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Overheating Honda Civic 1998

as you took parts off, did you notice any corrosion and gunk inside?

asking since you might have a lot of it left in engine itself

did you follow coolant fill procedure?
does it require to get air pockets any special way like taking some plug unscrewed on the engine block until coolant starts flowing out?

ah… if you have an electric fan, are you sure it is getting turned on ? :slight_smile:

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If it is the electric fan failing to come on it would overheat in traffic or idle, not at highway speeds unless you were stop and go on the freeway. Cracked head or block, bad waterpump . Are you sure you are getting all the air out of the radiator?

The recommendation here for overheating seems to be to run a few tests first before replacing stuff. Drive belt tension. Coolant density. Cooling system pressure test. Radiator cap pressure test. Chemical test for exhaust gasses in coolant. Measure flow rate of water pump. Water-bath test of thermostat opening & closing dimensions. Have you done any of that yet?

Your car probably uses a bypass thermostat, so removing it completely is guaranteed to make it overheat. Put a known good thermostat back in.

If you just want to replace another part, the water pump is probably next. The impellers can just sort of wear away with time and miles, so it spins ok but pushes little water.

I don’t think it is illegal to shoot your own car. As long as it isn’t a threat to anybody, just the car. Didn’t Richard Pryor shoot his wife’s car year ago? I don’t think he got arrested for that.

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You’re doing what I call “shotgun maintenance”. That’s throwing parts at the problem hoping something will fix it. The odds are that you’ll actually do a lot of additional damage rather than fixing the car. You’ve already one thing that never should have been done without diagnosis (shaving the head) and another that never should have been done at all (removing the thermostat).

My recommendation is to get the car to a reputable and competent independent mechanic for diagnostic tests. There are a number of things that can be tested that can cause chronic overheating, including but not limited to exhaust restriction, induction system leak (causing lean operation), a bad oxygen sensor causing lean operation, low fuel system pressure, the radiator cap, the (already mentioned) cooling fan, and a few others. You need to get this to someone who understands how everything works and what things cause overheating.

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Thank you everyone. The problem is I am a computer guy, and we think we can fix anything by replacing it. I will put the thermostat back in tomorrow, a brand new one I picked up.
There was corrosion, but I tried to clean it as best I could of what I saw.
The coolant was a 50/50 blend, advertised as ready to use.
A new cap came with the new radiator.
The fan is on, again tampering, I have it running all the time when I first had this problem.
The head was inspected and not cracked, the block I did not see any from my perspective, however the plugs where changed with the new head gasket, and do not show any issue.
*Does that mean, no water there so maybe not a cracked block?
I did not do a procedure to bleed the air, I will do that tomorrow.
*Who do I go to for checking Chemical test for exhaust gasses in coolant?
Have a brand new thermostat, will put it in tomorrow.
I am not as famous as Richard Pryor, he can get away with things so maybe I won’t shoot it.
Tomorrow, I will try the couple of things I can, and then get it to someone if necessary. I have been getting remote control advice over the phone, all this was not my fault. But having a wrench nearby, and ready to take a computer apart anytime, I am dangerous at times, again thanks for all the help.

When refilling the cooling system, the heater control needs to be on Hot. That opens the valve on the firewall that lets coolant flow into and out of the heater core At least that’s how my 1999 Honda Civic works.

If it’s overheated since you replaced the head gasket, you might have warped the head again.

I will try that today - Thanks

When it got to 3/4 hot, I pulled over to let it cool down, so hopefully it would not warp the head. But the plugs are not showing any problem.

I’m afraid that does’t rule out a warped head. I too drive a 1998 Civic, and I recently had a similar issue. I noticed my temperature gauge was running a tad higher than usual at stops, but nowhere near the red. I took it to shop after shop to have the cooling system diagnosed (and nobody could find anything wrong), but in the end, I had to bite the bullet and have a new head gasket installed. It turns out the head gasket was bad (deteriorated) and that was the cause of the slight overheating at stops. When the shop sent the head to have it planed, it was slightly (about 1/32 or 2/32 of an inch) warped.

The problem you’re likely facing is that when the head gasket fails in a 6th generation Honda Civic, it doesn’t exhibit the symptoms most mechanics expect from a failed head gasket, and your head gasket might have been either damaged during installation or improperly installed. If you’re able to rule everything else out, and it keeps overheating, it might be time to let this car go or fork out $900 to have a head gasket professionally installed.

