Mhillips

So I have a 1999 Honda Civic Lx and am having a horrible time fixing an overheating problem. I overheat when I'm idling, especially when I have my AC on. When I turn my heater on the car cools down almost instantly and when I'm driving the car doesn't get hot. I used to have a leak but after replacing a bunch of parts I dont appear to anymore. I pressure tested myself earlier and it looked good to me. So far I have replaced the radiator, the cap, all of my heater hoses, bypass hose, all hose clamps, water pump and gasket, timing belt, and the thermostat. I'm 99% its not my head gasket because my exhaust, oil, and coolant all look good and I tried a test with my radiator cap off , another test to see if fluid flew out of my cylinders, and I used an engine block test. My AC and radiators' fans relays and fuses look good and my radiator kicks on after a while (like 15 minutes or so). Any ideas? I have no idea what else to do. Thank you.

tempsohc

dang you pretty much changed everything dealing with the coolant, any check engine lights on? only thing I can possibly think of is the cars running lean thus running hot, but when your moving you got that extra airflow so it keeps the motor cool? again just a theory

Cjlarson14

Just a question here, but did you empty your entire cooling system while replacing parts and did you bleed the system after replacing all those parts?

Mhillips

Well, I changed a ton of stuff, but I'm wondering if maybe it could be the coolant sensor? Maybe it could be a head gasket too. My 2nd cylinder looked a little dirtier than the others when I pulled the spark plugs and the 2nd cylinder plug was also dirtier. They were not white though, they almost looked like rust. I am not getting check engine lights, however like 2 months ago I had a check engine light for my cylinder. After adjusting the plugs to the correct torque (PO should stay away from working on cars) and reseting the code I havnt gotten it again.

I'm think maybe that too; I know my rad fan comes on after like 15 minutes or so, I dont know if thats a normal time or not, but I feel like sometimes when I'm stopped it doesnt come on all the time.


I did when I replaced the radiator and when I replaced my hoses. I undid the rad plug and filled it up with water, ran it until it was hot, drained it, and did that a couple of times. Between this system of flushing my system I would run it with the heater on and massage the hoses until the bubbles stopped. When I replaced my water pump, I just filled the car up with coolant, put my heater on, tried to bleed it, closed it up and called it a day.

Cjlarson14

Did you release the coolant in the water jackets? Bleeding the cooling system usually involves some time. When you refer to "tried to bleed it," does that mean you bled it properly??? or tried to bleed it and couldn't figure it out? Also have you checked your timing? Your stating your plugs in cylinder 2 look a bit harsher than the rest. Timing being off could also cause overheating issues, although unlikely. Still, I'd check it to be sure.

Mhillips

I had a friend whos a pro mechanic who did the timing belt and water pump for me, but left me to do all the bleeding and filling of the coolant. He said he had the timing set right. I'm not sure if I got coolant in the water jackets, how would one go about testing this? How long does bleeding normally take, like for it to all cycle through the engine? Maybe I havnt been doing it right.

tempsohc

the way ive bled my system with no problems in the past is top off with the car off, start the car, keep toping off coolant until bubble stop coming out. Usually is done a little te while after the thermostat opens.if the air bubbles don't stop then it could possibly be a blown headgasket or another leak in the system. Do the upper and lower hose get warm?

strategy400

I suspect the fan may be intermittent, especially if the heater cools it down.

EJ8mike

^^ yea, me thinks fan not coming on when it should, only sometimes

Former User

When the engine is overheated, is the lower radiator hose hot, warm, or cool?

Mhillips

I opened the hood, took the rad cap off, turned on my heater, and let the car run. I had bubbles coming out for almost two hours but finally the bubbles stopped. For a minute I thought I had a blown head but I think I had a ton of air in it. I'm gonna see if that fixed anything.

