what does it mean if my upper radiator hose gets hot and the lower doesn't?

this is what i've done so far. changed radiator, thermostat, head gasket, intake manifold gasket, and relay. i know my fan works, it just doesn't cut on cause i'm guessing my coolant is flowing through the whole system or something like that.

***PROBLEM SOLVED***

 

It means that your radiator is working. That's how they should be. The fan shouldn't turn on if the coolant running through the lower hose is cool.

 

even if i let the car run for 10-15min? and water fizzed out of the top and the temp gauge starts to rise. so i just changed the head gasket, hopefully it doesn't do this anymore. i tried running it, and was waiting for the fan to kick on, but nothing, so i cut it off.

 

get a new radiator

 

The lower hose should never be hot, no matter how long you run it. The radiator takes hot liquid from the upper hose, cools it down, then sends it back to the motor via the lower hose. If the lower hose was hot then your radiator wouldn't be cooling the liquid. Where did the water fiz from? If it was from the radiator cap then replace the cap.

 

lower radiator hose not being warm seems to be thermostat problem. fan not kicking on is controlled by fan switch. is your head gasket on upside down?

 

SOMEONE DIDNT AIR BLEED THE SYSTEM!!!!!!......what motor does ur car have and what year engine is it cause some of the older d and b series enignes have a bleed stud....im 99% sure thats ur issue

 

i did get a new radiator. read the post.

well i didn't put the cap on all the way yet, cause that's what it says in the honda manual. for me to put it on loosely and let the fan cycle twice, then add more water if necessary and lastly tighten the cap. plus, the new radiator came with a new cap. maybe i should just wait longer til the fan kicks on, hopefully...

i changed the thermostat. the fan switch is where again? and how can i check if the fan switch is bad? no, i'm pretty sure it's not on backwards. besides, the problem accured even before i changed out my head gasket.

d16y7. it doesn't have a bleeder screw. the 10mm screw with a hole in it where you release air out of the system til coolant shoots up right? looks like the brake bleeding screw, but where the upper radiator hose is? well, the manual tells me to leave the radiator cap on loosely and let the fan cycle twice. but the only problem is, the fan doesn't kick on. now, before i changed out the head gasket, i hooked the fan straight up to the battery and let it run for awhile, but the temp gauge still went up!

 

you said your radiator is fizzing with the radiator cap off?

If so, do a compression and leakdown test. You may not have properly put on the headgasket.

 

yea it was. i'm not even sure if it still does it. cause i changed out my head gasket today and when i turned on the car to let it run, well i assumed it was gonna overheat again cause i didn't know the lower radiator hose was suppose to be cool at the time and the fan didn't kick on, so i shut off the car and left it and that.

buy yea, don't i need a special tool to do a leakdown test? and a compression check?

 

yeah you do need special tools and an air compressor to do a leakdown test.
but there is a good chance you put the head gasket on wrong. do not run your car hot either or you may WARP the head and face bigger problems.

 

w/p leaking? was headgasket blown when u changed oil/coolant mix can cause problems. just somethin to think about.

 

Clean the reservoir so you can see into it well. Fill the radiator and the reservoir completely. Put the radiator cap on and make sure everything is hooked up properly and sealed tight. Turn the cabin heater to maximum and don't use the recirculate button. Open all the windows and and start the car. Let it run for one minute and then shut it off. Check the radiator and reservoir, add fluid if necessary and then tighten the cap. Turn the car back on and repeat until you can't add anymore fluid after 2-3 tries. If the heater is working well at this point, rev the motor a little and see if you are still overheating. If you are overheating just a little, let it run awhile and see if it goes down. If after filling as much as possible the heater doesn't work or if the motor seems too hot, stop the car and let it cool. Check the reservoir regularly throughout the process. If you ever see bubbles coming out of the black tube in the res, stop the car.

 

Did you do a compression test and leakdown prior to changing the headgasket? I would only do a head gasket change after confirming with a compression test and leakdown. Why guess when you can make sure.

Are you overheating while driving? while car is stopped? With radiator cap off, is the water BUBBLING out or fizzing? Did you torque headgasket with the proper torque specs and sequence? Was head checked for warpage prior to putting it back on? Radiator is same size and specs as oem (not the cheap ebay 7/16' radiators)? Thermostat is oem? coolant used to refill is mixed with 50/50 mix coolant?

I also noticed, you did not mention your water pump yet? After all the work of swapping out the head gasket, did you at least swap out water pump too?

http://www.harborfreight.com/cpi/cta...emnumber=92697
http://www.harborfreight.com/cpi/cta...emnumber=94190

I know its harbor freight, but, if you just want to use it once, then, go return it after your done. No questions asked.

 

i agree check the water pump. i've heard of cases where the blades on the water pump will disintegrate and it doesn't leak or anything but doesn't circulate the coolant either. also, your fan switch should be located on the thermostat housing. has a two wire green plug going to it

 

d16y7. it doesn't have a bleeder screw. the 10mm screw with a hole in it where you release air out of the system til coolant shoots up right? looks like the brake bleeding screw, but where the upper radiator hose is? well, the manual tells me to leave the radiator cap on loosely and let the fan cycle twice. but the only problem is, the fan doesn't kick on. now, before i changed out the head gasket, i hooked the fan straight up to the battery and let it run for awhile, but the temp gauge still went up![/QUOTE]


do this bro topped off the fluid put the cap on tight start the car and let it warm for up for like 7 -10 min while its warming up what u do is squezze both rad hoses one after anohter that will speed the coolent through the styem and also work the air up to the rad cap ... after ur 10 min is up take off the cap and watch the air bubbles come out ...do this about 3 or 4 times after the 2nd try then u open the vents when ur done with the 4th try rev the engine with the vents open if ur heat is SUPER HOT u kno all the air is out of the system....i hope this helps u bro

