weird..


o and speaking of heater core, wheni was was venting it i had the heat on but it never got hot?

 
Rep Power: 812

first thing to do is the thermostat. make sure its a honda oem piece, otherwise you will have serious problems. next replace the radiator cap, again honda only. bleed the air out. then make sure the fans are coming on when the engine gets too hot, and at least when you turn the ac on. after that we can talk about other things. those are the most common.

i had the exact same problem i just fixed. car was overheating on the highway, fine in traffic. thermostat wasnt opening to allow coolant to move thru the radiator. so it was basically in closed loop mode recirculating thru the engine. basically like not having a radiator. i bet thermostat fixes it. i know you said you replaced the tstat, but was it with honda oem? aftermarkets do not open as much as they need to, and you have much less coolant flow. its supposed to open almost 1/2 inch in boiling water.

 
Rep Power: 313

How is your overflow? Is it full past the MAX line? That's a very important question. It takes a really long time for a car to heat up under idle. Especially when your adding room temperature coolant to it. A car won't blow hot air unless its warmed up. If your car is fully warm and is still blowing cold air when you stop. You have an air bubble in your coolant system somewhere. To 100% eliminate head gasket, you have to check for exhaust in your coolant system. Call around and find a shop that can do this test.

 
Rep Power: 0

i got a factory replacement t-stat and even tested it on the stove, opened at least a half inch. new radiator cap as well.

the fan works perfect. when the temp gets up it turns on and cools it down (in traffic) but on the highway it will get up to the temp of the fan coming on but never go down until slow down.

as for the heat, the car is warmed up and still wont blow heat out the vents.

 
Rep Power: 313

You have air pockets in your cooling system as I stated previously. That being said, is your overflow full past the MAX line?

 
Rep Power: 812

try bleeding the air. park on a steep incline or jack the front up, open the rad cap, warm up the car to operating temp (it may be faster to drive the car first to warm it up, then open the cap hot with a bunch of papertowls around to catch the coolant). with the cap open and the car running and warm, squeeze and tap on the hoses to make the air come out. also be sure heater is on max during this process. see if you notice any air bubbles coming out the radiator neck. if so, keep going for 15 mins or more til most of the bubbles are gone. put cap back on and youre done. if no bubbles are coming, it may be clogged heater core in the dash. that would also explain no heat in the cabin. do you mean there is no fan blowing? or the fan blows but its just cold air? is your ECT (engine coolant temp) sensor good?

 
Rep Power: 812

also when you warm up the car and feel the upper and lower hoses while the car is running, are both hoses hot? what about after you turn the car off and feel them again maybe 10-20 seconds later? what should happen is with the car warmed up and running, upper hose should be hot, lower hose should be warm. when you shut the car off, both hoses should be hot. if the lower hose is cool, theres a problem either with the thermostat or a clogged radiator. does the car smell "hot" when it overheats differently than usual? if radiator is partially clogged, it could be slowing down the coolant flow too much. if completely clogged, you have no cooling ability.

 
Rep Power: 0

yes the overflow is full. sorry thought i said that

the upper and lower radiator hoses are both hot after getting the car warmed up. The lower one stays cool until it gets up to temp then the t-stat opens and both hot.
I check the hoses after shutting it down next time.

The fan is on when i have the heat on but no heat comes out the vents, just outside air temp. Guess the core is clogged? best way to clean it?

Which one is the ECT? I changed out the thermo switch already on the t-stat housing for the fan, it was bad and the fan wasnt coming on, but now it does

 
Rep Power: 313

Well, if your overflow is full right to the top (past the max line), you have a head gasket issue. If it's only full to the max line your okay.