I was thinking the fan might be intermit too. Would the coolant temperature sensor cause the fan to not turn on as frequently as it should? I know the fan will spin, I just dont know if its spinning fast enough or all the time when it should. I'm like 99% sure the fan fuse and relay is good. I swapped the fuse and relay with that of the condenser fan and my condenser fan ran the same, leaving me to believe both fuses and relays are good.

The lower hose feels warmish hot, like the upper hose is super hot and the lower is still hot, but not nearly as hot as the upper hose.

Former User

2 hours to bleed all bubbles? I'd be a little worried about a blown head gasket too.

If the engine continues to overheat after the long bleed, also check whether the new thermostat is installed correctly or is stuck closed.

Mhillips

I just took it for a test drive and it started to overheat after about 3 miles. I noticed when I have my fans running inside the car gets hot, my ac button doesn't actually have to be activated. When I turn the fans off the car doesn't really cool down but it stops getting hotter. With the AC on, the temperature gauge goes all the way up and when the fans are on it goes about 3/4 of the way. When I turn the heater down it cools it down for the most part but not all the way. I also popped the hood and checked my radiator fan and it was spinning but the system was still hot.
After I turned the car off it sounded like there was bubbling, possibly from my overflow tank, but I didn't check because the good was down.

I pulled my thermostat out when I had the water pump replaced to make sure it wasn't it and I boiled it over my stove in water and it opened so I'm assuming its good. I put it in the same way the PO had it in, unless the PO put it in wrong. It seemed to me I couldn't even get it in upside down because of the gasket. Maybe not though?

Former User

Here^ Was the lower radiator hose, cool, warm, or hot?

Mhillips

I just checked the hose now, the cars been off for about an hour. The upper hose is still really really hot and the bottom hose is hot, but not as hot. I'd say the bottom hose is more hot than it is warm. I checked the overflow tank and it was bone dry and I checked the radiator. There really wasn't a lot of pressure if any when I took the cap off, but the cap looks fine and I bought it like 2 weeks ago. The radiator was a hair short on coolant, so I topped it off.

Former User

At this point, it seems that either the head gasket is blown or the water pump is not working. With the radiator cap off and the hot engine idling, do you see coolant movement in the radiator.

Mhillips

Yes, when I pull the cap off and fire it up it will start to have some movement after a little bit.

Mhillips

Sorry for the bump but i figured there was no reason to make a new thread. So I bit the bullet today and had my head gasket replaced. The head and block didn't look warped and the gasket looked find but I had it changed anyways and the turd is still overheating. I'm about ready to take the civic out back and shoot it. Any ideas? I was looking at other parts that may affect my temperature and the only things I havnt replaced are the heater core, coolant sensor, radiator fan switch, and something I found at autozone called the coolant fan control. I'm not sure what the coolant fan control is, but the description says it is an adjustable electrical thermostat for the fans. Has anyone heard about this or have any ideas what's going on? The car is getting hot when I idle after driving around town for like an hour or so. The fans work, but I'm thinking they arnt coming on when they always should or they arnt spinning fast enough. Thank you.

strategy400

When the car gets hot, go out and open the hood and visually see if the radiator fan is on.

Mhillips

Well I had my friend who helped me with the water pump take a look at the civic again and the ignition timing was way off. I guess it's supposed to be at 12 and it was advanced to 56, so we adjusted it and the car start was running fine. Actually, I couldn't get it to overheat. So this morning I took it for a drive and after 20 miles the thing started to overheat after about two minutes of idling. I popped the good and the radiator fan was spinning.

Edit: my car kinda smells funky with the AC on while I'm idling. I just noticed it and can't make out of it's exhaust or antifreeze but it doesn't smell right.

Edit again: so I put in a new thermostat thats rated to open at a little lower temperature and replaced the radiator fan switch and the coolant sensor. The car is still getting hot but I noticed when I'm idling and the temperature goes up, if I step on the throttle and keep the rpm between about 1500 and 2500 the temperature drops almost instantly. I'm not sure what this means and would appreciate any suggestions or advice. Thank you.