jwest1150

Hi all

I have a stock 1999 Civic EX with D16y8 motor. As of late, the car has started to have fluctuating heat temperatures; it shows its going to overheat, and the temperature falls. Usually, after around an hour of driving (however, as of late, it takes around 10 minutes of driving) the car's temperature gauge will begin to rise as a steady pace. This only happens when the car is idle and not moving (IE a stoplight).
Once I start driving like normal, the temperature begins to fall to the normal operating temperature. I decided to let the car run outside and see just how high the temperature gauge will go before stopping, which will stop right above the middle logo. Around this time, I do hear the radiator fan kicking in.

Any ideas what this is? i remember reading it might be a bad thermostat, but I wasn't too sure how to search the forums for this. Any and all advice would greatly be appreciated!

Thanks.

virgineg6

Start by bleeding the system correctly

joeshmo

I had a similar problem with an older car, the car would overheat at stoplights but did fine, especially on the highway. turned out my radiator fan wasn't blowing air strongly enough. I was told to put my hand about a foot from the firewall and see if I could feel the rad fan and sure enough, I couldn't.

jwest1150

I should try this tomorrow. i would need to replace just the fan then correct?

virgineg6

Not necessarily it might not be receiving 12 volts and thats why its weak (if it is weak i mean)

jwest1150

Sounds good, it could also be bubbles in the lines? Which is why i should bleed the system?

Thermostat is pretty much out of the picture then correct?

HondaPartsHero

Did you check your coolant level? The system normally shouldn't have air introduced into it unless there is an issue. If you haven't checked that would be the first place. You may have a small leak, radiator perhaps?

fallrivercolin

Your water pump could be weak as well, and not moving the water fast enough at 800rpm

motegicivic

I have the same problem with my 96 ex.

I have bleed the system, still happens randomly like every 2 months only at idle.

I have a new radiator.


This is what I found, the fan seemed to come on late, gauge will go 3/4 up at idle then come down as I drive.

When it happens I check the coolant level, when you look in the neck of the radiator, seems ok, but it is not, I have to add coolant like 16 ounces maybe a little more, I used a plastic cup that was like 9 ounces and needed to do it more than 2 times, seems after I add the coolant it is fine.

I might have a slight leak, but no coolant on the ground, so I will just coolant every few months.

jwest1150

Little odd. I checked the coolant level about a month ago, and all was well. The problem has been persisting a bit more as of late, so I checked the coolant one more time. It was completely dry. I filled the coolant reseveoir to the top, and drove her for a bit. The gauge still crept up. i have no coolant leaks, just a small oil leak which im in the process of fixing.

Double checked the radiator fan, and it not only kicks in but is doing its job perfectly. Checked hoses and haven't seen any noticable leaks. The temperature went up again as someone above said to about 3/4s, and goes back down upon driving.

Not sure what to make of this? I could check the water pump. Whats a good method for diagnosing this?

Thanks for the replies....

jwest1150

Also, I notice the temperature gauge stops at the same spot all the time, which is a bit before the H. I left the car running for about 5 minutes AC on full blast just to see where it would go up to, and each time it stops in the same exact spot...

motegicivic

You said dry, the radiator or overfill tank?

jwest1150

the overfill tank as in the coolant tank correct? if so, then yes it was completely dry. I am going to add coolant to the radiator once the car cools down.

motegicivic

How was the level in the radiator itself? The overfill tank should not be dry, I am wondering if you are losing coolant somewhere, doesn't mean you will see it under the car.

Do this, start the car cold take off of the radiator cap and see if there are bubble, also check the overfill tank see if there are bubbles there.

jwest1150

Ok, so i filled the resevoir to the top, and let the car cool off. Went to check it, and the resevoir was empty again, so filled it up, and checked the radiator with the on. No bubbles, so added some and managed to get some bubbles...took awhile though. It was super low.

I am wondering then where I can be leaking. Unless I was a blind bat the last time I checked the coolant levels. The car is running good now, did a neighborhood 5 mile drive to and so far so good....

Still doesn't account for the sudden loss of the coolant. any areas to check?

motegicivic

are you checking the neck of the radiator itself for the proper coolant level, not just the over fill tank?

jwest1150

yes. All is well now, filled it to the proper level.

99civ

I had to replace my radiator this week because my coolant was low and reservoir was dry. At first I thought it was my cap because there was coolant all along the top in the foam piece by the front of the of the car(length of radiator about a 1/4 of an inch in width). The plastic caps on top of the radiator have issues cracking over time from what Ron had said in my original thread.. It doesn't leak onto the ground at all and all of it gets absorbed into the foam/a little on top of the fan. I got a new radiator at radiatorbarn.com for 55 shipped and it was here in 2 days. Vegas to Ohio(fast shipping).

EDIT: However, my car never over heat but I caught it early enough and I barely drive my DD far enough to ever get to full hot temperature anyway. I drive it maybe 5 mins to work or 5 mins to the gym and that's it.