Another problem you’re likely facing is that this vehicle is highly susceptible to damage from overheating. My temperature gauge needle got nowhere near the red on the gauge, and yet the head got warped. I just happened to notice the temperature gauge needle, which normally points at the squiggly lines on the gauge, was pointing to the top of the top of the temperature gauge icon.

The head gasket was replaced last Saturday, not by me even though I have replaced two before, but by my son’s friend who is a mechanic professionally. I took the head to a auto machine shop to work on it. So at this moment I don’t think it is the head gasket. Other than putting in a new thermostat today, and “burping” the cooling system, I would think my next step is to check the water pump.

Agreed. Unless you change the water pump when you replace the timing belt, the water pump is the likely candidate at this time. However, if you reinstall the thermostat, the water pump passes inspection, and it still overheats, I suggest you reconsider the head gasket as a possible cause, in spite of the vehicle’s repair history. Don’t let confirmation bias influence you to dismiss a possible cause. That’s the trap I fell into when mechanics repeatedly told me I would see different symptoms if the head gasket was the issue.

I encourage you to check out this thread: Overheating 1998 Honda Civic

In particular, @UncleTurbo :

Well I just tried to find the air bleed bolt for the cooling system and could not find any special bolt to do it, but found this from another web site: There is no air bleed bolt on models after 1996. Run the engine with the radiator cap off to get the air out. Can anyone confirm?

Sounds right, making certain that you have the key ON and the cabin heat ON as already mentioned to allow the heater core to purge. Having the key ON (engine not operating) will allow the valve that opens the passageway to the heater core open.

Air in coolant will always flow upwards to the highest point it can reach. Parking the vehicle with the radiator fill hole at the highest point (car aiming uphill) will assist this process. I recommend against artificially elevating the front end with ramps or jack stands, because this can inadvertently cause a spot in the system to become slightly higher than its surrounding areas and allow an air bubble to settle there, restricting air’s flow to the radiator fill hole. In this case “settle” is used to describe the entrapment of an air bubble in the passage.

Your task is to allow free flow upwards throughout the system to the radiator fill hole. Since the system is designed to not restrict free flow unless an artificial restriction is added, you have the advantage. :relieved:

NOTE: while proper purging is crucial to proper cooling system operation, you also need to understand that it cannot correct or compensate for system problems. I still highly recommend a good look-see by a competent technician. Continuing to operate the car without a proper diagnosis and fix can only cause the problem to grow.

Mountainbike says it well.

Be sure to catch any overflow of coolant and dispose of properly. It is poisonous to any animal that might lap it up.

After you see the coolant is hot and the rad is no longer burping and is staying filled, cap it then fill the coolant overflow tank to its midrange.

Next morning, when engine is cold, open the rad cap. The rad should be still filled to the brim. If it needs a little topping up, do so, then check again in the days to come.

Best of luck!

If the vehicle has an automatic transmission, pull the transmission dip stick out and check the condition of the transmission fluid.

If the transmission fluid is black, it indicates that the transmission is running hot.

The transmission has cooler lines that go to the radiator.

So if the transmission is running hot, it can cause the engine to overheat.


An excellent suggestion. If your Civic has an automatic tranny, the radiator you replaced might have been allowing the coolant and the tranny fluid to mix. While replacing the radiator should eliminate that problem, you may also want to flush and refill the tranny once you get the engine cooling system fixed. In '98 Civics with automatic trannys, both the engine coolant AND the tranny fluid (which is used as a coolant for the tranny) run through separate sections of the radiator… and these can form leaks between the sections. These leaks will allow mixing, and adversely affect the engine coolant’s abilities and absolutely destroy the tranny.

Hopefully it’s just the air remaining in the cooling system that’s causing the current overheating. The way I air bleed my Corolla, I drive the front wheels up on ramps so the top of the radiator is the top point in the cooling system, remove the radiator cap, turn the heater control to max heat, and idle the engine until water starts to pour into the top of the radiator. I can peak through the radiator cap hole and see when the water starts coming in form the top hose. Takes 5-15 minutes. Sometimes I completely remove the top radiator hose from the radiator & direct it to a bucket, so when the water starts pouring out I can judge how fast, as that gives me a way to judge the thermostat and water pump function. When you do all this don’t walk away, keep an eye on the radiator fill level at all times, and be ready to pour more coolant mix in, as the level can drop really fast.

Most auto parts stores stock this as a diy’er test kit.

Note: I get the sense you are assuming this problem isn’t due to a faulty water pump. Before going too far down other paths, suggest you test that assumption. Faulty water pumps – usually it is worn off impellers – causing overheating is a pretty common thing reported here. Best of luck.