 

okay, i drove it this morning for about 10 mins and temp gauge was where it was suppose to be. got to the house, and checked on the fan, still wouldn't turn. i'm thinkin it may just be the fan switch now???? but thanks, i will try what you suggested just to be safe.

i didn't do a leakdown nor a compression test prior to the change cause while parked, it started to overheat a little and i saw coolant fizzing out of the top of the intake manifold. that would only happen if i had a leak in the head gasket right?

i overheated when my car was parked. with the cap off, i want to say it was bubbling. i followed the torque sequence and specs straight outta the honda manual. i didn't check for warpage which i shoulda did. radiator and thermostat i got for o'reillys. coolant mix is 20/80. (it was bubbling before i changed the head gasket. i haven't seen it bubble since. the only thing now is, the fan doesn't seem to turn on)

i wasn't thinkin at all about the water pump dammit. i guess i'll try the fan switch first and if that don't do it, imma have to change the water pump.

the only way to actually check the pump is to remove right? is there any way i can test the fan switch?

thanks. i'll try this and see if it's any better afterwards.

 

sorry but this is wrong. each hose should be equally hot when at operating temp. if the upper hose is hot and the lower is cold then the thermostat is not opening. this is either caused by bad thermostat or air in the system. your description of bleeding was partially incorrect as well.

OP, start by bleeding system properly
1. make sure engine is cold
2. remove cap and fill radiator with coolant
3. turn heater on and run engine with cap off until car is up to operating temp (radiator fan cycles on/off)
4. continually top off radiator as the coolant level will drop as the thermostat opens
5. replace cap and fill overflow to full mark.

you can jack up the front of the car and pump the hoses with your hands to help work the air out. note that the rad fan doesnt come on until 200* and it may take quite some time (10-15min) especially at idle. also lightly reving the engine will help to get the car up to temp quicker.

 

You would know it was a water pump issue if the temp was fine while driving but then all of a sudden at idle the temp went to hot that meant ur water pump ismost def ****ED!....now this is the proper way to check if ur fan switch is bad follow these steps

1. Remove the ECT switch from the thermostat housing

2. Put the ECT switch in a container of HOT water .....UR BEST BET WHEN DOING THIS IS TO CUT A HOLE IN A PEACE OF CARDBORD AND PUT IT OVER THE THE HOT CUP OF WATER

3.Heat the water, and check the temperature with a thermometer

4.Measure the resistance between the A and B terminals
TESTING IT COLD SHOULD BE AROUND 5 - 15 DEGEES COLD!
THE TEMP OF THE WATER SHOULD BE AROUND 196-203 DEGREES HOT!
IF U HAVE RESISTANCE WITH IT COLD ITS FINE
IFU STILL HAVE RESISTANCE WITH IT HOT UR ECT SENSOR IS ****ED

G/L

 

you can test the fan by jumping the 2-pin connector with a paper clip, you will hear the relay click and the fan will turn on. if that checks out but the fan still isnt coming on to the point you are overheating at idle, then replace the switch.

 

If both hoses are equally hot than the radiator is doing nothing. If the radiator cools the liquid in any way, the lower hose will be cooler than the top hose. Sorry man but simple physics states that you're the one who's wrong. If you still don't understand how removing heat will cause there to be less heat, here is a Wiki on heat transference http://en.wikipedia.org/wiki/Heat_transfer .

 

lol, thanks for trying to be a smart guy with the wiki link.

1. i understand how a radiator works
2. go drive your car for 30 minutes, pull over pop the hood and grab both hoses they will be equally hot
3. you need to realize that our cooling system is meant to keep the temp in a specific range (176* is opertaing temp). the thermostat opens and closes to control coolant flow to make sure the car stays in this range. so the coolant does not get cooled that dramatically when coming out of the radiator

so stop trying to talk down to me, my post stated facts, was not rude toward you in any way, and is correct. you are wrong in stating that your lower rad hose should not be cold at all times

 

1.Then you know that it makes the liquid cooler
2.There's no need to keep making stuff up bro. We've already established that if the radiator cools the liquid at all then it will be cooler, even if you can't tell the difference by touch. Do you really think that when the liquid is cooled by the radiator it stays the same temperature?
3.The engine is kept at operating temperature because the radiator removes the heat generated above a certain point. If it didn't make the liquid cooler, the engine would get hotter and hotter until it blew. We're not discussing whether the radiator always cools "dramaticly," we're talking about how when you say, "each hose should be EQUALLY hot when at operating temp," you're full of s**t.

 

this is a false statement, that was the point of my post. it wasnt meant to start a physics lesson. i will agree that both hoses may not be EXACTLY equal in temp but the difference will not be noticeable by touch and both hoses will be hot. (how much do you think the radiator is cooling when the car is not moving and fan is not on? with no airflow there is very little to no "heat tranference")

if the top hose is hot and the bottom is cold then the thermostat is not open. if this is happening AND the car is overheating then there is a problem. either 1. thermostat has failed in the closed position, 2. air in the system, 3. the system is low on coolant. the OP needs to make sure the system is bleed and thermostat is opening properly before moving forward.

 

thanks for your help. if the fan won't turn on by itself, what could the possible cause? it was working before i did the tuck. i know the wires are all good. possible sensor maybe?